| Cetiosauriscus | |
|---|---|
 | |
| Composite photo of the mountedholotype skeleton shortly before display in1905 | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Clade: | †Gravisauria |
| Clade: | †Eusauropoda |
| Genus: | †Cetiosauriscus von Huene,1927[2] |
| Species: | †C. stewarti |
| Binomial name | |
| †Cetiosauriscus stewarti | |
Cetiosauriscus (/ˌsiːtioʊˈsɔːrɪskəs/SEE-tee-oh-SOR-iss-kəs)[3] is agenus ofsauropoddinosaur that lived between 166 and 164 million years ago during theCallovian (Middle JurassicPeriod) in what is nowEngland. Aherbivore,Cetiosauriscus had – by sauropod standards – a moderately longtail, and longerforelimbs, making them as long as itshindlimbs. It has been estimated as about 15 m (49 ft) long and between 4 and 10 t (3.9 and 9.8 long tons; 4.4 and 11.0 short tons) in weight.
The only knownfossil includes most of the rear half of a skeleton as well as a forelimb (NHMUK PV R3078). Found inCambridgeshire in the 1890s, it was described byArthur Smith Woodward in 1905 as a new specimen of thespeciesCetiosaurus leedsi. This was changed in 1927, whenFriedrich von Huene found NHMUK PV R3078 and theC. leedsitype specimen to be too different fromCetiosaurus, warranting its own genus, which he namedCetiosauriscus, meaning "Cetiosaurus-like".Cetiosauriscus leedsi was referred to the sauropodfamilyDiplodocidae because of similarities in the tail and foot, and had the dubious or indeterminate species "Cetiosauriscus"greppini, "C."longus, and "C."glymptonensis assigned to it. In 1980, Alan Charig named a new species ofCetiosauriscus for NHMUK PV R3078 because of the lack of comparable material to the type ofC. leedsi; this species was namedCetiosauriscus stewarti. Because of the poor state of preservation of theCetiosauriscus leedsi fossil, Charig sent a petition to theInternational Commission on Zoological Nomenclature to instead makeC. stewarti the type species.Cetiosauriscus stewarti became the oldest confirmed diplodocid until aphylogenetic analysis published in 2003 instead found the species to belong toMamenchisauridae, and followed by studies in 2005 and 2015 that found it outsideNeosauropoda, while not a mamenchisaurid proper.
Cetiosauriscus was found in the marine deposits of theOxford Clay Formation alongside many differentinvertebrate groups, marineichthyosaurs,plesiosaurs andcrocodylians, a singlepterosaur, and various dinosaurs: theankylosaurSarcolestes, thestegosaursLexovisaurus andLoricatosaurus, theornithopodCallovosaurus, as well as some unnamedtaxa. ThetheropodsEustreptospondylus andMetriacanthosaurus are known from the formation, although probably not from the same level asCetiosauriscus.
