Tail anatomy of the Alvarezsauria (Theropoda, Coelurosauria), and its functional and behavioural implications

Meso, J.G.; Qin, Zichuan; Pittman, Michael; Canale, Juan Ignacio; Salgado, Leonardo; Díaz, Verónica Díez

doi:10.1016/j.cretres.2021.104830

Cited by 10 publications

(8 citation statements)

References 55 publications

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“…As such, Linhenykus had a foot morphology that allowed good stabilisation during such locomotion (Hone et al, 2012). What is more, the tail anatomy was characterised by a particular ability to change rotational inertia (Meso et al, 2021).…”

Section: Discussionmentioning

confidence: 99%

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The forelimbs of Alvarezsauroidea (Dinosauria: Theropoda): Insight from evolutionary teratology

Guinard¹

2022

Journal of Morphology

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Alvarezsauroidea (Tetanurae) are nonavian theropod dinosaurs whose forelimb evolution is characterised by the overdevelopment of digit I, at the expense of the other two digits, complemented by a drastic forelimb shortening in derived species (Parvicursorinae). These variations are recognised as evolutionary developmental anomalies. Evolutionary teratology hence leads to a double diagnosis with (1) macrodactyly of digit I and microdactyly of digits II and III, plus (2) anterior micromelia. The teratological macrodactyly/microdactyly coupling evolved first.Developmental mechanisms disturbing limb proportion are thought to be convergent with those of other Tetanurae (Tyrannosauridae, Carcharodontosauridae). As for the manual anomalies, both are specific to Alvarezsauroidea (macrodactyly/ microdactyly) and inherited (digit loss/reduction). While considering the frame-shift theory, posterior digits develop before the most anterior ones. There would therefore be a decrease in the area devoted to digits II (condensation 3) and III (condensation 4), in connection with the Shh signalling pathway, interacting with other molecular players such as the GLI3 protein and the Hox system. Developmental independence of digit I (condensation 2) would contribute to generating a particular morphology. Macrodactyly would be linked to a variation in Hoxd-13, impacting Gli3 activity, and increasing cell proliferation. The loss/reduction of digital ray/phalanges (digits II and III), would be associated with Shh activity, a mechanism inherited from the theropodan ancestry. The macrodactyly/microdactyly coupling, and then anterior micromelia, fundamentally changed the forelimb mechanical function, compared to the 'classical' grasping structure of basal representatives and other theropods. The distal ossification of the macrodactylian digit has been identified as physiological, implying the use of the structure. However, the debate on a particular 'adaptive' use is pointless as the ecology of an organism is interactively complex, being both at the scale of the individual and dependent on circumstances. Other anatomical features also allow for compensation and different predation (cursorial hindlimbs).

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Section: Discussionmentioning

confidence: 99%

“…What is more, the tail anatomy was characterised by a particular ability to change rotational inertia (Meso et al, 2021).…”

Section: Impact Of Manual Teratologies On Alvarezsauroideamentioning

confidence: 99%

The forelimbs of Alvarezsauroidea (Dinosauria: Theropoda): Insight from evolutionary teratology

Guinard¹

2022

Journal of Morphology

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“…Other muscle reconstructions generally have been carried out for lineages that are more closely related to Aves, with great effort spent on Coelurosauria; for example, the tyrannosauroid Tyrannosaurus (Carrano & Hutchinson, 2002), Ornithomimidae (Russell, 1972), Megaraptoridae (White et al, 2016), unenlagiids (Motta et al, 2018), alvarezsaurids (Meso et al, 2021), and maniraptoran species (Hutchinson et al, 2008;Rhodes et al, 2021;Smith, 2021Smith, , 2023.…”

