Fossils

["Group: AMMONITIDA Subgroup: PACHYDISCIDAE Invertebrates | 151 Pachydiscus Informal name: Ammonite The family Pachydiscidae includes the giants limestone-infilled of the ammonite group, and specimens up living chamber to 2m (6\u00bdft) in diameter have been found in Late Cretaceous rocks. The involute shell shell is moderately involute and form compressed, and carries short, gently curved ribs. The venter rounded is rounded. venter HABITAT A competent Typical diameter 6cm (21\/2 in) swimmer, Pachydiscus lived in Occurrence: open seas. REMARK The specimen is Informal name: Ammonite preserved in limestone but open-coiled retains patches of the whorls original shell. ribs with original shell tubercles material Typical diameter 10cm (4in) Pachydiscus sp.; Late Distribution: Worldwide Occurrence: Cretaceous; Canada. Range: Late Cretaceous Group: AMMONITIDA Subgroup: CRIOCERATITIDAE Crioceratites The shell of Crioceratites is so loosely coiled that the whorls are not in contact. The whorl size increases rapidly. Stronger ribs carrying tubercles are separated by two to three weaker, finer ribs with no tubercles. The venter is rounded. HABITAT This genus was adapted to a predatory swimming habit in moderately deep, shelf seas. REMARK The loosely coiled morphology evolved many times in the ammonoids and nautiloids. fine ribs Crioceratites sp.; Early Cretaceous; South Africa. Range: Early Cretaceous Distribution: Worldwide","152 | Invertebrates Group: AMMONITIDA Subgroup: ACANTHOCERATITIDAE Informal name: Ammonite strong, rounded Mammites tubercles The shell is robust with a squarish whorl section coarse and a flattened venter. The suture is relatively ribbing simple. There are three rows of rounded tubercles on stout ribs. HABITAT Mammites inhabited phosphatic the shallow warm shelf seas of internal cast the Late Cretaceous. REMARK They are mined commercially in Morocco. They occur as oyster-encrusted phosphatic internal casts, often in nodules. Mammites nodosoides (Schl\u00fcter); Late Cretaceous; Morocco. Typical diameter 15cm (6in) Distribution: Worldwide Occurrence: Range: Late Cretaceous Group: AMMONITIDA Subgroup: DESMOCERATITIDAE Informal name: Ammonite Aioloceras hollow, calcite-lined chamber The shell is discoidal with a smooth, arched venter. The outer original whorl covers approximately half nacreous the preceding one. The ribbing is shell rounded and indistinct and confined to the inner whorls. The sutures are frilled and very detailed. HABITAT Aioloceras inhabited Sliced section complex, frilled sutures the shallow, warm shelf seas of the Early Cretaceous. Polished REMARK This species is mined Aioloceras besairiei internal cast commercially in Madagascar where (Collignon); Early they are often sliced and polished Cretaceous; Madagascar. for export. Typical diameter 20cm (9in) Range: Early Cretaceous Distribution: Worldwide Occurrence:","Invertebrates | 153 Group: AMMONITIDA Subgroup: PLACENTICERATIDAE Informal name: Ammonite Placenticeras tabulate venter This Late Cretaceous genus grew to a considerable size compressed (up to 50cm\/20in) \u2013 the specimen shown here lacks the profile living chamber of the ammonite, which, in life, would have comprised almost another whorl. The highly living chamber compressed, very involute shell has a very narrow broken away venter and a thick, nacreous shell. HABITAT Experiments in tanks with models of broken end of ammonite shells indicate that Placenticeras, with its convoluted septum large size and very streamlined profile, was perhaps the fastest swimmer of all known ammonites, jetting Whorl profile through the water in pursuit of prey, or fleeing from reptiles and large fish. REMARK Several specimens recovered from the Western Interior Seaway of the USA display bite-marks from the repeated attacks of a giant marine reptile. Placenticeras meeki (B\u00d6hm); Late Cretaceous; USA. former position of aperture umbilicus smooth, almost flat flank faint ribs Distribution: Worldwide Typical diameter on flank 20cm (8in) Range: Late Cretaceous Occurrence:","154 | Invertebrates Group: AMMONITIDA Subgroup: EODEROCERATIDAE Informal name: Ammonite small, perfectly Promicroceras Asteroceras shell preserved shells of This limestone (known as Marston Marble) is Promicroceras composed largely of closely packed, small, but complete, shells of the ammonite original shell genus Promicroceras. A fragment of a Occurrence: larger genus, Asteroceros, is present on the corner of the block. Promicroceras\u2019 Informal name: Ammonite shell is evolute, and is ornamented by coarse, simple, straight ribs which Asteroceras obtusum form a forward-directed flange over (J. Sowerby); the venter. Lower Lias; Early HABITAT Marston Marble was formed Jurassic; UK. by the mass mortality of Promicroceras, resulting either from a major storm, or simple ammonite perhaps poisoning by an algal bloom. sutures REMARK The ammonite shells were chamber that rapidly buried in lime-mud, which housed the hardened into limestone. soft parts Marston marble; Typical diameter Lower Lias; Early 22cm (81\/2in) Jurassic; UK. Occurrence: Typical diameter 2cm (3\/4in) Range: Early Jurassic Distribution: Worldwide Group: AMMONITIDA Subgroup: AREITITIDAE Asteroceras Large, rather simply ornamented ammonites of this family are common in Early Jurassic sediments on a worldwide scale. The rather evolute shell carries curved ribs, and a keel is present on the venter. HABITAT Asteroceras lived at moderate depths in shelf seas, and was probably a slow swimmer, living by predation on small marine animals. REMARK The chambered part of this well-preserved shell has infilled with translucent brown calcite, and the living chamber with grey lime-mud. The shell has mostly broken away. Range: Early Jurassic Distribution: Worldwide","Group: AMMONITIDA Subgroup: ECHIOCERATIDAE Invertebrates | 155 Echioceras Informal name: Ammonite The shell is extremely evolute, with venter carries numerous visible whorls and a shallow low keel umbilicus. Short, straight ribs are present on the flanks, but do not pass on to the low-keeled venter. HABITAT This ammonite inhabited the shelf seas of the Early Jurassic. From the very evolute shell shape it is possible to infer that Echioceras was not adapted for fast swimming. It probably scavenged, or caught slow-moving prey. Typical diameter Echioceras sp.; short, straight ribs 6cm (21\/2 in) Lower Lias; on evolute shell Early Jurassic; UK. Occurrence: Range: Early Jurassic Distribution: Worldwide Group: AMMONITIDA Subgroup: AMALTHEIDAE Informal name: Ammonite Pleuroceras rib corded keel venter The shell is planate, with about a 25 per cent overlap, exposing many whorls and a relatively open umbilicus. The whorl section is quadrate with strong evenly situated radial ribs and a prominent corded keel on a flattened venter. HABITAT This was a small, fast-moving nektonic ammonite, only known from the shallow shelf seas of the northern hemisphere. REMARK This specimen is preserved in solid iron pyrite but retains a thin layer of its original nacreous shell. Pleuroceras spinatum Side view umbilicus View of venter Typical diameter (Brugui\u00e8re); Early Jurassic; 5cm (2in) Germany. Range: Early Jurassic Distribution: Europe, North America Occurrence:","156 | Invertebrates Group: AMMONITIDA Subgroup: ACANTHOCERATIDAE Informal name: Ammonite strong, intercalated, Mantelliceras long and short ribs The shell is involute, with a fairly simple small umbilicus. The whorl section aperture is rectangular, the venter flat. of large Alternately long and short ribs female shell are present on the flanks. HABITAT Mantelliceras and its relatives were probably poor swimmers, since they were not streamlined. They display strong sexual dimorphism in size, with the females (macroconchs) much larger. REMARK The genus is characteristic of the beginning of the Late Cretaceous in the northern hemisphere. Typical diameter broad venter Mantelliceras sp.; Lower 4.5cm (13\/4in) Distribution: Europe Chalk; Late Cretaceous; UK. Range: Cretaceous Occurrence: Group: AMMONITIDA Subgroup: HOPLITIDAE Informal name: Ammonite Euhoplites strong ornament The shell is moderately involute, and inflated of ribs and tubercles in profile. The flanks bear tubercles, from which arise bunched ribs. The venter has a narrow groove. living chamber broken away HABITAT The numerous ribs and tubercles, together with the rectangular profile of the whorl, would have offered much resistance to water, and prevented Euhoplites from swimming fast. REMARK In life the shell would have been three times the size of this fragment, which has missing whorls. Euhoplites opalinus Spath; Gault Clay; Early Cretaceous; UK. Typical diameter original nacre 3.5cm (13\/8in) shell preserved Range: Early Cretaceous pyrite preservation Distribution: Europe Occurrence:","Group: AMMONITIDA Subgroup: SCHLOENBACHIIDAE Invertebrates | 157 Schloenbachia ventral keel Informal name: Ammonite Schloenbachia is one of the most typical Late Whorl profile Cretaceous ammonites of Europe. It displays strong, rounded considerable variation in the development of ornament \u2013 tubercles some specimens are nearly smooth and very flat; others are fat, with tubercles. The strongly developed ventral keel is characteristic of the genus. Individuals can grow up to 25cm (10in) across. HABITAT Ammonites of this genus are thought to be fairly good swimmers. REMARK This specimen is preserved as a phosphatic internal cast. rows of well-developed Distribution: Europe, Greenland broken end tubercles on flanks of septum Typical diameter Schloenbachia varians 5cm (2in) (J. de C. Sowerby); Range: Late Cretaceous Lower Chalk; Late Cretaceous; UK. Occurrence: Group: AMMONITIDA Subgroup: BRANCOCERATIDAE Informal name: Ammonite Mortoniceras Mortoniceras potternense (Spath); Early Cretaceous; UK. The genus Mortoniceras is a very widespread form in Early Cretaceous sediments, and irregular tubercles may grow