Prosauropoda

Galton, Peter M.; Upchurch, Paul

doi:10.1525/california/9780520242098.003.0014

Cited by 141 publications

(227 citation statements)

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“…It is not uncommon for late Norian and Rhaetian formations from these continents to contain 3-6 penecontemporaneous sauropodomorph taxa (e.g., Los Colorados Formation: Galton and Upchurch, 2004). In contrast, no unquestionable sauropodomorph remains are known from North America until the Early Jurassic .…”

Section: Late Triassic Sauropodomorphs -Fossil Record and Distributionmentioning

confidence: 99%

“…Unfortunately, the specific interrelationships of these taxa are still controversial, and two main competing phylogenetic hypotheses have been proposed. The first hypothesis suggests that most or all basal sauropodomorphs (i.e., non-sauropod sauropodomorphs) form a monophyletic group that is the sister taxon to Sauropoda (e.g., Sereno, 1999;Benton et al, 2000;Yates and Kitching, 2003;Galton and Upchurch, 2004;Sereno, 2007b;Upchurch et al, 2007a). In contrast, other studies find these taxa as a largely paraphyletic grade where some basal sauropodomorphs are closer to sauropods than they are to each other (e.g., Yates, 2003aYates, ,b, 2007aSmith and Pol, 2007;Yates et al, 2010).…”

Section: Late Triassic Sauropodomorphs -Fossil Record and Distributionmentioning

confidence: 99%

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The origin and early radiation of dinosaurs

Brusatte

Nesbitt

Irmis

et al. 2010

Earth-Science Reviews

242

214

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Dinosaurs were remarkably successful during the Mesozoic and one subgroup, birds, remain an important component of modern ecosystems. Although the extinction of non-avian dinosaurs at the end of the Cretaceous has been the subject of intense debate, comparatively little attention has been given to the origin and early evolution of dinosaurs during the Late Triassic and Early Jurassic, one of the most important evolutionary radiations in earth history. Our understanding of this keystone event has dramatically changed over the past 25 years, thanks to an influx of new fossil discoveries, reinterpretations of long-ignored specimens, and quantitative macroevolutionary analyses that synthesize anatomical and geological data. Here we provide an overview of the first 50 million years of dinosaur history, with a focus on the large-scale patterns that characterize the ascent of dinosaurs from a small, almost marginal group of reptiles in the Late Triassic to the preeminent terrestrial vertebrates of the Jurassic and Cretaceous. We provide both a biological and geological background for early dinosaur history. Dinosaurs are deeply nested among the archosaurian reptiles, diagnosed by only a small number of characters, and are subdivided into a number of major lineages. The first unequivocal dinosaurs are known from the late Carnian of South America, but the presence of their sister group in the Middle Triassic implies that dinosaurs possibly originated much earlier. The three major dinosaur lineages, theropods, sauropodomorphs, and ornithischians, are all known from the Triassic, when continents were joined into the supercontinent Pangaea and global climates were hot and arid. Although many researchers have long suggested that dinosaurs outcompeted other reptile groups during the Triassic, we argue that the ascent of dinosaurs was more of a matter of contingency and opportunism. Dinosaurs were overshadowed in most Late Triassic ecosystems by crocodile-line archosaurs and showed no signs of outcompeting their rivals. Instead, the rise of dinosaurs was a two-stage process, as dinosaurs expanded in taxonomic diversity, morphological disparity, and absolute faunal abundance only after the extinction of most crocodile-line reptiles and other groups.

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Section: Late Triassic Sauropodomorphs -Fossil Record and Distributionmentioning

confidence: 99%

Section: Late Triassic Sauropodomorphs -Fossil Record and Distributionmentioning

confidence: 99%

The origin and early radiation of dinosaurs

Brusatte

Nesbitt

Irmis

et al. 2010

Earth-Science Reviews

242

214

View full text Add to dashboard Cite

show abstract

“…This general pattern of postaxial digit reduction (albeit without digit loss) also characterizes Sauropodomorpha (the sister taxon of theropods within Saurischia) and most lineages of ornithischians (see Weishampel et al, 2004) and therefore was likely established before the origin of Dinosauria. For example, Plateosaurus engelhardti, a taxon that contains perhaps the most primitive hand among sauropodomorphs (Galton and Upchurch, 2004), still expresses a diminished postaxial phalangeal formula relative to Alligator mississippiensis (2-3-4-3-2 vs. 2-3-4-5-3) with ungual phalanges (or the distalmost, clawed phalanges) of digits 4 and 5 reduced to vestiges of bone. Thus, the reduction and loss of digit identities IV and V, which characterizes early theropod evolution and arguably produced the tridactyl hand expressed in crown birds, reflects a trend of posterior digit reduction that likely predates the origin of Dinosauria (Sereno, 1997).…”