Section: Why S Tudy Muscul Ature Inmentioning

confidence: 99%

“…Using the EPB, our comparisons mainly were based on Crocodylia and Aves, but not restricted to these groups; Lepidosauria and Testudines were also considered (Bishop et al, 2021;Hutchinson, 2002). The pelvic and thigh musculature of extant taxa was evaluated from the following literature on Crocodylia (e.g., Hattori & Tsuihiji, 2021;Otero et al, 2010;Romer, 1923a;Suzuki et al, 2011;Wilhite, 2023), Avialae (e.g., Clifton et al, 2018;Hattori & Tsuihiji, 2021;Hudson et al, 1959;Meso et al, 2021;Patak & Baldwin, 1998;Picasso, 2010;Romer, 1923c;Rowe, 1986;Suzuki et al, 2014), and other Tetrapoda/Reptilia (e.g., Dick & Clemente, 2016;Gregory & Camp, 1918;Hattori & Tsuihiji, 2021;Romer, 1942). Dissection of one Crocodylus niloticus and one Numida meleagris specimen during this study further enhanced our musculoskeletal comparisons and delineations of the locomotory muscle positioning.…”

Section: Myological Reconstruction Homology and Character Mappingmentioning

confidence: 99%

“…Concerning early tetanuran theropods, the only efforts to date relate to the allosauroids Allosaurus and Acrocanthosaurus , not only on the basis of musculature (e.g., Cau & Serventi, 2017), but also body mass estimation and biomechanical analysis (Bates, Benson, & Falkingham, 2012). Other muscle reconstructions generally have been carried out for lineages that are more closely related to Aves, with great effort spent on Coelurosauria; for example, the tyrannosauroid Tyrannosaurus (Carrano & Hutchinson, 2002), Ornithomimidae (Russell, 1972), Megaraptoridae (White et al., 2016), unenlagiids (Motta et al., 2018), alvarezsaurids (Meso et al., 2021), and maniraptoran species (Hutchinson et al., 2008; Rhodes et al., 2021; Smith, 2021, 2023).…”

Section: Why Study Musculature In Non‐avian Theropods?mentioning

confidence: 99%

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Reconstruction of the pelvic girdle and hindlimb musculature of the early tetanurans Piatnitzkysauridae (Theropoda, Megalosauroidea)

Lacerda,

Bittencourt,

Hutchinson

2023

Journal of Anatomy

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Piatnitzkysauridae were Jurassic theropods that represented the earliest diverging branch of Megalosauroidea, being one of the earliest lineages to have evolved moderate body size. This clade's typical body size and some unusual anatomical features raise questions about locomotor function and specializations to aid in body support; and other palaeobiological issues. Biomechanical models and simulations can illuminate how extinct animals may have moved, but require anatomical data as inputs. With a phylogenetic context, osteological evidence, and neontological data on anatomy, it is possible to infer the musculature of extinct taxa. Here, we reconstructed the hindlimb musculature of Piatnitzkysauridae (Condorraptor, Marshosaurus, and Piatnitzkysaurus). We chose this clade for future usage in biomechanics, for comparisons with myological reconstructions of other theropods, and for the resulting evolutionary implications of our reconstructions; differential preservation affects these inferences, so we discuss these issues as well. We considered 32 muscles in total: for Piatnitzkysaurus, the attachments of 29 muscles could be inferred based on the osteological correlates; meanwhile, in Condorraptor and Marshosaurus, we respectively inferred 21 and 12 muscles. We found great anatomical similarity within Piatnitzkysauridae, but differences such as the origin of M. ambiens and size of M. caudofemoralis brevis are present. Similarities were evident with Aves, such as the division of the M. iliofemoralis externus and M. iliotrochantericus caudalis and a broad depression for the M. gastrocnemius pars medialis origin on the cnemial crest. Nevertheless, we infer plesiomorphic features such as the origins of M. puboischiofemoralis internus 1 around the “cuppedicus” fossa and M. ischiotrochantericus medially on the ischium. As the first attempt to reconstruct muscles in early tetanurans, our study allows a more complete understanding of myological evolution in theropod pelvic appendages.

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

Cerroni,

Otero,

Novas

2024

The Anatomical Record

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

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Tail anatomy of the Alvarezsauria (Theropoda, Coelurosauria), and its functional and behavioural implications

Cited by 10 publications

References 55 publications

The forelimbs of Alvarezsauroidea (Dinosauria: Theropoda): Insight from evolutionary teratology

The forelimbs of Alvarezsauroidea (Dinosauria: Theropoda): Insight from evolutionary teratology

Reconstruction of the pelvic girdle and hindlimb musculature of the early tetanurans Piatnitzkysauridae (Theropoda, Megalosauroidea)

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

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