to 50cm (20in). The highly set on ribs characteristic shell form includes a strong keel on the venter and a evolute, squarish whorl section. open-coiling style HABITAT The genus was probably a poor swimmer, and would have swum slowly through the water. REMARK The specimen has been crushed into an elliptical shape in the rock. Typical diameter Distribution: Europe, Africa, USA strong ventral 8cm (31\/4in) keel Occurrence: Range: Early Cretaceous","158 | Invertebrates Group: AMMONITIDA Subgroup: DESHAYESITIDAE Informal name: Ammonite sinuous ribs Deshayesites rounded edge Deshayesites was an evolute, compressed ammonite, of venter whose shell carries a rather simple ornament of Occurrence: sinuous ribs. The ribs pass over the narrow, Informal name: Ammonite rounded venter. The genus was common in, and absolutely diagnostic of, the Aptian stage. Brown sandstone internal cast HABITAT The streamlined profile and weak ornament suggest that this genus was capable simple ribs of of fast movement through the water. varying size REMARK The specimen is preserved as an internal mould with traces of apparently irregular original shell. coiling pattern broken end of Nipponites mirabilis living chamber Yabe; Late Cretaceous; Japan. Typical diameter Deshayesites 4.5cm (13\/4in) forbesi Casey; Early Occurrence: Cretaceous; Russia. Range: Early Cretaceous Distribution: Worldwide Group: AMMONITIDA Subgroup: NOSTOCERATIDAE Nipponites Of all the Late Cretaceous ammonites that coiled in an irregular fashion, Nipponites was the most bizarre. At first sight the shell appears to be an irregular tangle of whorls. On closer inspection, however, it proves to be a 3D network of U\u2019s. It possesses a typical complex ammonite suture, and a simple ornament of ribs, and probably evolved from a helically coiled form (see p.159). HABITAT Nipponites Typical diameter probably lived as a 6cm (21\/2in) planktonic form, drifting through the mid-level or upper waters of the warm Late Cretaceous seas, and feeding on small animals which it caught with its tentacles. Range: Late Cretaceous Distribution: Japan, USA","Group: AMMONITIDA Subgroup: NOSTOCERATIDAE Invertebrates | 159 Bostrychoceras Informal name: Ammonite In this genus, and in the closely related family Bostrychoceras sp.; Turrilitidae, the coiling of the shell has become Late Cretaceous; helical (like a snail or gastropod), in contrast to Germany. the planispiral, flat coiling of most ammonites. Although superficially similar to gastropods, early spiral whorls such fossils are readily identifiable as ammonites from the characteristic suture fine, closely lines. In Bostrychoceras, the coiling is spaced ribs loose, so that successive whorls are not in contact. The simple ornament of fine, whorls not in closely spaced ribs is interrupted on the contact living chamber by the development of tubercles. The living chamber is living chamber U-shaped, and the aperture was curves directed forwards in life, so that forwards the protruding tentacles would not have been in contact with simple the sea bed below. aperture HABITAT Palaeontologists believe that this genus was probably planktonic, floating in the open ocean, and feeding on small animals in the water column. The very widespread distribution accords quite well with this theory, since ocean-going species are commonly of global occurrence. Another possibility is that they were bottom dwelling and moved along the seafloor hunting for small prey rather like an octopus. REMARK Bostrychoceras is most often found as small pieces of broken whorls, the ornamentation of which allows identification. Yellow limestone cast Typical diameter Distribution: Worldwide Occurrence: 14cm (51\/2in) Range: Late Cretaceous","160 | Invertebrates Group: AMMONITIDA Subgroup: BACULITIDAE Informal name: Ammonite fragment of Baculites chambered shell complex suture In this Late Cretaceous genus, only the very earliest part of the shell remained coiled; the latter part traces of suture grew into a straight shaft. Baculites can occur in vast numbers at some localities, often to the virtual exclusion of other species, and could grow to over a metre (39in) in length. HABITAT The mode of life of these straight ammonites is controversial; some palaeontologists believe they lived upright in the water, with the tentacles on the sea bed foraging for food, while others think they had horizontal orientation and lived closer to the surface of the sea. living chamber Typical length 10cm (4in) Baculites sp.; Calcaire a Baculites; Late Cretaceous; France. Range: Late Cretaceous Distribution: Worldwide Occurrence: Group: AMMONITIDA Subgroup: SCAPHITIDAE Informal name: Ammonite Jeletzkytes fine ribs tubercles original The family Scaphitidae represents a different design nacreous shell of Late Cretaceous uncoiled ammonite, in which the chambered early whorls are tightly coiled in the usual fashion, but the living chamber, comprising a short, straight shaft and a terminal hook, is shaped like a shepherd\u2019s crook. HABITAT The shell form of Jeletzkytes suggests it was unable to swim actively, but could use gas and liquid in its chambered shell to alter its buoyancy, and thus the position in the water column, in common with other ammonite genera. REMARK This specimen was preserved in a mudstone concretion full of small bivalve molluscs. Typical diameter Jeletzkytes nebraskensis body chamber 10cm (4in) (Owen); Late Cretaceous; Occurrence: USA. Range: Late Cretaceous Distribution: Worldwide","Invertebrates | 161 BELEMNITES AND SQUIDS BELEMNITES AND SQUIDS belong to a strong, usually cylindrical, calcite guards diverse group of cephalopods, which that preserved well, and occur abundantly include the living squid, cuttlefish, and in Mesozoic marine rocks. Squids possess octopus. The group is characterized by an an internal support called a pen, which internal, chambered shell enclosed entirely is made of proteinaceous chitin. This is by soft, muscular tissues. Many forms have only rarely preserved. However, in a hard internal support structure, made of a few instances, the soft tissue has been calcium carbonate or protein, known as preserved, and an entire squid, complete the pen or guard. Belemnites possessed with tentacles, is recognizable. Group: BELEMNITIDA Subgroup: BELEMNITIDAE Informal name: Belemnite Acroteuthis blunt termination The large, stout guard tapers to a blunt posterior end. The cylindrical cavity (alveolus) is deep. Grooves are present on the sides. HABITAT This marine creature was probably Acroteuthis lateralis (Phillips); Speeton Clay; a slow swimmer. Early Cretaceous; UK. REMARK The surface of the guard is worn deep often worn by erosion to show clearly surface of alveolus the concentric \u201conion skin\u201d layers of guard calcite that make it up. Typical length 50cm (20in) Distribution: Europe grooves Range: Early Cretaceous Occurrence: Informal name: Belemnite Group: BELEMNITIDA Subgroup: BELEMNOPSEIDAE part of guard Hibolites clay matrix housing alveolus The guard is long, slender, and delicately constructed, with a slightly bulbous posterior end. A strong, narrow groove is present near the anterior margin on the ventral side. This is fragile and often broken in the fossil state. HABITAT This slender belemnite swam in the Early Cretaceous seas. Hibolites jaculoides bulbous Typical length 30cm (12in) Swinnerton; Speeton Clay; posterior Early Cretaceous; UK. Distribution: Northern hemisphere Occurrence: Range: Middle Jurrasic\u2013Late Cretaceous","162 | Invertebrates Subgroup: BELEMNOPSEIDAE Informal name: Belemnite Group: BELEMNITIDA Neohibolites chambered phragmocone The guard of this small belemnite is slender and spindle shaped, preserved as translucent, phragmocone sits amber-coloured calcite. It has a deep, rounded in the alveolus of alveolus and an anterior groove. The proostracum the guard is a tongue-shaped extension at the front of the phragmocone. HABITAT Neohibolites lived in vast numbers, hunting small prey in the warm shelf seas of the mid-Cretaceous. REMARK The separate chambers of the phragmocone on this specimen are still visible. Neohibolites was a very common fossil in the Albian clays of Europe. Neohibolites minimus Typical length (Miller); Gault Clay; 23cm (9in) Early Cretaceous; UK. Range: Cretaceous Distribution: Worldwide Occurrence: Group: BELEMNITIDA Subgroup: CYLINDROTEUTHIDIDAE Informal name: Belemnite blunt tip Pachyteuthis worn surface of guard chambered The guard of this large, stout belemnite tapers evenly phragmocone to a blunt posterior termination. The broken surface preserved in of the guard displays its fibrous calcite construction. iron pyrites The rounded alveolus is deep and houses a large phragmocone, which consists of concavo-convex chambers now full of hardened mud. HABITAT Pachyteuthis lived as a predator or scavenger in the deeper-water shelf seas of the Late Jurassic. REMARK The phragmocone is well preserved in shiny iron pyrites. Pachyteuthis abbreviata (Miller); Kimmeridge Clay; Late Jurassic; UK. Typical length 50cm (20in) V-shaped Occurrence: Range: Middle\u2013Late Jurassic alveolus Distribution: Worldwide","Invertebrates | 163 Group: BELEMNITIDA Subgroup: BELEMNITELLIDAE Informal name: Belemnite Belemnitella Belemnitella mucronata The guard tapers only gently, and is (Schlotheim); Late terminated posteriorly by a tip called a Cretaceous; The mucron. The anterior part of the guard Netherlands. is paper-thin and houses a deep alveolus. The surface of the guard carries a network of intricately branching, shallow grooves, which are probably impressions created by the blood vessels in the soft tissues of the living belemnite. HABITAT Belemnitella deep alveolus swam in the shallower waters of the Late impression of veins Cretaceous Chalk on surface of guard sea, and used its hooked tentacles point on tip Typical length 40cm (16in) to catch small prey. of guard REMARK This is one of the belemnites which survived