The fossil later known asCetiosauriscus was originally ascribed to the genusCetiosaurus—one of the first sauropods to be named, in1842 bypalaeontologistRichard Owen, and one with a complicated history due to many unfounded referrals of species and specimens, involving almost all English sauropod specimens. Thetype species ofCetiosaurus has changed throughout history because of incomplete remains and the taxon's significance, and many aspects of its anatomy and relationships are still uncertain.Cetiosaurus was originally named to includeC. medius,C. brevis,C. brachyurus andC. longus, which span from theMiddle Jurassic to theEarly Cretaceous of various localities across England. As none of these species are truly diagnostic, andCetiosaurus is a historically and taxonomically important taxon, the more complete Middle Jurassic speciesC. oxoniensis named bygeologistJohn Phillips in1871 became the type species.C. glymptonensis was also named in the same publication by Phillips, but is less complete and of questionable validity.[4]
Another English taxon,Ornithopsis hulkei, was named in1870 by palaeontologistHarry Govier Seeley for vertebrae from the Early CretaceousWessex Formation, younger than the existing species ofCetiosaurus.[4][5] Seeley consideredOrnithopsis to be closely related toCetiosaurus, but different due to the internal bone structure.[5] An additional species,Ornithopsis leedsii was named in1887 byJohn Hulke for apelvis, vertebrae andribs collected byAlfred Nicholson Leeds, an English farmer and amateurfossil collector who throughout his life compiled numerous collections of fossils from the Oxford Clay.[6][7]O. leedsii, from theLate Jurassic, showed similarities to olderCetiosaurus oxoniensis as well as youngerO. hulkei.[6] It was described in more detail by Seeley in1889, where he consideredO. hulkei,C. oxoniensis andO. leedsii to all be in the same genus, bearing the nameCetiosaurus. ButnaturalistRichard Lydekker discussed with Seeley, before the publication of Seeley's 1889 paper, thatCetiosaurus andOrnithopsis were not the same taxon. Lydekker suggested that Wealden fossils (includingO. hulkei) belonged toOrnithopsis and the Jurassic remains (includingO. leedsii andC. oxoniensis) toCetiosaurus.[8] Lydekker in1895 changed his mind and referred the speciesO. leedsii toPelorosaurus (known already from the speciesP. brevis, once namedCetiosaurus brevis)—asP. leedsi—and referred the genus toAtlantosauridae.[9][A] Lydekker's classification of the species was not supported by later authors like palaeontologistArthur Smith Woodward in1905, who followed Seeley's classification scheme.[10]
The sauropod fossil today known asCetiosauriscus stewarti was discovered in May1898 by clay workers in the area aroundFletton to the south ofPeterborough and east of theGreat Northern Railway line. Pits in this region expose the fossil-richsedimentary rocks of themarineOxford Clay, which is of middleCallovian age and today regarded as one of the classicgeological formations of British palaeontology.[11] The sauropod fossil possibly stems from NPBCL pit No. 1, which was the northernmost pit operated by the New Peterborough Brick Company Limited, and which produced the most vertebrate fossils. The discovery was brought to the attention of Leeds, who, after excavation, took the sauropod specimen to Eyebury, the Leeds' family home. In mid-August, after some cleaning and repairing of the specimen, geologistHenry Woodward visited Eyebury and produced a life-sized drawing of the remains for presentation at the British Association for the Advancement of Science Meeting. Following this presentation, on 17 August 1898, Henry Woodward returned with American palaeontologistOthniel Charles Marsh, who considered the sauropod to be closely related to the North American taxonDiplodocus. Alfred Leeds offered the sauropod to theBritish Museum of Natural History (BMNH, now abbreviated as NHMUK) for £250, which would equate to about £30,529 in 2017.[7][12] The NHMUK had earlier in 1890 and 1892 bought the First and Second Collections of Alfred Leeds, respectively. Woodward, Keeper of Geology at the NHMUK, had "great pleasure" to recommend to the Trustees of the NHMUK the fossil be purchased. The purchase was sanctioned on 25 February 1899, along with the purchase of assorted other remains for just over £357 (~£43,596 in 2018[12]), where the Leeds sauropod gained theaccession number BMNH R3078 (now NHMUK PV R3078).[7]
