Forelimb musculature and osteological correlates in Sauropodomorpha (Dinosauria, Saurischia)

Abstract

This contribution presents the forelimb muscular arrangement of sauropodomorph dinosaurs as inferred by comparisons with living archosaurs (crocodiles and birds) following the Extant Phylogenetic Bracket approach. Forty-one muscles were reconstructed, including lower limb and manus musculature, which prior information available was scarce for sauropodomorphs. A strong emphasis was placed on osteological correlates (such as tubercles, ridges and striae) and comparisons with primitive archosauromorphs are included in order to track these correlates throughout the clade. This should help to elucidate how widespread among other archosaurian groups are these osteological correlates identified in Sauropodomorpha. The ultimate goal of this contribution was to provide an exhaustive guide to muscular identification in fossil archosaurs and to offer solid anatomical bases for future studies based on osteology, myology, functional morphology and systematics.

New Specimen Sheds Light on the Anatomy and Taxonomy of the Early Late Triassic Dinosauriforms from the Chañares Formation, NW Argentina

“…The placement of this muscle sacar approximately matches the area inferred as the insertion of the M . brachialis in other fossil archosaurs (Otero, ). The lateral surface possesses a pair of distally converging, mostly proximodistally oriented low ridges (Fig.…”

“…I: st) and the probable insertion of the M . triceps brachii (Otero, ). A proximodistally extended muscle scar occurs on the lateral surface of the bone, anteroventrally to the lateral tuber (Fig.…”

“…flexor ulnaris posteriorly and the M . pronator quadratus anteriorly (Otero, ). These ridges delimit a flat surface in Lewisuchus admixtus and a broad, shallow longitudinal groove in Asilisaurus kongwe (NMT RB159).…”

“…The placement of this area suggests that it may represent the origin of the Mm . extensores digitorum superficialis (Otero, ). A lateral longitudinal change in slope merges distally with this striated area.…”

Osteological redescription of the Late Triassic sauropodomorph dinosaur Thecodontosaurus antiquus based on new material from Tytherington, southwestern England

“…The scapular lateral fossa is large and shallow, and it is bounded by a low acromial ridge. This fossa represents the scapular origin of M. supracoracoideus (Otero, 2018). The lateral surface of the glenoid lip bears a muscle scar in the form of a rugose oval buttress (Fig.…”