nearly to the end of the Cretaceous. It occurs in huge numbers at some localities in so-called \u201cbelemnite graveyards\u201d. Range: Late Cretaceous Distribution: Northern hemisphere Occurrence: Group: BELEMNITIDA Subgroup: CYLINDROTEUTHIDIDAE Informal name: Belemnite Cylindroteuthis Cylindroteuthis puzosiana apex of guard (d\u2019Orbigny); Oxford Clay; The guard is long and cylindrical, and tapers Late Jurassic; UK. gradually to a posterior point. The chambered phragmocone expands anteriorly. HABITAT This genus lived as a predator in the deeper parts of shelf seas. REMARK This is one of the largest species of belemnite, growing up to 25cm (10in) in length. alveolus of guard long, cylindrical guard Typical length 25cm (10in) Occurrence: Range: Middle\u2013Late Jurassic Distribution: Europe, N. America","164 | Invertebrates Group: Not applicable Subgroup: Not applicable Informal name: Belemnite limestone Belemnite limestone Treuchtlinger marble; Late Jurassic; Germany. This cut and polished piece of marine shelly limestone shows a belemnite in cross-section. It illustrates well the massive construction of the belemnite guard, alveolus composed of the mineral calcite (calcium carbonate). concentric growth rings Belemnites show fine, radially arranged, calcite crystals, and display strong, concentric growth lines. The V-shaped space at the anterior end of the guard is called the alveolus, and it housed the chambered phragmocone, used for buoyancy control by the belemnite in life. HABITAT Various belemnites would calcite guard of shell fragments phragmocone have had differing lifestyles, although Hibolites sp. in limestone all would have been marine dwellers. REMARK The term \u201cmarble\u201d is loosely applied to any polished limestone. Range: Triassic\u2013Cretaceous Distribution: Worldwide Occurrence: Group: TEUTHIDA Subgroup: TRACHYTEUTHIDIDAE Informal name: Belemnite Trachyteuthis growth lines on surface Only the guard of this genus has ever been found preserved as a fossil. The outline is an elongated oval with a lobe present on each side. On the dorsal surface growth lines are visible. HABITAT This animal probably resembled flattened guard a cuttlefish in its life habits, living on the sea resembling cuttlebone bed and preying on crustaceans. REMARK It is open to debate whether this genus is closer to the squid or cuttlefish in affinity. Trachyteuthis sp.; Solnhofen Limestone; Late Jurassic; Germany. Typical length 25cm (10in) limestone Occurrence: Range: Late Jurassic Distribution: Europe","Invertebrates | 165 Group: BELEMNITIDA Subgroup: BELEMNOTEUTHIDAE Informal name: Extinct squid Acanthoteuthis arms with head region small hooks The head region carries ten arms, on which hooks are present. The anterior part of the body is called the mantle, and has two fins \u2013 very much like a living squid. The hind- most part of the animal is the chambered phragmocone, which tapers posteriorly. At the end, a thin guard is sometimes preserved. HABITAT Acanthoteuthis lived in the open sea at a moderate depth, and swam by jet propulsion (water expulsion from the mantle) in exactly the same way as squid do in the present day. lt used its hooked and suckered arms to catch prey. REMARK This specimen displays a very rare phenomenon in the fossil record \u2013 the preservation of soft parts, which normally would decay and be completely lost. This type of preservation is caused by rapid burial of the animal in stagnant, oxygen-free water, where scavengers and most bacteria cannot live. The belemnite\u2019s soft parts are replaced by calcium phosphate. Acanthoteuthis chambered mantle with antiqua (Pearce); phragmocone two fins Oxford Clay; Distribution: Europe Late Jurassic; UK. Occurrence: Typical length 12cm (5in) Range: Late Jurassic","166 | Invertebrates CRINOIDS CRINOIDS, POPULARLY known as plates called columnals. At the top of sea lilies and feather stars, possess the stem is a swollen cup or calyx, to a massive calcite skeleton, and were which the arms are attached. The arms so abundant in the Palaeozoic seas are used to filter food from the water. that their remains formed vast Soon after death, the entire skeleton thicknesses of limestone. Most crinoids normally falls apart into small, separate are attached to the sea bed by a flexible plates called ossicles. In contrast, stem, circular or pentagonal in section, well-preserved crinoids are rare and made up of numerous disc-like and beautiful fossils. Group: MONOBATHRIDA Subgroup: SCYPHOCRINITIDAE Informal name: Sea lily Scyphocrinites feathery arms This large crinoid has a 3m (10ft) long stalk with an ornamented Two cups cup and arms extending a further 30cm (12in). The stem is circular in cross-section, reducing in diameter away from the crown and terminating in a large, globular lobolith. This is hollow, divided into compartments and composed of tangled cirri (fine tendrils) in some species, or small interlocking plates in others. HABITAT This would explain their wide geographic distribution. However, recently this idea has been challenged by the suggestion that they lived on the sea floor and the lobolith acted as a drag anchor. REMARK Scyphocrinites itself is restricted to Silurian rocks. This lobolith (right) is a plate lobolith from the early Devonian and belongs to a close relative of Scyphocrinites. calyx or cup wall of stem small plates attachment Scyphocrinites elegans stalk (Zekner); Late Silurian; Morocco. Lobolith Typical cup diameter 7.5cm (3in) Range: Silurian Distribution: Europe, N. America Occurrence:","Group: CLADIDA Subgroup: CUPRESSOCRINITIDAE Invertebrates | 167 Cupressocrinites Informal name: Sea lily This robust crinoid has a cylindrical stem, compact crown and a large, conical cup made up of ten large plates in two alternating circles. cup made of ten The short arms, five in number, are large plates unbranched and triangular in shape. They fit together closely to form a cylindrical short, pointed crown. stem HABITAT The typically robust form of this genus is perhaps related to the rough, current-swept, environment in which it lived, where more delicate forms would not have survived. REMARK The ancestry and relationships of Cupressocrinites are not well understood. Cupressocrinites crassus Typical cup diameter (Goldfuss); Crinoiden Schichten; 2.5cm (1in) Middle Devonian; Germany. Occurrence: Range: Devonian Distribution: W. Europe Informal name: Sea lily Group: CLADIDA Subgroup: CYATHOCRINITIDAE Cyathocrinites symmetrically branching arms Cyathocrinites has a cylindrical stem made up of numerous disc-shaped columnals. The bowl-shaped cup includes a few, smoothly rounded plates, and the narrow arms branch regularly to form a large, complex crown composed of many small units. HABITAT This genus lived in calm, shallow water, which provided an abundant supply of food. conical cup plated large complex anal tube crown Typical cup diameter 8mm (5\/16in) broken stem Cyathocrinites monile Distribution: Europe Salter; Wenlock Limestone; Range: Silurian\u2013Carboniferous Middle Silurian; UK. Occurrence:","168 | Invertebrates Group: SAGENOCRINIDA Subgroup: SAGENOCRINIDAE Informal name: Sea lily Sagenocrinites short, free arms The stem of Sagenocrinites is cylindrical and composed of broad numerous, very thin columnals. crown Its crown is very broad and oval in shape. The polygonal arm bases plates of the lower arms forming display clear growth lines part and form part of the cup. of cup The free parts of the arms are short and made up of many small plates. HABITAT The very compact form of this species suggests that it had adapted to relatively turbulent sea-bed conditions. stem of very thin columnals Sagenocrinites expansus Distribution: Europe, N. America Typical cup (Phillips); Wenlock diameter Limestone; Middle 2.5cm (1in) Silurian; UK. Occurrence: Range: Middle Silurian Group: UNCLASSIFIED Subgroup: UNCLASSIFIED Informal name: Crinoidal limestone Clifton Black Rock crinoid stem This striking black limestone contains a length of crinoid stem and many small crinoid ossicles in the background. The structure of the stem is well shown: it is made up of short columnals of even height, and has a large central cavity running along its length, now full of the limestone. HABITAT Crinoidal large central cavity limestone forms from the detritus washed from a reef. REMARK The black colour is due to bitumen. Typical cup diameter 4cm (11\/2in) Clifton Black Rock; Carboniferous Limestone; Carboniferous; UK. Range: Carboniferous Distribution: UK Occurrence:","Group: MONOBATHRIDA Subgroup: ACTINOCRINITIDAE Invertebrates | 169 Actinocrinites base of free arm Informal name: Sea lily domed top This well-preserved cup is typical of cup of many crinoids of the subclass Camerata. The large, rigid, Side view globular cup is made up of many polygonal plates, clearly Actinocrinites parkinsoni outlined on this specimen. These Wright; Carboniferous plates are arranged into several Limestone; Early rings at the base, above the point of Carboniferous; UK. attachment to the stem. Above this point, the plates of the lower arms Top view form a more irregular mosaic pattern, passing out to the five projecting stumps curved of the arms. The domed upper surface of the surface cup consists of fairly large plates. The stem is between circular and includes many very short columnals. arms In the Early Carboniferous sea, current action could cause such large drifts of crinoidal debris that they became a major constituent of the limestone. A separate artificial classification has been developed for isolated stem segments. HABITAT Actinocrinites lived on reefs in deep water, anchored to the sea bed by a root-like structure. Its short, simple arms trapped small food particles. Crinoidal limestone polygonal plates Range: Carboniferous stem segments Typical cup diameter Distribution: Worldwide 4cm (11\/2in) Occurrence:","170 | Invertebrates Group: ROVEACRINIDA Subgroup: SACCOCOMIDAE