The amount of material made NHMUK PV R3078 the most complete sauropod specimen from theUnited Kingdom, comparable only later to the "Rutland Dinosaur" (referred toCetiosaurus) discovered in 1967.[7][10][13] Known regions of the specimen include theforelimb,hindlimb andvertebral column. The forelimb lacks themanus (hand) and part of theradius andulna, although the hindlimb lacks only a few bones in thepes (foot) and fragments of thetibia,fibula andilium. The vertebrae known are four parts of dorsal vertebrae, the neural spines of thesacrum, multipleanteriorcaudal vertebrae (tail bones), and a series of 27 nearly complete vertebrae from the middle of the tail with associated or articulatedchevrons (ribs along the underside of the tail), although the vertebral series is not continuous.[7][10] A tail tip (NHMUK PV R1967) from the same locality, but a different individual was thought by palaeontologistAlan Charig in 1980 to belong toCetiosauriscus. The assignment of NHMUK PV R1967 toCetiosauriscus was considered unlikely in alternate studies by palaeontologistsFriedrich von Huene, Paul Upchurch andDarren Naish because of the lack of overlap and uncertain phylogenetic positions.[14][15][16][2] In1903, the skeleton was mounted as preserved in the British Museum, so it could be more easily compared with other mounted sauropods fromNorth America.[7][10] The mount ofCetiosauriscus was put on display just prior to the cast skeleton ofDiplodocus, and was displayed with the dorsal vertebrae NHMUK PV R1984 and some isolated teeth from acamarasaurid (possibly referable toCetiosauriscus[17]), making it the first sauropod skeleton mounted in the United Kingdom.[7]
NHMUK PV R3078 was referred in 1905 by Arthur Woodward to the speciesCetiosaurus leedsii, as it was from the same geologic formation as other specimens that were assigned toC. leedsii.[10] Woodward also referred the dorsal vertebrae NHMUK PV R1984 and the tail tip NHMUK PV R1967 to the species.[7][10] In1927, Huene briefly described the anatomy of the speciesC. leedsii, where he noted that it shared many similarities withHaplocanthosaurus and was most likely betweenCetiosaurus proper and the former genus. For this reason, Huene proposed the new genus nameCetiosauriscus for the species.[2] To the genus he referred the specimens NHMUK PV R1984–R1988 and NHMUK PV R3078.[14]
Huene (1927) assigned"Ornithopsis" greppini, which he had named in1922, to the genusCetiosauriscus. The known material, discovered in Late Jurassic (Kimmeridgian) deposits in theReuchenette Formation ofSwitzerland, includes dorsal and caudal vertebrae, forelimb bones, and a hindlimb and partial pes, from at least two individuals.[18] The 53 cm (21 in) long humerus was built likeCetiosauriscus stewarti (C. leedsi of von Huene's 1927 usage), and the two species were originally distinguished fromCetiosaurus by having shorter dorsal vertebrae, a shorter forelimb, and a longer lower leg.[19] Similarities such as the anatomy of the caudal vertebrae were suggested by Christian Meyer and Basil Thüring in 2003 to support the referral ofgreppini toCetiosauriscus.[18] However, Weishampel et al. (2004) and Whitlock (2011) considered"Cetiosauriscus" greppini to beEusauropodaincertae sedis, while Hofer (2005) and Schwarz et al. (2007) concluded that"Cetiosauriscus" greppini represents an unnamed genus of basal eusauropod.[15][20][21][22]"Ornithopsis" greppini was finally named as the new genusAmanzia in 2020.[23]
The speciesCetiosaurus longus, named in 1842 by Owen, was referred to the genusCetiosauriscus without comment by sauropod palaeontologist John Stanton McIntosh in 1990.[24] The species was named for a dorsal and caudal vertebrae from thePortland stone ofGarsington,Oxfordshire (both now missing) and two other caudal vertebrae from the same deposit of nearbyThame. Owen also referred a single vertebra and somemetatarsals originally namedCetiosaurus epioolithicus (an invalidnomen nudum) to the species. One of the vertebrae (OUMNH J13871) may instead be acervical, as it has one mildly convex and one concave articular face. Characterised as having uniquely elongate vertebralcentra (body of the vertebra),C. longus is not adiagnostic taxon. As it lacks any diagnostic features ofCetiosauriscus, the species should be referred to by its original designation,Cetiosaurus longus.[4]
