| Ornithopsis | |
|---|---|
 | |
| Lectotype vertebra NHMUK R 28632 | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Clade: | †Macronaria |
| Clade: | †Titanosauriformes |
| Genus: | †Ornithopsis Seeley,1870[1] |
| Species: | †O. hulkei |
| Binomial name | |
| †Ornithopsis hulkei Seeley, 1870[1] | |
| Synonyms[4] | |
Ornithopsis (meaning "bird-likeness") is a genus ofsauropoddinosaur, from theEarly Cretaceous ofEngland and possiblyGermany. Thetype species, which is the only species seen as valid today, isO. hulkei, which is only known from fragmentary remains.[5]
Gideon Algernon Mantell described many fossils that had been previously collected from theTilgate Forest of theEarly CretaceousWealden Formation in his1833 paper on the geology of southeast England, including a bone he considered to be thequadrate ofIguanodon, otherwise only known definitively from teeth that had been found in the area since1822.[6][7] The bone was redescribed byRichard Owen in1854, who reaffirmed its referral as a quadrate ofIguanodon, but also suggested it could be the same bone ofStreptospondylus orCetiosaurus as it was not directly associated with the characteristic teeth ofIguanodon.[8] This specimen is stored asBritish Museum of Natural History R2239, having been purchased from Mantell in1838.[9]
Specimen NHMUK PV R 28632, a similar bone to NHMUK PV R 2239 was described in1870 byHarry Govier Seeley, found in the deposits on theIsle of Wight and purchased from Mantell by the British Museum in 1853.[9][1] Seeley properly identified the two fossils asvertebrae, and noted that the features considered by Mantell and Owen to indicate thetympanic cavity was in fact openings in the walls of the vertebralcentrum, showing that the bones were invaded by cavities for air sacs as seen in bothpterosaurs and modernbirds. Seeley gave the nameOrnithopsis hulkei for the vertebrae, named in honour of his colleagueJohn Whitaker Hulke, considering the taxon to be between pterosaurs and birds, and possibly allied withdinosaurs.[1] The genus name is derived from Greekὄρνις, "bird" andὄψις, "likeness".[4]
Owen revisited the material in1875, where he described multiple new species within his new genusBothriospondylus. Agreeing with the vertebral identity of NHMUK PV R 2239, but considering it closer to the type speciesBothriospondylus suffossus than any flying animal as Seeley had suggested, Owen gave the new species nameBothriospondylus elongatus for the specimen. For NHMUK PV R 28632, Owen named the new speciesBothriospondylus magnus, as he did not consider the two Wealden vertebrae to belong to the same taxon. Owen heavily disagreed with the interpretations of Seeley that the vertebrae were open and lightly constructed and showed relationships to birds and pterosaurs, considering the nameOrnithopsis to be glaringly false and thus suggesting his new names should have priority over Seeley's older designations.[2] Owen then reassignedB. magnus to the genusChondrosteosaurus asChondrosteosaurus magnus in1876, considering it closely related to the type speciesChondrosteosaurus gigas from the Wealden.[3]
Hulke described additional sauropod material from the Wealden in1879, and reevaluated the designations used by Owen and Seeley. Hulke identified NHMUK PV R 28632 as the type ofO. hulkei, renderingBothriospondylus magnus andChondrosteosaurus magnus as junior objective synonyms. As well, Hulke noted that the comment of Owen that the nameOrnithopsis was misleading was false, as the vertebrae were lightly-constructed regardless of their relationships. Hulke also referred the genusEucamerotus, named earlier by him in 1870, and the genusChondrosteosaurus toOrnithopsis as junior synonyms, with other fossils found in the Wealden beds showing that they all shared the unique internal structure ofOrnithopsis.[4] Though William Blows identified in1995 that most of the Wealden sauropod material has been designated as dubious or intermediate, the type vertebra ofOrnithopsis shows unique features in its lateral compression and a ventral ridge, and represents a diagnostic titanosauriform.[10][5]
In 2023, a fragmentary dorsal vertebra from theBalve in northwestern Germany, preserved in limestone dating to the LateBarremian-EarlyAptian, was described. It was referred toOrnithopsis sp.? because it also possesses the lateral compression considered unique toOrnithopsis. However, the poor preservation of the specimen makes the referral tentative.[11]
Hulke described pelvis material, NHMUK PV R 97, from the Wealden in1882, found associated with a few vertebrae, as the new speciesOrnithopsis eucamerotus. He retainedEucamerotus andChondrosteosaurus as synonyms ofOrnithopsis, but suggested thatO. hulkei should only contain the original vertebra NHMUK PV R 2239.[12][9] The designation by Hulke of NHMUK PV R 2239 as type conflicted with his earlier assertion that NHMUK PV R 28632 was the type, so Lydekker corrected this in1888 by formally designated NHMUK PV R 28632 as the only type with the consultation of Seeley.[9]