Informal name: Feather star globular cup Saccocoma This is a delicately constructed, stemless crinoid, with a small, globular cup. The arms branch once to give a total of ten. The lower parts of the arms have small wing-like extensions; the upper parts have long, narrow side-branches. HABITAT Saccocoma was free-living, and probably able to tolerate variations in salinity. REMARK This species is one of the most common fossils in the Solnhofen Limestone. branched arms Typical cup diameter Saccocoma tenella Occurrence: 2cm (3\/4in) (Goldfuss); Solnhofen Limestone; Late Jurassic; Germany. Range: Late Jurassic Distribution: Worldwide Group: CYRTOCRINIDA Subgroup: SCLEROCRINIDAE Informal name: Sea lily Torynocrinus end of cup This curiously shaped crinoid has arms set at right-angles arm attachment to its cup, which is shaped like a spoon. The stem-like point extension is actually formed from elongated cup places, and attached directly to a holdfast. HABITAT Torynocrinus lived attached to pebbles by a holdfast, and inhabited shallow, turbulent waters. REMARK The cyrtocrinids are squat, compact crinoids, locally common in Cretaceous rocks. point of Distribution: Europe elongated attachment base of cup to root Typical cup diameter 8mm (5\/16in) Torynocrinus canon (Seeley); Hunstanton Occurrence: Red Rock; Early Cretaceous; UK. Range: Late Jurassic\u2013Early Cretaceous","Group: COMATULIDA Subgroup: PTEROCOMIDAE Invertebrates | 171 Pterocoma Informal name: Feather star This comatulid or feather scar has long, a small cup, which bears ten long, feather-like feather-like arms of equal length. arms Each of these has a row of little branches (pinnules) on either side. Pterocoma It possessed a stem only in the pinnata earliest stages of development. (Schlotheim); Solnhofen HABITAT Pterocoma was a Limestone; free-swimming crinoid, advancing Late Jurassic; with graceful movements of the Germany. arms, like its living relatives. REMARK Comatulids are rarely Occurrence: found as entire specimens. small, centrally Distribution: Europe, Asia placed cup Typical cup diameter 1.5cm (5\/8in) Range: Late Jurassic\u2013Late Cretaceous Group: ENCRINIDA Subgroup: ENCRINIDAE Informal name: Sea lily Encrinus crown, with ten tightly closed arms The long, cylindrical stem of this crinoid long, round stem includes regularly spaced, swollen columnals. The crown is squat and compact; the plates are large and swollen. Each arm branches once at the base to give a total of ten short, sturdy arms. HABITAT Encrinus lived in Encrinus liliiformis shallow seas. Lamarck; Muschelkalk; REMARK This creature could splay Middle Triassic; Germany. its arms to form a feeding fan. Plankton, entrapped in the fan, were conveyed to the mouth along the grooves that lie inside the arms. When threatened, the arms closed tightly together in a defensive movement. Typical cup diameter 2.5cm (1in) Range: Middle Triassic Distribution: Europe Occurrence:","172 | Invertebrates Group: ISOCRINIDA Subgroup: PENTACRITINIDAE Informal name: Sea lily Pentacrinites pentagonal stem This distinctive crinoid has a long, pentagonal stem, with no root structure at the base. Regularly spaced whorls of fine branches (cirri) arise from the stem. The cup is small and inconspicuous. The fan-shaped crown is made up of multi-branched arms and many small pinnules (branches). HABITAT Masses of Pentacrinites are commonly found preserved under large pieces of fossil wood, leading to the belief that it was pseudopelagic (living in the open sea), in colonies attached to the underside of floating logs. The dispersed debris is locally abundant around logs and formed thin sheets of limestone. small cup at fan-shaped base of crown crown Pentacrinites fossilis Blumenbach; Lower Lias; Early Jurassic; UK. whorls of cirri rising from stem Typical cup diameter Four 1.5cm (5\/8in) Pentacrinites Range: Jurassic Distribution: Europe, N. America Occurrence:","Invertebrates | 173 Group: MILLERICRINIDA Subgroup: APIOCRINITIDAE Informal name: Sea lily Apiocrinites broken base of arms This stoutly constructed crinoid has a narrow, cylindrical, tapering stem with a conical, large, bulbous irregularly shaped root cemented at the base. cup made of The bulbous cup is made up of enlarged columnals, two cycles of cup places, and the separate plates bases of the arms. The arms branch once, symmetrically, to give an elegant fan-shaped cycle of crown with ten arms in total. radial plates HABITAT Apiocrinites lived attached to hard, cycle of basal plates current-swept pavements on the Jurassic sea floor. lt filtered food from the water with its arms. Apiocrinites REMARK Remains of this species are found elegans (Defrance); most commonly as separate discoidal cup Bradford Clay; plates or columnals. The surface of the stem Middle Jurassic; UK. and the holdfast are often colonized by bryozoa and serpulid worms. Typical cup diameter column base stem cemented 3cm (11\/4in) attachment to sea floor Range: Jurassic\u2013Cretaceous conical root Distribution: Europe, Africa, N. America Occurrence: Group: UINTACRINIDA Subgroup: MARSUPITIDAE Informal name: Sea lily Marsupites branching Marsupites arms testudinarius The cup is large and globular, comprising 11 (Schlotheim); large, thin, polygonal plates, which have a Upper Chalk; Late radially arranged ornament. There is no stem, Cretaceous; UK. but in its place sits a large pentagonal plate. The arms are long and very narrow and branch to give a total of ten. HABITAT The adult Marsupites nestled in chalky mud on the sea floor, and strained food using large cup plates its arms. The larval central form was planktonic. pentagonal plate, without stem REMARK The large, Occurrence: separate cup plates are distinctive fossils and are used as zonal markers Typical cup in western Europe. diameter 3.5cm (12\/5in) Range: Late Cretaceous Distribution: Worldwide","174 | Invertebrates Group: UINTACRINIDA Subgroup: UINTACRINIDAE Informal name: Sea lily Uintacrinus Uintacrinus socialis Grinnell; Niobrara Chalk; This crinoid has no stem, but has a very large and Late Cretaceous; USA. globular cup, composed of many small, polygonal plates. The bases of the arms are incorporated in the cup, and the arms themselves are very narrow and greatly elongated, reaching up to 1.25m (50in). HABITAT Crinoids of this genus lived in soft, muddy areas of the sea floor, using their very long arms to catch plankton. REMARK Fossilized remains of Uintacrinus are usually found in the form of separate plates. large, globular cup Typical cup diameter 4.5cm (13\/4in) base of long, fragments Range: Late Cretaceous narrow arms of arms Distribution: Worldwide Occurrence: Group: ISOCRINIDA Subgroup: ISOCRINIDAE Informal name: Feather star Isocrinus columnal cirrus attachment scar Isolated crinoid stem segments consisting of up to a dozen columnal ossicles are a common occurrence in almost every Jurassic marine sediment. In some horizons they are sufficiently abundant to form thin limestones. In section, isocrinid columnals are shaped like five-pointed stars, as opposed to the pentagonal stems of other related crinoids (see p.172). They also possess whorls of cirrae every 10\u201320 ossicles. The facets of the ossicles bear distinctive petaloid markings resembling starfish. HABITAT Isocrinus was a suspension-feeder, living in a shallow shelf sea, attached to the sea floor by a root-like holdfast. Typical cup diameter Isocrinus petaloid 1.5cm (5\/8in) basaltiformis marking (Miller); Early Jurassic; UK. ossicle Range: Triassic\u2013Miocene Distribution: Worldwide Occurrence:","Invertebrates | 175 ECHINOIDS THE ECHINOIDS possess a rigid, globular articulation of spines, which are skeleton (test) made up of columns of used for defence and sometimes for thin, calcite plates (ambulacrals and walking. Regular echinoids, which interambulacrals). The plates known forage on the sea bed, show radial as ambulacrals have small pores for symmetry; irregular echinoids, tube feet. All plates have swollen which usually burrow in soft tubercles for the ball-and-socket sea beds, show bilateral symmetry. Group: ECHINOCYSTITOIDA Subgroup: PALAECHINIDAE Informal name: Sea urchin Melonechinus numerous columns of polygonal plates The large, nearly spherical test is formed of many thick, polygonal plates. Both Upper surface ambulacrals and interambulacrals are of test made up of numerous plate columns. The mid line of the ambulacrals ridged ambulacral forms a distinct ridge. columns HABITAT Melonechinus Melonechinus lived in areas between multipora reefs in the (Owen & Carboniferous sea. Norwood); Early Carboniferous; Typical diameter 8cm (3in) USA. Range: Early Carboniferous Distribution: Worldwide Occurrence: Group: CIDAROIDA Subgroup: POLYCIDARIDAE Informal name: Sea urchin Plegiocidaris large interambulacral tubercles The circular, slightly flattened test comprises five paired, narrow narrow ambulacral plate columns and five ambulacra paired, broad interambulacra, made up of large plates with prominent position of tubercles. The hole on the top is apical disc the apical disc. Plegiocidaris HABITAT Plegiocidaris lived on coronata rocky sea floors, grazing on algae. (Schlotheim); REMARK Large spines were Weisser Jura; attached to the tubercles in life. Jurassic; Germany. Typical diameter 4cm (11\/2in) Occurrence: Range: Jurassic Distribution: Europe","176 | Invertebrates Group: CIDAROIDA Subgroup: ARCHAEOCIDARIDAE Informal name: Sea urchin Archaeocidaris The large test, which retains many spines on its surface, is crushed flat. The paired ambulacral columns are narrow, and the broad interambulacra are made up of four columns of plates, each of which carries a single, centrally placed tubercle. A long, narrow spine articulates with each large tubercle. Short spines form a felt-like covering over much of the test. The teeth and jaws are present on the underside, but are dissociated. scattered elements HABITAT The genus was of jaw system probably