Cetiosaurus glymptonensis, named on the basis of nine middle-distal caudal centra from theForest Marble Formation of Oxfordshire, England, was referred toCetiosauriscus by McIntosh in 1990. These caudal vertebrae were considered to be more elongate than those ofCetiosaurus oxoniensis, but caudal length proportions vary significantly throughout the tail and in different taxa,Apatosaurus,Diplodocus andCetiosauriscus having similarly elongate caudal vertebrae.[4] The more anterior caudals have a large ridge two-thirds up the centrum and a smaller ridge one-third up. These ridges are similar to the middle caudals ofCetiosauriscus. Still, they are absent in caudals of the same size and proportions, and because of this difference the species was concluded to be separate fromCetiosauriscus by Upchurch and Martin in 2003.[4] "Cetiosaurus"glymptonensis is considered to be Eusauropodaincertae sedis by Upchurch and Martin (2003), Weishampel and colleagues (2004) and Whitlock (2011), and is in need of a new genus name because it has a single diagnostic feature, the lateral ridges.[4][15][20]
In1980, Charig described a specimen of indeterminate diplodocid from the Early Cretaceous of England, and re-examined the holotype ofCetiosauriscus leedsii to compare its characteristics. In this publication he confirmed that the ilium of the holotype ofC. leedsii, NHMUK PV R1988, was too incomplete to be compared to the also incomplete ilium of the referred specimen NHMUK PV R3078. Because of the lack of overlap the referral of NHMUK PV R3078 toCetiosauriscus leedsii was no longer verifiable, so Charig named the new speciesCetiosauriscus stewarti for NHMUK PV R3078. The specific name was chosen to honour Sir Ronald Stewart, the chairman of the London Brick Company that owned the clay pit the fossils had been found in. Furthermore, Charig consideredCetiosauriscus leedsii andCetiosauriscus greppini to bedubious taxa, makingC. stewarti the only valid species withinCetiosauriscus.[1] Because of the invalidity of the type speciesC. leedsii, Charig made a petition to theInternational Code of Zoological Nomenclature (ICZN) in1993 to designateCetiosauriscus stewarti as the type species of its genus, being the taxon containing the specimen Huene had originally named the genus for and distinguished fromCetiosaurus, and also a taxonomically more stable name.[14] This was accepted by the ICZN in1995, makingCetiosauriscus stewarti the type species ofCetiosauriscus.[25] The only specimen that can confidently be assigned toC. stewarti is the holotype NHMUK PV R3078, although it is possible that isolated teeth from the Oxford Clay could be from the taxon.[7][17]
Cetiosauriscus was a moderately sized, quadrupedal eusauropod. It had a moderately long tail, and relatively long arms making the shoulders level with the hips.Cetiosauriscus was approximately 15 m (49 ft) long based on the known skeleton, comparable to possible relatives like 16 m (52 ft) longCetiosaurus, and 16.5 m (54 ft) longPatagosaurus.[26] The weight ofCetiosauriscus is less certain, depending on its phylogenetic placement. Restored as a diplodocid,Cetiosauriscus was estimated by Paul (2010[27]) as 4 t (3.9 long tons; 4.4 short tons), but restored as a cetiosaur it was estimated by Paul (2016[26]) as 10 t (9.8 long tons; 11 short tons).[26][27]
