Homoeosaurus

Homoeosaurus Temporal range: 150–140  Ma PreꞒ Ꞓ O S D C P T J K Pg N Late Jurassic - Early Cretaceous
Homoeosaurus maximiliani
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Rhynchocephalia
Suborder:	Sphenodontia
Infraorder:	Eusphenodontia
Clade:	Neosphenodontia
Genus:	† Homoeosaurus von Meyer, 1847
Type species
†H. maximiliani von Meyer, 1847
Other species
†H. majorBoulenger, 1891 †H. parvipesCocude-Michel, 1963 †H. solnhofensisCocude-Michel, 1963

Homoeosaurus is an extinct genus of rhynchocephalian reptile, known from the Late Jurassic-earliest Cretaceous of Europe, with specimens being reported from France (Canjuers Lagerstatte), England (Purbeck Group) and Germany (Solnhofen Limestone). Several species have been described within the genus, based on varying proportions of the limb bones to the body length based on the presacral vertebrae. Specimen C.M.6438 of H. maximiliani from Germany has a total length of around 17 centimetres (6.7 in), with a skull length of about 1.7 centimetres (0.67 in). In comparison to other rhynchocephalians, the limbs are proportionally long. ^[1] Recent studies have classified Homoeosaurus as a member of Neosphenodontia, with some studies including it as part of the clade Leptorhynchia, also including sapheosaurs, pleurosaurs, Kallimodon and Vadasaurus. ^[2] Despite being found in aquatic deposits, it is suggested to have been terrestrial. ^[3] Analysis of its limb bone morphology suggests that it was probably capable of climbing and may have climbed trees and/or rocky surfaces at least some of the time. ^[4] It is thought to have been a carnivore/insectivore. ^[5] One specimen was found as stomach contents of the fish Belonostomus. ^[6]

Cladogram after Beccari et al. 2025: ^[4]

Rhynchocephalia

† Gephyrosaurus Sphenodontia † Diphydontosaurus † Planocephalosaurus Eusphenodontia † Clevosaurus (paraphyletic) Neosphenodontia Sphenodontidae †Eilenodontinae † Priosphenodon † Sphenotitan Sphenodontinae † Opisthiamimus † Navajosphenodon † Sphenofontis Sphenodon (tuatara) †Homoeosaurus solnhofensis †Homoeosaurus maximiliani †Homoeosaurus parvipes † Sphenodraco † Kallimodon †Pleurosauridae † Derasmosaurus † Ankylosphenodon † Palaeopleurosaurus † Arcosaurus † Pleurosaurus † Vadasaurus †Sapheosauridae † Sapheosaurus † Piocormus † Oenosaurus

References

• Paleontology portal

1. Wu X-C. The comparative anatomy and systematics of Mesozoic sphenodontians. Ph.D. Thesis, McGill University. 1991. p. 84-113.
2. DeMar, David G.; Jones, Marc E. H.; Carrano, Matthew T. (2022-12-31). "A nearly complete skeleton of a new eusphenodontian from the Upper Jurassic Morrison Formation, Wyoming, USA, provides insight into the evolution and diversity of Rhynchocephalia (Reptilia: Lepidosauria)". Journal of Systematic Palaeontology. 20 (1): 1–64. doi:10.1080/14772019.2022.2093139. hdl: 2440/136608 . ISSN   1477-2019. S2CID   252325953.
3. Reynoso, Víctor-Hugo (2005-09-30). "Possible evidence of a venom apparatus in a Middle Jurassic Sphenodontian from the Huizachal red beds of Tamaulipas, México" . Journal of Vertebrate Paleontology. 25 (3): 646–654. doi:10.1671/0272-4634(2005)025[0646:PEOAVA]2.0.CO;2. ISSN   0272-4634. S2CID   131602253.
4. Beccari, Victor; Guillaume, Alexandre R. D.; Jones, Marc E. H.; Villa, Andrea; Cooper, Natalie; Regnault, Sophie; Rauhut, Oliver W. M. (2025-07-01). "An arboreal rhynchocephalian from the Late Jurassic of Germany, and the importance of the appendicular skeleton for ecomorphology in lepidosaurs". Zoological Journal of the Linnean Society . 204 (3): zlaf073. doi: 10.1093/zoolinnean/zlaf073 . ISSN   0024-4082.
5. Rauhut, Oliver W. M.; Heyng, Alexander M.; López-Arbarello, Adriana; Hecker, Andreas (2012-10-31). Farke, Andrew A. (ed.). "A New Rhynchocephalian from the Late Jurassic of Germany with a Dentition That Is Unique amongst Tetrapods". PLOS ONE. 7 (10): e46839. Bibcode:2012PLoSO...746839R. doi: 10.1371/journal.pone.0046839 . ISSN   1932-6203. PMC   3485277 . PMID   23118861.
6. Frey, Eberhard; Tischlinger, Helmut (2012-03-07). Fenton, Brock (ed.). "The Late Jurassic Pterosaur Rhamphorhynchus, a Frequent Victim of the Ganoid Fish Aspidorhynchus?". PLOS ONE. 7 (3): e31945. Bibcode:2012PLoSO...731945F. doi: 10.1371/journal.pone.0031945 . ISSN   1932-6203. PMC   3296705 . PMID   22412850.