an omnivorous long, narrow spine browser, living on the open sea floor, protected by its long spines. large tubercle small, fine spines Lower surface position of Archaeocidaris whatleyensis of test mouth Lewis & Ensom; Carboniferous Limestone; Early Carboniferous; UK. Upper surface of test ambulacral column smooth spines felt-like covering of fine spines Typical diameter position of apical disc 8cm (3in) Range: Early Carboniferous\u2013Permian Distribution: Worldwide Occurrence:","Group: CIDAROIDA Subgroup: PSYCHOCIDARIDAE Invertebrates | 177 Tylocidaris large, club- Informal name: Sea urchin shaped spines The small test is circular in outline and underside slightly flattened. The ten columns of large interambulacral tubercles carry massive, club-shaped defensive spines. The central aperture on the base housed the jaw mechanism (known as Aristotle\u2019s Lantern) in life. HABITAT Tylocidaris lived as an omnivorous grazer on shells and sponges on the Chalk sea floor. REMARK Isolated spines and fragments of the test are quite common Chalk fossils. Typical diameter 3cm (11\/4in) large interambulacral position of Tylocidaris clavigera Range: Late Cretaceous\u2013Eocene tubercles mouth opening (K\u00f6nig); Upper Chalk; Late Cretaceous; UK. Distribution: Europe, N. America Occurrence: Group: CIDAROIDA Subgroup: CIDARIDAE Informal name: Sea urchin Temnocidaris Temnocidaris sceptrifera (Mantell); Upper Chalk; The nearly spherical test is made up of five paired Late Cretaceous; UK. columns of large interambulacral plates, each with a large conspicuous tubercle. The five paired narrow ambulacrum ambulacral columns are narrow and sinuous. The large, spindle-shaped spines attached large to the large interambulacral tubercles had interambulacral a rough, thorny surface in life. tubercle HABITAT Temnocidaris lived on the Chalk sea floor. It was an omnivorous scavenger, using its sharp teeth to rasp food. REMARK Tenmocidaris is very rarely preserved in its entirety. The apical disc is missing in this specimen. position of apical disc large primary Distribution: Europe Typical diameter spine 4.5cm (13\/4in) Range: Late Cretaceous Occurrence:","178 | Invertebrates Group: SALENIOIDA Subgroup: SALENIIDAE Informal name: Sea urchin Trisalenia large Trisalenia loveni tubercle (Cotteau); Late The circular flattened test of Cretaceous; Sweden. Trisalenia is capped by a very large, flat apical disc made up of two rings large, flat of plates, plus a single central plate apical disc and a hole in which the anus was off-centre situated in life. The large genital anus plates carry pores through which eggs and sperm were released. The Typical diameter 2cm (3\/4in) large interambulacral tubercles Occurrence: carried smooth, pointed spines. HABITAT Trisalenia lived among large granite boulders on the rocky shoreline that fringed part of southern Sweden during the Late Cretaceous. REMARK The family Saleniidae occurs commonly in marine Cretaceous sediments. Range: Late Cretaceous Distribution: Sweden Group: HEMICIDAROIDA Subgroup: HEMICIDARIDAE Informal name: Sea urchin large tubercles Hemicidaris long, tapering, smooth spines apical disc The test of Hemicidaris has a rounded outline from above, and a rather small apical disc. The ten columns of interambulacral plates each carry a very prominent tubercle bearing long, smooth, tapering spines. The ambulacra are narrow. HABITAT Hemicidaris lived among rocky outcrops on the sea bed, held by the sticky tube feet on its underside. It grazed hard surfaces using its five sharp teeth. REMARK This well-preserved specimen was buried rapidly by sediment. Typical diameter 3cm (11\/4in) smaller, short Hemicidaris intermedia Range: Middle Jurassic\u2013Early Cretaceous spines (Fleming); Coralline Limestone; Late Jurassic; UK. Distribution: Worldwide Occurrence:","Group: PHYMOSOMATOIDA Subgroup: PHYMOSOMATIDAE Invertebrates | 179 Phymosoma chalk matrix Informal name: Sea urchin The test is circular and numerous flattened. The areas occupied smooth spines by both the apical disc and the membrane around the mouth are very broad. The ambulacral and interambulacral tubercles are about the same size, and in life bore tapering, smooth, cylindrical or flattened spines. Isolated spines are common Chalk fossils. HABITAT Phymosoma lived on the Chalk sea floor, grazing on hard surfaces to obtain algae, sponges, and other soft organisms. Typical diameter 3cm (11\/4in) test with many Phymosoma koenigi tubercles (Mantell); Upper Chalk; Late Cretaceous; UK. Range: Late Jurassic\u2013Eocene Distribution: Worldwide Occurrence: Group: ARBACIOIDA Subgroup: ARBACIOIDAE Informal name: Sea urchin Coleopleurus apical disc genital pores The small test has a pentagonal outline, and is hemispherical in profile. The ambulacrals are broad and swollen and carry large tubercles. The interambulacrals are smooth and devoid of tubercles on the upper part of the test. The apical disc has five large genital pores, and a central opening in which the anus was enclosed. HABITAT This genus lived on hard, large tubercles on ambulacra rocky substrates in shallow water. REMARK The large, basally- situated ambulacral tubercles imply that Coleopleurus had stout spines in life. It is probable that these spines Coleopleurus smooth were used for stability, rather paucituberculatus interambulacra than for protection. Typical diameter (Gregory); Morgan Limestone; 2cm (3\/4in) Miocene; South Australia. Range: Miocene Distribution: Australia Occurrence:","180 | Invertebrates Group: ECHINONEOIDA Subgroup: CONULIDAE Informal name: Sea urchin Conulus small apical Side disc view The test is rounded or slightly pentagonal when viewed from above, and conical in side ambulacral interambulacral aspect. The base is flattened or concave. The plates with plates mouth was positioned centrally on the base, the anus on the edge of the base. The surface pores hole of the test bears very small tubercles, which in enclosing life carried a felt-like covering of small spines. mouth HABITAT Conulus ploughed through the Basal view soft mud of the sea floor. In certain thin stratigraphic levels tests are very common. Occurrence: Conulus albogalerus Leske; Upper Chalk; Late Cretaceous; UK. hole enclosing anus Typical diameter 3.5cm (13\/8in) Range: Late Cretaceous\u2013Paleocene Distribution: Worldwide Group: CLYPEASTEROIDA Subgroup: CLYPEASTERIDAE Informal name: Sand dollar Clypeaster Clypeaster aegyptiacus Michelin; Miocene; The large, thick test of Clypeaster has a rounded, Saudi Arabia. pentagonal outline, and a low, conical profile. On the upper surface the ambulacra are expanded to form distinctive petals which carry many elongated pores. The small, circular mouth is surrounded by jaws, and lies at the centre of the depressed base. The anus also lies on the lower surface near the posterior. The surface of the test is covered with small tubercles which, in life, bear short spines. HABITAT Clypeaster is a typical sand dweller, living partly or completely submerged in sand in shallow water, feeding on sediment. It is a \u201cliving fossil\u201d, and is found today in shallow, tropical seas. Typical diameter tiny tubercles large petals used 12cm (43\/4in) for respiration Range: Late Eocene\u2013Recent Distribution: Worldwide Occurrence:","Group: CLYPEASTEROIDA Subgroup: MELLITIDAE Invertebrates | 181 Encope Informal name: Sand dollar The sand dollar, Encope, is very flat and thin Upper surface of test in profile. The five petals are well developed but smaller than in Clypeaster (see five petals opposite). Each of the five ambulacra is perforated by an oval hole (a lunule) near the margin, which passes right through the test. A single, larger sixth hole is present in the posterior ambulacrum. HABITAT Encope lives buried in sand in shallow tropical water, often in large numbers. The lunules aid the animal in feeding on fine sediment. Typical diameter Encope micropora 9cm (31\/2in) Agassiz; Recent; Peru. very flat test lunule Occurrence: Range: Miocene\u2013Recent Distribution: N. & S. America Informal name: Sand dollar Group: CLYPEASTEROIDA Subgroup: ROTULIDAE posterior indentations Heliophora five ambulacral petals A very distinctive small African sand dollar. The test has a variable number of indentations along the posterior margin forming fragile, finger-like projections. HABITAT Heliophora lives buried just below the sediment surface in coastal lagoons and estuaries. REMARK This species is locally abundant along the west African coast. interambulacral plates Typical diameter Heliophora orbiculus four genital 3.5cm (13\/8in) (Linnaeus); Late Miocene; pores Morocco. Occurrence: Range: Miocene\u2013Recent Distribution: Africa","182 | Invertebrates Group: CASSIDULOIDA Subgroup: FAUJASIIDAE Informal name: Sea urchin Hardouinia broad, well-defined short petals plating The large test of Hardouinia is conical in profile with a flat base. The petals, which in life bore tube feet specialized for respiration, are short and broad, and very conspicuous. The interambulacral plates are low and broad. The mouth lies centrally on the lower surface and has five prominent projections, giving it a stellate outline. The anus is inset on the posterior side of the upper test. The surface originally carried short, fine spines. HABITAT This genus lived partially buried position of Hardouinia mortonis in sandy sediment, into which it burrowed anus (Michelin); Peedee Formation; with the aid of the short spines. lt Late Cretaceous; USA. swallowed the sand that it lived in to obtain nourishment. REMARK Hardouinia is common in sandy limestone faces, in the eastern USA. Juvenile specimens are much less conical in shape. Typical diameter 3.5cm (11\u20443in) Range: Late Cretaceous Distribution: N. America Occurrence: Group: HOLASTEROIDA Subgroup: HOLASTERIDAE Informal name: Sea urchin posterior end Echinocorys large, elongated The elongated test is large and conical in profile, apical disc often