The dorsal vertebrae of NHMUK PV R3078 are incomplete or fragmentary. A partial anterior dorsal is known from a single centrum, which is about as long as wide, with a strong anterior articular ball (anopisthocoelous condition).[10] On thelateral surfaces (sides) of the centrum there are deep but smallpleurocoels (depressions in the sides of vertebrae forair sacs).[2][15] A single middle dorsal centrum is preserved, slightly smaller than the anterior dorsal. The pleurocoel is more elongate, but like the anterior dorsal there is noventral (underside) concavity. A posterior dorsal is also known and is probably the last dorsal before the sacrum (vertebrae between the pelves). It preserves the entire centrum and most of the neural arch, and is significantly shortened in length compared to the other dorsals, although it is about as wide across as tall. A shallow pleurocoel is also present, but is placed higher on the side of the centrum and disappears into theneural arch. Unlike the anterior dorsal, the posterior dorsal is only very slightly opisthocoelous. A tall and narrowhyposphene (thin vertical ridge below the anterior processes of the arch, providing additional vertebral articulation[15]) is present and well expanded off the arch. A single dorsalneural spine is also preserved. It is flattened and not tall, with a narrowed tip, and the only noticeable laminae present are the spinopostzygapophyseal laminae running down the rear corners of the spine to thepostzygapophyses.[10] This is unlike most diplodocoids where there are many laminar running along the length of the spines.[28] Four neural spines of the sacrum are preserved, three of which form a single plate and the fourth of which is separate, like inDiplodocus.[10][2]
Of the anterior four caudal vertebrae, the anteriormost two are highly incomplete. Both the short, but wider-than-tall, centra preserve traces of the sideways projections (transverse processes) found in other vertebrae, which are very low on the sides compared to following caudals. The neural spines are very thin, thinning to a single ridge in front (the prespinal lamina), but having two spinopostzygapophyseal laminae like the dorsals. The fourth caudal is the most complete anterior caudal. The centrum is concave in front, but flat behind (amphiplatyan). There are no pleurocoels unlike the dorsals, and the transverse processes begin in the top half of the centrum. The centrum is 10 cm (3.9 in) long, 27 cm (11 in) tall and 28 cm (11 in) wide, with the total vertebra being 66 cm (26 in) tall. Anterior caudals of theCetiosaurus leedsi specimen NHMUK PV R1984 are very similar to those ofCetiosauriscus, but the neural arches are not as tall inC. leedsi, and the transverse processes lack a prominent ridge along the top of them. Middle and posterior caudals from a nearly continuous series of 27 bones are well preserved inCetiosauriscus. The later vertebrae are slightly more elongate than those in front, and slightly less concave in their anterior face. Moving towards the end of the tail the centra reduce in size and the transverse processes shrink until they are completely absent, with the neural spines becoming shorter, thinner, and more slanted. The seventh vertebrae of the series, at 45 cm (18 in) tall, is 18 cm (7.1 in) long, only one cm longer than the 21st of the same series that is 22.5 cm (8.9 in) tall.[10] A distinguishing characteristic ofCetiosauriscus is the presence of a front-to-back concavity on the top of the anterior and middle caudal neural spines.[15]
Cetiosauriscus preserves a single right scapula (shoulder blade), which is elongate and slender. The scapula is 96.5 cm (38.0 in) long and 17.5 cm (6.9 in) wide at the middle, making it very narrow.[10][29] The inner face is flat across, while the outer face is gently convex. There is no expansion of the far end of the blade. The bone thickens close to the humerus joint, where it also articulates with the coracoid. The coracoid is incomplete, but enough is preserved to show it is rectangular, and longer, at 35 cm (14 in), than it is wide—38 cm (15 in). A 94 cm (37 in) long humerus is known, and complete with minimal crushing. The bone is short and stout, with a robustcrest for the deltoid muscle along the upper half of the bone.[10] The shape of the humerus is similar to the shortness ofNeuquensaurus, although overall the forelimb is long, as inDiplodocus andCetiosaurus, being 69% of the femur length.[29][15] The distal end isroughened for a largecartilage cap as found in some other eusauropods like "Cetiosauriscus"greppini.[18] The radius and ulna are broken, but complete they would have been 76 cm (30 in) long.[10]