Section: Developmental Dynamicsmentioning

confidence: 99%

Identity of the avian wing digits: Problems resolved and unsolved

Young

Bever

Wang

et al. 2011

Developmental Dynamics

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Controversy over bird wing digit identity has been a touchstone for various ideas in the phylogeny of birds, homology, and developmental evolution. This review summarizes the past 10 years of progress toward understanding avian digit identity. We conclude that the sum of evidence supports the Frame Shift Hypothesis, indicating that the avian wing digits have changed anatomical location. Briefly, the derivation of birds from theropod dinosaurs and the positional identities of the avian wing digits as 2, 3, and 4 1 are no longer in question. Additionally, increasing evidence indicates that the developmental programs for identity of the wing digits are of digits I, II, and III. Therefore, the attention moves from whether the digit identity frame shift occurred, to what the mechanisms of the frame shift were, and when in evolution it happened. There is considerable uncertainty about these issues and we identify exciting new research directions to resolve them. Developmental Dynamics 240:1042-1053,

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“…Hammer and Hickerson (1996) tentatively referred the fragmentary remains of a basal sauropodomorph from the Hanson Formation to the family Plateosauridae, though this referral was not based on any detailed anatomical features beyond the relative size of the material. As with basal theropod systematics, the taxonomy and phylogenetic relationships of basal sauropodomorph dinosaurs are experiencing considerable revision, with the traditional grouping of basal members within a monophyletic Prosauropoda supported or rejected to varying degrees (Galton and Upchurch, 2004;Yates, 2006Yates, , 2007Smith and Pol, in review; see also contributions in Barrett and Batten, 2007). Our research has revealed that the Antarctic material represents a new taxon, clearly distinguished from Plateosaurus and other basal sauropodomorphs by several autapomorphic features in the metatarsus (Smith and Pol, in review).…”

Section: Phylogenetic Reviewmentioning

confidence: 99%

The dinosaurs of the Early Jurassic Hanson Formation of the Central Transantarctic Mountains: phylogenetic review and synthesis

Smith¹,

Makovicky²,

Hammer³

et al. 2007

Open-File Report

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The Hanson Formation of the Central Transantarctic Mountains has yielded a diverse Early Jurassic terrestrial fauna, which includes the nearly complete theropod dinosaur, Cryolophosaurus ellioti, and a fragmentary basal sauropodomorph dinosaur. The Hanson Formation dinosaurs are important for understanding early dinosaur evolution because: 1) they preserve a mosaic of morphological traits that render them useful for interpreting poorly known parts of the dinosaur evolutionary tree; 2) they are from the Early Jurassic, a critical period in early dinosaur evolution about which knowledge is scant; and 3) they are the only known Early Jurassic dinosaurs from Antarctica, making them particularly valuable for understanding patterns of biotic interchange during this time. Recent research suggests that Cryolophosaurus belongs to a geographically widespread clade of mid-sized, Early Jurassic theropods with cranial crests that includes Dilophosaurus wetherilli, 'Dilophosaurus' sinensis, and Dracovenator, and renders Coelophysoidea sensu lato non-monophyletic. The Antarctic sauropodomorph represents a distinct taxon that is a member of a similarly diverse massospondylid clade. This taxon shares a number of features with more derived sauropodomorphs, and provides additional evidence for the paraphyly of Prosauropoda. The phylogenetic relationships of the Antarctic dinosaurs are also consistent with a pattern of worldwide faunal homogeneity between Early Jurassic continental biotas. Furthermore, these analyses support a "ladder-like" arrangement for basal theropod and basal sauropodomorph phylogeny, suggesting that these groups passed through "coelophysoid" and "prosauropod" stages of morphological organization early in their respective evolutionary histories.

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Prosauropoda

Cited by 141 publications

References 0 publications

The origin and early radiation of dinosaurs

The origin and early radiation of dinosaurs

Identity of the avian wing digits: Problems resolved and unsolved

The dinosaurs of the Early Jurassic Hanson Formation of the Central Transantarctic Mountains: phylogenetic review and synthesis

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