with a flattened top. lt has a covering of small tubercles. The base is flat, and the oval long mouth is positioned near the anterior petals border. In life, the spine cover was fine anterior end and short. It has a large, elongated Occurrence: apical disc and long petals. HABITAT This genus lived partially buried in mud or sand. It ploughed through this to find nutritious particles of sediment. REMARK Echinocorys is one of the most common of the Late Cretaceous Chalk echinoids. The top of the test is often broken. This is probably due to the attack of predators, such as fish. Typical diameter 7cm (23\u20444in) Echinocorys scutata Leske; Upper Chalk; Late Cretaceous; UK. Range: Late Cretaceous\u2013Paleocene Distribution: Worldwide","Group: SPATANGOIDA Subgroup: HEMIASTERIDAE Invertebrates | 183 Hemiaster posterior margin with anus Informal name: Heart urchin Heart-shaped in outline and oval in profile, large, sunken petals the test is covered in small, fine tubercles. The mouth is positioned on the flat base near the anterior margin and the anus is positioned on the posterior. The well-developed petals are set in grooves. The anterior margin is notched. HABITAT Hemiaster lives deeply buried in muddy sediment, feeding on mud, which it channels to its mouth via the anterior notch. REMARK Hemiaster was abundant in muddy sediments of the Cretaceous. Hemiaster batnensis Coquand; Fahdene Formation; Late Cretaceous; Tunisia. Typical diameter anterior notch of test fine tubercles 4cm (11\u20442in) Occurrence: Range: Cretaceous\u2013Recent Distribution: Worldwide Group: SPATANGOIDA Subgroup: SCHIZASTERIDAE Informal name: Heart urchin pores of Linthia etched plate petals boundaries Linthia was a rather small, compact heart urchin with a very strong, deep notch on the anterior margin, and conspicuous petals with large pores. Four large genital pores on the apical disc were used for the discharge of eggs and sperm. HABITAT This genus lived as a burrower in soft sediments. REMARK Weathering of the test surface of this particular specimen has revealed the boundaries between plates in places. Typical diameter Linthia sudanensis genital pores 7cm (23\u20444in) Bather; Kalanbaina in disc Formation; Early Occurrence: Range: Paleocene Paleocene; Republic of Niger. strong anterior notch Distribution: Northern Africa","184 | Invertebrates Group: SPATANGOIDA Subgroup: SCHIZASTERIDAE Informal name: Heart urchin Schizaster Block with complete and broken heart urchins The anterior petal in the heart urchin, Schizaster, is deeply inset and enlarged. The pores, which in life bear respiratory tube feet, are very conspicuous on the petals. HABITAT Schizaster lives deeply buried in muds. It uses its long tube feet as a funnel-like connection to the sea bed. Schizaster feeds on fine particles of sediment. REMARK This group of entire and broken individuals probably represents a storm- swept residue \u2013 the result of waves scouring deeply buried urchins from their burrows. Most specimens are preserved as internal moulds, as the shell usually breaks away. well-developed petals clay matrix pores of respiratory tube feet Schizaster branderianus large anterior Typical diameter Forbes; Barton Beds; petal 2.5cm (1in) Middle Eocene; UK. Distribution: Worldwide Occurrence: Range: Eocene\u2013Recent","Group: SPATANGOIDA Subgroup: MICRASTERIDAE Invertebrates | 185 Micraster Informal name: Heart urchin The Chalk heart urchin, Micraster, is Micraster coranguinum pointed posteriorly and has a strong (Leske); Upper Chalk; anterior notch. The five petals are Late Cretaceous; UK. narrow and fairly short. strong HABITAT This genus lived buried in even, fine tubercles anterior notch the soft mud of the Chalk sea floor, and channelled a stream of mud narrow, depressed petals into its mouth via the Occurrence: strong anterior notch. REMARK This species is one of the more advanced forms, occurring in the higher beds of the Chalk. Typical diameter 5cm (2in) Range: Late Cretaceous\u2013Paleocene Distribution: Worldwide Group: SPATANGOIDA Subgroup: LOVENIIDAE Informal name: Heart urchin Lovenia Upper surface posterior This heart urchin has an elongated, flattened test with a flat base. The petals are shallow and taper towards the margin of the test. In addition to the fine covering of tubercles, large, deeply inset tubercles are present on both sides of the test. These carry long, curved, protective spines. HABITAT Lovenia is a anus shallow burrower in sand, usually occurring in inshore marine deposits. REMARK The few large tubercles on the upper surface of this heart urchin make it very distinctive. flat large anterior base tubercles notch Lower surface crescent-shaped mouth Lovenia forbesi (Woods); Morgan anterior Typical diameter Limestone; Miocene; Distribution: Worldwide 2.5cm (1in) Australia. Occurrence: Range: Late Eocene\u2013Recent","186 | Invertebrates ASTEROIDS THE ASTEROIDS, which include many five ambulacral grooves, floored by of the species popularly called starfish, ambulacral and adambulacral ossicles, run are common marine animals and have along the midline of each arm. The grooves a long history extending back into the house the soft, muscular tube feet, which Ordovician. Most have five arms, although are used for walking, burrowing, and some species have more. The mouth is manipulating prey. Asteroids are rarely centrally placed on the underside, and preserved as complete specimens. Group: UNCLASSIFIED Subgroup: PALASTERICIDAE Informal name: Starfish Palastericus Palastericus devonicus ridge formed by ossicles Sturtz; Hunruckschiefer; of ambulacral groove This starfish has five short, Late Devonian; Germany. strap-like arms. All the ossicles, Occurrence: except those of the ambulacral Informal name: Starfish groove and mouth, are small and inconspicuous. The body is Pentasteria covered with short, fine spines. cotteswoldiae (Buckman); HABITAT Palastericus small Stonesfield Slate; lived by ingesting ossicles of Middle Jurassic; sediment and small upper surface UK. marine animals. border of large marginal ossicles REMARK The specimen Occurrence: shown here has been beautifully preserved in iron pyrites. Typical diameter 12cm (5in) Range: Late Devonian Distribution: Germany Group: PAXILLOSIDA Subgroup: ASTROPECTINIDAE Pentasteria The five arms are quite narrow and the disc is small. Large marginal ossicles form a broad, well-defined border to the asteroid. The upper surface of the disc is occupied by small plates, through which the large mouth ossicles can be clearly seen. HABITAT Pentasteria probably lived as a shallow Typical diameter burrower in sand. 10cm (4in) Range: Jurassic\u2013Early Cretaceous Distribution: Europe","Group: STENURIDA Subgroup: STENASTERIDAE Invertebrates | 187 Stenaster Informal name: Starfish This small and enigmatic form has been Upper surface variously classified as an ophiuroid and of starfish an asteroid. The five arms are short, the disc rather broad in form. The broad Stenaster obtusus ambulacral ossicles extend across (Forbes); Drummock the width of the arm. Group; Ordovician; UK. HABITAT This was a Lower surface marine-dwelling animal. of starfish REMARK The Starfish Bed at Girvan in Scotland, UK, rows of formerly yielded a large ossicles number of beautifully preserved starfish and other Typical diameter fossils. These starfish were 4cm (11\/2in) present as natural moulds, where the calcite skeletons had dissolved. A storm was probably responsible for the rapid deposition of sand which smothered the animals. Stenaster is a starfish with poorly understood relationships to other asteroids. Range: Ordovician Distribution: Europe, N. Africa Occurrence: Group: VELATIDA Subgroup: TROPIDASTERIDAE Informal name: Starfish Tropidaster Tropidaster pectinatus Forbes; Middle Lias; Early Jurassic; UK. This small form has five blunt, petal-shaped arms and very large, wide ambulacral conspicuous mouth places. The groove ambulacral groove is widely open, and broad adambulacral ossicles make up the underside of the arm. In life, these each bore a row of prominent spines. HABITAT This starfish dwelt underside of arm in shallow marine water. showing ambulacral REMARK The photograph ossicles shows two specimens, a juvenile and a fully grown adult, both displaying the underside. Typical diameter 2.5cm (1in) Range: Early Jurassic Distribution: UK Occurrence:","188 | Invertebrates Group: VALVATIDA Subgroup: G0NIASTERIDAE Informal name: Starfish pentagonal Metopaster small form ossicles The arms are very short and the disc is large large marginal (the body resembles a pentagonal biscuit). The ossicles form marginal ossicles are large, few in number, and broad border conspicuous; in life they bore small, granular Occurrence: spines. The marginals, which form the tips of Informal name: Starfish the arms, are elongated and triangular. The disc was covered with small, Stauranderaster coronatus polygonal ossicles. (Forbes); Lower Chalk; Late Cretaceous; UK. HABITAT Like its living relatives, Metopaster probably lived as a sediment marginals overlap feeder or scavenger on the Chalk sea floor. to increase REMARK Marginal ossicles of this genus flexibility are common fossils. disc made of large ossicles Occurrence: Metopaster parkinsoni (Forbes); Upper Chalk; Late Cretaceous; UK. Typical diameter 5cm (2in) Range: Late Cretaceous Distribution: Europe Group: VALVATIDA Subgroup: STAURANDERASTERIDAE Stauranderaster This starfish has long, narrow arms and a medium-sized disc, which was originally dome-shaped, but has collapsed in this specimen. This disc is made up of fairly large, rounded ossicles. The large marginal ossicles of the arms overlap, allowing greater flexibility. HABITAT This genus was probably a surface dweller on the Chalk sea floor, and either fed on sediment or scavenged dead material. long, narrow arms soft chalk matrix Typical diameter Distribution: Europe 10cm (4in) Range: Late Cretaceous","Invertebrates | 189 