The hindlimb ofCetiosauriscus is about3⁄2 the length of the forelimb. Both ilia are very fragmentary, but the two sides supplement each other to give a reasonable idea of the proportions of the complete bone. The ilium is 1.02 m (3.3 ft) long, and has a long and slender pubicpeduncle.[10] It is proportionally lower than inCetiosaurus, being similar in proportions toHaplocanthosaurus and the later "Titanosauridae".[2][29] The left femur is complete, but part of the shaft is eroded away. It is very slender, being 1.36 m (4.5 ft) tall but only 19.5 cm (7.7 in) wide at the middle.[10] This verygracile femoral morphology is shared withAmphicoelias,Shunosaurus,Ligabuesaurus and a specimen ofDiplodocus, being more gracile thanCetiosaurus and most other eusauropods.[2][28] A prominent fourth trochanter is present, but the remaining shaft is very compressed. The tibia, fibula and pes are also preserved, but are fragmentary and disarticulated making comparisons difficult, the lower hindlimb being about 80 cm (31 in) upright.[10][29] The foot is similar toDiplodocus andBrontosaurus, where the first toes are large and clawed, and the outer ones are small and clawless. Metatarsal III is the longest, followed by metatarsal IV, II, V and I. Metatarsal I is the widest, and the width of the bones decreases numerically.[10]
Cetiosauriscus was originally classified by Huene as a genus in thefamilyCetiosauridae, within thesubfamilyCardiodontidae. The subfamily, including the other taxaCetiosaurus,Haplocanthosaurus,Dystrophaeus,Elosaurus andRhoetosaurus, was founded upon the generalbasal features of elongate cervicals and shortened dorsals—both opisthocoelous,amphicoelous caudals that are rod-shaped distally, pairedsternal plates, an ilium lacking the postacetabular process (region of the ilium behind the ischium joint andacetabulum), a very widepubis, wide distal ischium, significantly shorter forelimb than hindlimb, fibula lacking the middle muscle attachment, and longmetacarpals and shortmetatarsals.[2] This classification was amended in 1932 when Huene concludedCetiosauriscus was closer toHaplocanthosaurus thanCetiosaurus in the family, because of forelimb and hindlimb proportions.[29] Conversely, in1956,Alfred Romer synonymisedCetiosauriscus andCetiosaurus, a position that has not been followed by subsequent studies on the taxon.[1][30]
David S. Berman and McIntosh in1978 referredCetiosauriscus to the familyDiplodocidae along with multiple other genera;Diplodocus,Apatosaurus,Barosaurus,MamenchisaurusDicraeosaurus andNemegtosaurus. Like other members of the family,Cetiosauriscus possesses wing-like transverse processes, divided chevrons with forward and backward projections, the tail is "whiplash"-like, the humerus is 2/3 the length of the femur, thecalcaneum is absent, metatarsal III and IV are the longest, and metatarsal I has a process on the bottom back corner.[31] This referral would makeCetiosauriscus, known from the Callovian, the oldest diplodocid, millions of years older thanDiplodocus,Barosaurus orApatosaurus. In the paper namingCetiosauriscus stewarti, Charig also described the chevrons of a new specimen and created the term "diplodociform" to describe them. This meant they were robust and double-beamed, as inDiplodocus and its relatives likeMamenchisaurus. Because of the similarly "diplodociform" chevrons, Charig referredCetiosauriscus to the Diplodocidae along with the new specimen.[1] Elaborating upon his earlier paper, McIntosh (1990[24]) weakly referredCetiosauriscus to the subfamilyDiplodocinae, characterised by more cervicals and fewer dorsals, tall sacrum neural spines, short forelimbs, no calcaneum, metatarsals III and IV being the longest, and a small process on the distal end of metatarsal I. The subfamily also includedDiplodocus,Barosaurus andApatosaurus.[24] In2004 this placement was followed by Weishampelet al. without comment.[15]
