Cursorial ecomorphology and temporal patterns in theropod dinosaur evolution during the mid-Cretaceous

Royal Society Open Science, Journal Year: 2025, Volume and Issue: 12(1)

Published: Jan. 1, 2025

Coelurosauria, including modern birds, represents a successful group of theropod dinosaurs that established high taxonomic diversity and significant morphological modifications. In the evolutionary history this group, specialized foot morphology, arctometatarsus, evolved independently in several lineages has been considered an adaptation for cursoriality. While its functional significance extensively studied, temporal pattern parallel evolution, as well origin influencing factors, remains largely unresolved. Here, we show evolution cursorial traits, arctometatarsus hind limb proportions. Our study reveals proportional elongation distal segments preceded ornithomimosaurs oviraptorosaurs. contrast, tyrannosauroids, alvarezsaurs troodontids, tibia metatarsals occurred with acquisition arctometatarsus. The further highlights presence phylogenetic constraint outside specialization is restricted to members group. Finally, our date estimation, based on compiled patterns, demonstrates these traits emerged during mid-Cretaceous (93–120 Ma), suggesting selection locomotor performance throughout interval.

Language: Английский

Appendicular myology of Skorpiovenator bustingorryi: A first attempt to reconstruct pelvic and hindlimb musculature in an abelisaurid theropod

The Anatomical Record, Journal Year: 2024, Volume and Issue: unknown

Published: July 11, 2024

Abstract We present the pelvic and hindlimb musculature of abelisaurid Skorpiovenator bustingorryi , constituting most comprehensive muscle reconstruction to date in ceratosaur theropods. Using extant phylogenetic bracket method, we reconstructed 39 muscles that can commonly found archosaurs. Through identification bone correlates, recognized thigh including knee extensors, m. iliofibularis flexor tibialis externus mm. caudofemorales puboischiofemorales crus important foot extension flexion (e.g., anterior gastrocnemii ). Also, autopodial intrinsic were whose function involve ( extensor digiti 2–4 ), digitorum brevis superficialis interdigital adduction interosseus dorsalis ) abduction interosseous plantaris abductor 4 Abelisaurids like show a deep pre‐ postacetabular blade ilia enlarged cnemial crests, which would have helped increasing moment arm related hip extension. pedal pronation probably but reduced pronator profundus Despite some gross differences morphology outgroups crocodilian metatarsus avian tarsometatarsus), study allows us hypothesize several . These not be arranged tendinous bundles as Neornithes, rather condition similar crocodilians with layers formed by fleshy bellies on plantar dorsal aspects metatarsus. The is key for future studies concerning biomechanics, integration functional ichnological data.

Language: Английский

Chimerism in specimens referred to Saurophaganax maximus reveals a new species of Allosaurus (Dinosauria, Theropoda)

Vertebrate Anatomy Morphology Palaeontology, Journal Year: 2024, Volume and Issue: 12

Published: Dec. 21, 2024

Saurophaganax maximus is the designation of a massive theropod dinosaur recovered from Kenton Member Upper Jurassic Morrison Formation in Oklahoma. The was originally given name Saurophagus but later revised to as former did not conform ICZN standards. Several autapomorphies were described for S. including postorbital lacking boss, atlas vertebra facets proatlas, cervical vertebrae with nearly vertical postzygapophyses, unique accessory laminae on holotype neural arch, pneumatized post-pectoral dorsal centra, laterally bowed femora, tibiae without an astragalar buttress and more prominent distomedial crest, less distally divergent fourth metatarsals, craniocaudally expanded chevrons. However, our re-evaluation these specimens shows that some this material, holotype, parsimoniously referred diplodocid sauropods found same quarry rather than allosaurid. Because saurischian material likely chimeric diagnostic, we propose taxonomic revision hypothesize dual validity. should refer previously undiagnosed diplodocid, instead large 1 Quarry. presence at least one skeletally mature confirmed through paleohistology metatarsal. Despite similarity known species Allosaurus, decisively feature subtle suggest separate species, which describe Allosaurus anax sp. nov.

Language: Английский