OPHIUROIDS THE OPHIUROIDS ARE commonly asteroids. They consist of a central called starfish or brittle stars. Closely column of vertebrae, covered by related to echinoids they possess five four rows of plates. The ambulacral long, often fragile, arms which radiate groove is covered in ophiuroids. Today, from a flat, nearly circular disc. These ophiuroids occur in vast masses on arms are very flexible, and quite the sea floor; similar quantities are different in structure from those of found in the fossil state. Group: OPHIURIDA Subgroup: OPHIODERMATIDAE Informal name: Brittle star Palaeocoma long, flexible arms The disc is small and pentagonal, small disc with with very long, sinuous arms with some large four rows of plates of almost equal plates size. It is made up of ten large, pear-shaped plates on the upper central mouth surface, and five on the lower. Palaeocoma HABITAT This brittle star lived on egertoni (Broderip); the silty sea floor. Middle Lias; Early Jurassic; UK. Typical disc Distribution: Europe diameter 2cm (3\u20444in) Occurrence: Range: Early Jurassic Informal name: Brittle star Group: OPHIURIDA Subgroup: APLOCOMIDAE long, highly flexible arms Geocoma small, rounded central disc The disc is small and nearly fine limestone circular, the arms long and matrix broad at the base. The upper surface of the disc is made Geocoma up of a fairly small number carinata of large plates. The lateral (Munster); plates of the arms bear Solnhofen short, fine spines; the Limestone; upper side arm plates Late Jurassic; are very small. Germany. HABITAT Geocoma Occurrence: lived in lime-mud. Typical disc diameter 2cm (3\u20444in) Range: Jurassic Distribution: Worldwide","190 | Invertebrates BLASTOIDS THE BLASTOIDS ARE a small, well- and deltoids. The five columns of defined group of echinoderms, which ambulacral plates are V-shaped, in life were attached to the substrate bearing short brachioles used for by a thin stem, and in which the filtering food from the water. These compact theca is shaped like a rosebud. fossils are locally common from the The theca is made up of three circles of Silurian to the Permian, in marine five plates, known as basals, radials, shales and limestones. Group: SPIRACULATA Subgroup: PENTREMITIDAE Informal name: Blastoid openings on Pentremites top of theca The small theca is biconical in form, and large, broad had a very small attachment point to the ambulacra stem at the lower end. The ambulacra are broad and V-shaped. The theca is Typical cup diameter made up of several very large plates, 2mm (1\/16in) and has several openings to the outside at its top end, through Occurrence: which eggs and sperm could pass. Informal name: Blastoid HABITAT This form lived Pentremites Deltoblastus attached to a hard substrate pyriformis permicus on the sea bed. J. Sowerby; (Wanner); Permian; REMARK Blastoids are locally Okaw Group; Early Indonesia. common in Carboniferous Carboniferous; USA. marine sediments. Typical cup diameter 1.5cm (3\/8in) Range: Early Carboniferous Distribution: USA Occurrence: Group: SPIRACULATA Subgroup: SCHIZOBLASTIDAE Deltoblastus The theca is conical and tall, and the five large ambulacra are sunken into its surface. Between the ambulacra, the five areas made of large plates have a groove along the midline. HABITAT This genus was attached to hard substrates on the sea bed. REMARK Blastoids occur in V-shaped abundance in the Permian regions of Timor in Indonesia, but in the rest of the world between ambulacra they all but vanished in large, broad the Late Carboniferous. ambulacral areas Range: Permian Distribution: Indonesia","Invertebrates | 191 CYSTOIDS CYSTOIDS SUPERFICIALLY resembled of short, unbranched limbs called crinoids in that they were attached to brachioles. In addition, they had the substrate by a stem, and possessed distinctive triangular pore structures on a swollen theca made up of a variable the plates, which were thought to have number of plates. Cystoids, however, been used for respiration. Cystoids are did not have true arms. Instead they found, very occasionally, in Middle filtered food from the water by means Ordovician to Devonian rocks. Group: PLEUROCYSTITIDA Subgroup: PLEUROCYSTITIDAE Informal name: Cystoid undersurface of theca, Dipleurocystis made up of small plates This fossilized cystoid has a flattened, stout marginal triangular-shaped theca and is frame broadest at the posterior margin, tapering anteriorly. The stem consists Typical cup diameter of many short, ridged columnals. The 1.5cm (3\/8in) mosaic covering of small plates on the undersurface is uppermost. Occurrence: HABITAT This Dipleurocystis genus lived with the rugeri (Salter); undersurface lying on Caradoc Series; the sediment, and with Ordovician; UK. its stem coiled around any suitable attachment. tapering stem Range: Ordovician Distribution: Worldwide Group: PLEUROCYSTITIDA Subgroup: PLEUROCYSTITIDAE Informal name: Cystoid Pleurocystites Pleurocystites filitextus Billings; Trenton Limestone; This well-preserved specimen displays very Ordovician; Canada. clearly the large plates on the upper surface of the theca, and the rather short, rapidly coiled stem tapering, coiled stem. The stem is broad and flexible close to the theca and composed of alternately large and small ossicles. Two long brachioles extend on either side of the centrally placed mouth. HABITAT Pleurocystites was a position of benthonic, filter-feeding organism. mouth Typical cup diameter large plates on 2cm (3\/4in) upper side of theca Range: Ordovician Distribution: Worldwide Occurrence:","192 | Invertebrates Group: GLYPTOCYSTITIDA Subgroup: CALLOCYSTIDAE Informal name: Cystoid theca with five Lepadocrinites ambulacra Lepadocrinites had an elliptically shaped theca, which is made up of a few rather large plates, with very large, rhomb-shaped respiratory pores. The five ambulacra are long, and in life bore numerous brachioles. The stem is elongated and tapering, and made up of ridged columnals, which are short near the theca but are longer on the stem. HABITAT In life, Lepadocrinites was attached to hard substrates on the sea floor by a root. Lepadocrinites quadrifasciatus Pearce; Wenlock Limestone; Silurian; UK. originally attached Distribution: UK long, tapering by root stem Range: Silurian Typical cup diameter 2.5cm (1in) Occurrence: Group: RHOMBIFERA Subgroup: CALLOCYSTIDAE Informal name: Cystoid flattened theca Pseudocrinites carrying brachioles The theca is strongly flattened and rhombic circular in outline, and has two respiratory pore narrow ambulacra that run around the margins and carry short, stout short, brachioles. The theca is made up of tapering a few very large plates. It has one stem or two very large, rhomb-shaped respiratory pores. The short, Pseudocrinites tapering stem culminates in bifasciatus a club-shaped root. (Pearce); Wenlock HABITAT This genus Limestone; lived as a filter feeder, Silurian; UK. attached to a hard surface, such as a shell or Occurrence: pebble, on the sea floor. Typical cup diameter Distribution: Europe, N. America 2.5cm (1in) Range: Late Silurian\u2013Early Devonian","Invertebrates | 193 CARPOIDS THE CARPOIDS, also known as They were probably ancestral to the Homalozoa, are a small but diverse group echinoderms, but not to the chordates of invertebrates ranging from Cambrian as was once thought. Carpoids were free to the Devonian. They possessed a fragile living, being able to move on the sea bed, skeleton with the distinctive fine calcite and had a large head and a short, flexible structure of echinoderms, but without tail. Gill slits (like those in fish) are a trace of their five-fold symmetry. conspicuous in some carpoid genera. Group: CORNUTA Subgroup: COTHURNOCYSTIDAE Informal name: Cornute Cothurnocystis Cothurnocystis elizae Bather; Drummuck The head is boot-shaped, and has three Group Starfish Bed; pointed projections. A frame of marginal Ordovician; UK. plates forms the border of the head, and the central area is made up of boot-shaped small plates; a single row of large head with gill slits are also present. The marginal frame tail is quite short and flexible. short, flexible tail HABITAT Cothurnocystis Occurrence: lived on the sea floor, and Informal name: Mitrate was probably able to pull Placocystites itself along with its tail. Typical cup forbesianus De Koninck; diameter 5cm (2in) Wenlock Limestone; Range: Ordovician Distribution: Scotland Silurian; UK. Group: MITRATA Subgroup: ANOMALOCYSTITIDAE spines on anterior end Placocystites head made up The head of this mitrate is flattened and of thin plates rectangular in shape. It is made up of large, wavy ridges thin, calcite plates, which bear fine, wavy on surface ridges. The anterior end has two rod-like appendages which are, in fact, spines. Occurrence: The mouth is placed centrally. HABITAT Placocystites lived on the surface of the sea bed, and used its flexible tail as a lever to haul itself about. REMARK The tail is missing in this specimen. Typical cup diameter 2cm (3\/4in) Range: Late Silurian Distribution: Europe","194 | Vertebrates VERTEBRATES AGNATHANS THESE EARLY, jawless fishes have an no paired fins. Most of the extinct forms ancient lineage, represented today by the were tadpole-shaped, swam by undulating lampreys and hagfishes. Living forms have their tails, and had thick plates and scales funnel-like, suctional mouths with rasping, for armour. They first appeared in marine horny teeth, used for scraping flesh. Unlike waters, then spread to fresh and brackish jawed vertebrates, agnathan gills face waters, dominating the Silurian and inwards from the gill arches. They have Devonian periods. Group: PTERASPIDIFORMES Subgroup: PTERASPIDIDAE Informal name: Pteraspid Pteraspis long Pteraspis rostrata rostrum Agassiz; Old Red The flattened head region of Sandstone; Devonian; UK. Pteraspis was enclosed by massive, bony plates, which may have been Head shield formed by scales fusing together. It had