Aphylogenetic analysis ofCetiosauriscus was conducted in 2003 by Julia Heathcote and Upchurch, based upon the two most inclusive matrices of the time, those ofJeffrey A. Wilson (2002[32]) and Upchurch (1995[33]), neither of which had included the taxon in the past. Added to the analysis of Upchurch,Cetiosauriscus placed as the sister taxon ofTehuelchesaurus, in a group includingMamenchisaurus,Omeisaurus andEuhelopus, and a placement within a group ofOmeisaurus andMamenchisaurus was also found by using the Wilson matrix. Based on these two results, Heathcote and Upchurch concludedCetiosauriscus was not a diplodocid or even withinDiplodocoidea, instead being a more basal sauropod outsideNeosauropoda.[13] The phylogenetic analysis of Rauhutet al. (2005[34]) resolvedCetiosauriscus in a clade withOmeisaurus, itself in a group withLosillasaurus andMamenchisaurus, outside of Neosauropoda.[34] The phylogenetic relationships ofCetiosauriscus were also tested in2015 by Tschoppet al., as a potential diplodocid. Although the genus was found to be withinDiplodocimorpha with one analysis method, it was also found outside Neosauropoda. In both,Cetiosauriscus stewarti was found to be in a clade alone withBarosaurus affinis, a dubious species known only from foot bones. Tschoppet al. concluded thatCetiosauriscus was not a diplodocid or a diplodocoid, as forcing it to be outside Neosauropoda was moreparsimonious than forcing it to be within Diplodocoidea in all analyses. As the paper was only to test relationships within Diplodocidae, more solid conclusions regarding the position ofCetiosauriscus could not be made. The results of the favouredcladogram of Tschoppet al. is shown below:[28]
The series of distal caudal vertebrae NHMUK PV R1967, once referred toCetiosauriscus, is similar to the caudals ofDiplodocus, with two convex ends (biconvex) and a long and thin centrum. These caudals display signs of injury at two points along the series of ten vertebrae, where there are signs of breakage that was later healed.[10] These lesions were identified as the same form of pathologies as found on the tail ofDiplodocus.[35] It has been suggested that the biconvex distal caudal vertebrae in sauropods were used for making whip-like cracking noise, being thin and delicate and not intended for impact, as the joints would be very vulnerable to damage rendering them useless.[36]
Cetiosauriscus lived during the Callovian, anepoch in the Middle Jurassic, about 166 to 164 mya.[37]The single specimen is known from the Lower Member of the Oxford Clay Formation, along with multiple other dinosaur genera and many other groups of animals, in thebiozone of theindex fossilKosmoceras jason.[7][17] The Oxford Clay Formation is a marine deposit of southern and middle England, known for the high-quality preservation of some fossils and the large diversity of taxa.[17] Sediments are generally brownish-greymudstone, organic-rich with plentiful crushedammonites andbivalves, at most 65 m (213 ft) thick.[38] A large diversity offlora can be seen, preserved in the form of pollen and spores.Gymnosperms are present, along withpteridophytes, unidentifiable wood fragments, other intermediate pollen, and miscellaneous organic plant material.[39]
The intermediate sauropodOrnithopsis leedsi is known from the same section of the formation asCetiosauriscus, along with thestegosauridsLexovisaurus durobrivensis andLoricatosaurus priscus (which are possibly synonyms), the basalankylosaurSarcolestes leedsi, theornithopodCallovosaurus leedsi, and a second unnamed ornithopod taxon. Dinosaur eggs that have not yet been assigned to a taxon are also known from the Lower Oxford Clay. ThetheropodsEustreptospondylus and possiblyMegalosaurus are also known from the Oxford Clay Formation, but slightly younger deposits (the Middle Member).[15] In addition, the theropodMetriacanthosaurus is from an unknown level and age in the formation.[17]
Hundreds ofinvertebrates are known from the marine deposits, including bivalves,gastropods,scaphopods, ammonites,teuthoids, anautiloid,foraminifera,coelenterates,bryozoans,brachiopods,annelids,crustaceans,ostracods,cirripedes andechinoderms. Fish are known from the cladesElasmobranchii,Chimaera, andActinopterygii, and theichthyosaurOphthalmosaurus, theplesiosaursCryptoclidus,Muraenosaurus,Tricleidus,Liopleurodon,Peloneustes,Pliosaurus andSimolestes, thecrocodiliansMetriorhynchus andSteneosaurus, and thepterosaurRhamphorhynchus were all present.[17]
{{cite book}}:ISBN / Date incompatibility (help)