Hulke described more material asOrnithopsis in 1887, for some vertebrae, ribs, a pelvis, and fragments collected in the Eyesbury Jurassic deposits ofNorthamptonshire byAlfred Nicholson Leeds. The vertebrae and pelvis showed many similarities with the specimens ofOrnithopsis from theWealden Group, but the much larger size of the Eyesbury specimens, their robusticity, and their older age were considered sufficient to describe as a new species, which Hulke namedOrnithopsis leedsii after the discoverer Alfred Leeds. Hulke placed the genus within the sauropod familyAtlantosauridae, suggesting a close relationship withCetiosaurus oxoniensis.[13] The specimens named asOrnithopsis leedsii are stored as specimens NHMUK PV R 1985-1988, having been collected in May of 1892, and possibly being the first sauropod collected by Leeds and his brothers. Unlike the other specimens,O. leedsii came from the lowerCallovian deposits of theKellaways Formation below theOxford Clay where most specimens were derived from.[14]
Hulke described ahumerus found in 1868 by J.C. Mansel in theKimmeridge Clay in1869, considering it a large saurian possibly related toCetiosaurus orPelorosaurus.[15] He then gave it the nameIschyrosaurus in1874, reiterating its close relationship toCetiosaurus oxoniensis,Cetiosaurus humerocristatus, andGigantosaurus.[16] Though it was not given a species name at the time,Richard Lydekker identified it as the speciesOrnithopsis manseli in1887 based on an unpublished manuscript name provided by Hulke, as well as describing additional Wealden material asO. hulkei, and suggestingCetiosaurus humerocristatus was a synonym ofO. leedsii.[17]Cetiosaurus oxoniensis was reassigned toOrnithopsis asO. oxoniensis in 1888 byHarry Govier Seeley, a proposal that was not endorsed at the time by Lydekker,[18] who also suggested thatO. leedsii andO. humerocristatus were possibly distinct based on a difference in age, but thatChondrosteosaurus andOrnithopsis eucamerotus were synonyms ofO. hulkei.[9]Ornithopsis leedsii was referred to as the speciesPelorosaurus leedsi by Lydekker in1895,[19] and as the taxonCetiosaurus leedsi byArthur Smith Woodward in the1905,[20] which are incorrect spellings of the species name.[14]
Cetiosaurus leedsii (spelled as "leedsi") had additional remains referred to it by Woodward in 1905, including the anterior caudal vertebrae NHMUK PV R 1984, the distal caudals NHMUK PV R 1967, and the posterior skeleton NHMUK PV R 3078, which preserved most of the arm, leg, pelvis, and vertebrae behind the shoulders. The species was assigned toCetiosaurus as the vertebrae were differently textured, so Woodward considered an assignment toCetiosaurus more proper.[20]Friedrich von Huene did not think the referral of the species toCetiosaurus should be supported, and referred to the taxon as "Cetiosaurus"leedsi. Huene also described the speciesOrnithopsis (?)greppini in the same study in1921, for a long-tailed cetiosaurid from Jurassic deposits aroundBern,Switzerland.[21] Huene retainedO. greppini in the genus in an early1927 review of sauropods, considering the genus to contain the speciesOrnithopsis hulkei,O. leedsii,O. humerocristatus,O. manseli, andO. (?)greppini, with the genus representing taxon withinCetiosauridae alongsideCetiosaurus,Bothriospondylus,Pelorosaurus,Dinodocus, and possiblyRhoetosaurus and "Morosaurus"brevis.[22] Later in the same year, Huene revised his classification, naming the new genusCetiosauriscus forO. leedsii as described by Woodward, andO. (?)greppini.[23]
As the holotype material ofOrnithopsis/Cetiosauriscus leedsii was not considered diagnostic, the more complete specimen NHMUK PV R 3078 was referred to the new taxonCetiosauriscus stewarti, which was then designated as the type species ofCetiosauriscus as it contained the material Huene had originally named the new genus for.[24][25][26][27]Cetiosaurus leedsi was then assigned to an intermediate member ofBrachiosauridae,[28] considered to be a proper species ofOrnithopsis,[14] or an improper species ofOrnithopsis that is an indeterminateeusauropod.[29]Ornithopsis greppini was given the new genus nameAmanzia in a2020 redescription of the original material.[27]
AsIschyrosaurus was used earlier byEdward Drinker Cope for the non-mammalian genusIschyrotherium in1869, the name "Ischyrosaurus" cannot be used forI. manseli, and so the species was retained asOrnithopsis manseli by David Martill and colleagues in2006.[30] The species has also been considered asPelorosaurus manseli.[31][32][33] Upchurchet al., in their review of sauropods (2004), listed it as a dubious sauropod.[34] A 2010 overview of Late Jurassic sauropods from Dorset noted thatO. manseli shared features seen in bothRebbachisauridae andTitanosauriformes, but lacked features to nail down its exact phylogenetic position.[35]
TheOrnithopsis hulkei holotype is basically a centrum lacking the neural spine. The vertebra is heavily pneumatised, filled with large cavities, camellae. It is narrow, tall, has a ridge on the underside, isopisthocoelous and has a posteriorly placed deep subtriangularpleurocoel over two thirds of its length. These features are compatible with a placement within theTitanosauriformes.[5]
Based on comparison withGiraffatitan, the holotype specimen is estimated to be 16–18 m (52–59 ft) in length, with the possible German specimen belonging to a slightly smaller individual.[11]