one middle dorsal plate, growth lines one rostral plate, and one ventral plate, plus a smaller lateral series. immovable The plates were punctuated lateral plate by sensory canals. The mouth, situated on the underside, was bony dorsal flanked by small plates which shield may have assisted suctional bottom feeding. The eyes were dorsal small and placed along the sides. spine base The tail, with its larger lower lobe, caused upward driving of the head when rising from the bottom. A massive bony carapace may have acted as a phosphate store during times of shortage. HABITAT Fossil remains of Pteraspis are often found in marine and freshwater deposits. Typical length 25cm (10in) Distribution: Europe, Asia, N. America Occurrence: Range: Early Devonian","Group: CEPHALASPIDIFORMES Subgroup: CEPHALASPIDAE Vertebrates | 195 Cephalaspis Informal name: Cephalaspid The small freshwater fish, Cephalaspis, had Cephalaspis whitei a bony dorsal head shield, with overlapping Stensio; Old Red scales covering the rest of its body. The Sandstone; eyes were sited on top, close to Devonian; UK. the midline, with the mouth on the underside. A middle dorsal area sensory plate and two lateral areas of polygonal area plates are thought to represent sensory areas. eye socket HABITAT Cephalaspis inhabited cornua directed freshwater pools or streams. towards the back notch Typical length 22cm (83\/4in) Head shield Occurrence: Range: Early Devonian Distribution: Europe Group: ANASPIDIFORMES Subgroup: BIRKENIIDAE Informal name: Anaspid Birkenia long, spindle- Birkenia elegans shaped body Traquair; Slot Burn The spindle-shaped body of this small fish is armoured Formation; Middle by deep, overlapping, articulated scales arranged in Silurian; UK. rows. A row of ridge scales runs along the top. The terminal mouth forms a vertical slit, surrounded by the smaller, less organized cranial scales. HABITAT Birkenia was a freshwater genus. dorsal scales tail scales head terminal mouth Typical length deep body Occurrence: 6cm (21\/2in) scales Range: Middle Silurian Distribution: Europe","196 | Vertebrates PLACODERMS THE PLACODERMS FORMED a of the body and tail was covered by diverse group of now-extinct fishes small scales. The moderate-to-large that had simple jaws armed with eyes were protected by a circlet of slicing plates. Typically, these fish lived bony plates. Placoderms lived in marine on the sea bed. They had a heavily and fresh water, from the Late Silurian armoured head shield connected to the Early Carboniferous. Most were to a trunk shield, which covered the moderately sized, but some grew to anterior part of the body. The rest 6m (20ft) in length. Group: ANTIARCHI Subgroup: BOTHRIOLEPIDAE Informal name: Antiarch Bothriolepis Bothriolepis canadensis Whiteaves; Escuminac Formation; This armoured fish had two dorsal and pelvic fins, and a Late Devonian; Canada. heterocercal tail. Its semicircular head shield and massive trunk shield were flattened from top to bottom. Pectoral common eye sockets appendages, more extended than those of semicircular head Pterichthyodes, were probably used for shield balancing the body on the substrate. long pectoral Paired sacs inside the trunk shield appendage may have functioned as lungs when freshwater lakes dried Body up. Soft part preservation shield indicates the presence of a spiral intestinal valve, like that of sharks. HABITAT Bothriolepis was principally a freshwater bottom-feeder but its fossil remains have been found in estuarine and marine deposits. REMARK Species of Bothriolepis have been described from every continent including Antarctica. Its success can be attributed to its heavy protective armour and its ability to adapt to a wide range of environments. Typical length 40cm (16in) Distribution: Worldwide bony trunk Range: Late Devonian shield Occurrence:","Group: ARTHRODIRA Subgroup: COCCOSTEIDAE Vertebrates | 197 Coccosteus eye socket Informal name: Arthrodire This predatory fish had a broad, flattened Dorsal skull, with eyes placed well forward on head shield the sides. The robust, powerful, slightly gaping jaws lacked true teeth but were armed with bony, shearing cusps, which wore down with use. HABITAT Coccosteus was an active predator that inhabited shallow freshwater lakes and rivers. REMARK Its wide geographic distribution suggests that it was able to tolerate salt water. Coccosteus cuspidatus Miller; Old Red Sandstone; Devonian; UK. Typical length 35cm (14in) Distribution: Europe, N. America joint with Range: Middle\u2013Late Devonian trunk Occurrence: Group: ANTIARCHI Subgroup: ASTEROLEPIDAE Informal name: Antiarch small head shield Pterichthyodes articulated appendage This small fish had a pair of armoured and jointed appendages, articulated with the massive trunk trunk, which may have been used for shield bottom crawling. The relatively small head was enclosed in a bony shield, Pterichthyodes with eyes on the top and jaws on the milleri (Agassiz); underside which may have been used Old Red as shovels. The massive trunk shield, Sandstone; with its flat undersurface, is covered Devonian; UK. with overlapping bony plates. Occurrence: HABITAT Pterichthyodes was a bottom feeder that lived in shallow freshwater lakes. REMARK The name Pterichthyodes, \u201cwinged fish\u201d refers to its large wing-like pectoral appendages. It was originally thought that they could be used to \u201cwalk\u201d on land, an interpretation now discounted. Range: Middle Devonian Body shield Typical length 15cm (6in) Distribution: UK","198 | Vertebrates CHONDRICHTHYANS CREATURES OF THIS CLASS are continuously replaced from behind, characterized by a cartilaginous being shed from the jaw margin or lost skeleton made up of tiny, calcified during feeding. Trace fossils (see p.42) prisms. Living examples include the ascribed to the group include spirally sharks, skates, rays, and rabbitfishes. coiled faecal remains and intestines. Cartilage is not usually preserved, so Chondrichthyans diversified from common fossils tend to be teeth, scales, Devonian origins to become very and dorsal-fin spines. Sharks\u2019 teeth are common in today\u2019s seas. Group: PETALODONTIFORMES Subgroup: PETALODONTIDAE Informal name: Petalodont Petalodus Petalodus acuminatus The anterior teeth of this predator have Agassiz; Yoredale a symmetrical, triangular crown, with a Beds; Early moderately high central cusp and Carboniferous; UK. pronounced cutting edge. Lateral teeth are shorter and less symmetrical. broadly triangular crown HABITAT Petalodus probably Anterior inhabited coral reefs. tooth constricted crown\/ root junction Typical length 3.5m (111\u20442ft) Range: Early Carboniferous\u2013Permian Distribution: Northern hemisphere deep root Occurrence: Group: EUGENIODONTIFORMES Subgroup: AGASSIZODONTIDAE Informal name: Shark Helicoprion small, juvenile teeth Helicoprion bessonowi The front teeth of Helicoprion grew in a spiral Karpinsky; Early containing up to 180 teeth, and unlike most Permian; Russia. sharks it retained its teeth even after growing new ones. The older teeth Tooth were housed in a cavity at the junction spiral of the lower jaws. Individual teeth consist of upright, triangular crowns over a projecting root. HABITAT Helicoprion was probably a mid-water marine predator. Range: Early Permian Estimated length large, mature teeth 5.5m (18ft) Occurrence: Distribution: Worldwide","Group: HYBODONTIFORMES Subgroup: ACRODONTIDAE Vertebrates | 199 Acrodus Informal name: Hybodont shark The dorsal fin of this hybodont shark was supported Acrodus nobilis by an extended spine, with coarse longitudinal ridges Agassiz; Lower Lias; (costae) on the side walls and a trailing edge covered Early Jurassic; UK. with small, tooth-like projections. A long basal part, inserted into the soft tissues of the back, was supported posterior margin by a fin cartilage. The fin itself cut through the water lateral face with and prevented rolling during swimming. The longitudinal costae underslung mouth was armed with a battery of robust teeth for crushing its food. Coarse ridges of each individual tooth radiate from the crown centre, providing additional abrasion. Anterior and posterior teeth are small; lateral teeth have greatly expanded crowns supported on robust roots. HABITAT Acrodus was a slow-swimming marine shark, living close to the sea bottom on a diet of molluscs and crustaceans. Dorsal fin spine unornamented inserted portion radiating Dentition ridges crowns of lateral teeth Range: Triassic\u2013Late Cretaceous small posterior Typical length 2.7m (9ft) teeth Occurrence: Distribution: Worldwide","200 | Vertebrates Group: SYNECHODONTIFORMES Subgroup: PALAEOSPINACIDAE Informal name: Palaeospinacid shark Palidiplospinax meeting-point teeth of of lower jaws lower jaw This was a small, probably slow-swimming shark, similar in shape to a dogfish. It had skeleton of a weakly calcified braincase, with a short gill arch snout, and underslung mouth containing multi-pointed teeth. These were vertebral ornamented by vertical ridges, with column crowns displaced in relation to the tongue. The high, central cusp was flanked by up to four pairs of lower, lateral cusplets. Teeth at the front were upright and symmetrical, whereas towards the back, symmetry decreased, cusplets became shorter, and central cusps became more inclined. The side walls of the short, dorsal-fin spine were smooth and enamelled, with round enamel projections at the base. Vertebrae were calcified and spool shaped, with a central perforation for the skeletal rod (notochord). Scales were simple and non-growing. HABITAT Palidiplospinax lived in shallow, marine environments, feeding on small fish and thin-shelled, bottom-dwelling invertebrates. Palidiplospinax dorsal-fin enniskilleni (Duffin spine and Ward); Lower Lias; Early Jurassic; UK. displaced vertebral centra Typical length 2.5m (8ft) Partial skeleton Range: Early Triassic\u2013Paleocene Distribution: Worldwide Occurrence:"]