name = Prosauropods
Late Triassic- Early Jurassic
image_width = 250px
image_caption = "
phylum = Chordata
classis = Sauropsida
infraordo = Prosauropoda
infraordo_authority = von Huene, 1920
subdivision_ranks = Families
subdivision = See text
Prosauropoda (pronEng|ˌproʊsɔˈrɒpədə) or prosauropods (IPA|/proʊˈsɔroʊpɒd/) were a group of early
herbivorous dinosaurs that lived during the Triassicand early Jurassicperiods. They were frequently the predominant herbivore in their environment, and quickly reached large size (6 to 10 meters long [20 to 33 ft] ). All prosauropods had a long neck and small head, forelimbs shorter than the hindlimbs, and a very large thumb claw (inherited from the thecodontosaurs) for defense. Most were semi-bipedal, although at least one large form (" Riojasaurus") was fully quadrupedal. They were originally thought to be the ancestors of the sauropods, but are now considered a parallel lineage.
The Prosauropoda were originally defined as the early, bipedal,
Triassicancestors of the great sauropoddinosaurs. More recently, cladistic analysis suggests that rather than being ancestral to sauropods, prosauropods were a sister clade. Recent studies of the genus " Massospondylus" reveal that the Prosauropoda is indeed monophyletic.
The problem however lies in what genera are considered prosauropods. Upchurch (1997) proposes a Node-Based Definition: Blikanasauridae, Thecodontosauridae, Anchisauridae, Plateosauridae, Melanorosauridae, and all
sauropodomorphs closer to them than sauropods. More recently, on the basis of studies of early sauropodomorphs Adam Yatesproposed a cladogram in which the primitive genera "Saturnalia", " Thecodontosaurus", and " Efraasia" (basically, a paraphyletic Thecodontosauridae) represent basal outgroups prior to the prosauropod-sauropod split. " Anchisaurus" (despite its classic "prosauropod" build) is now recognised as the most primitive sauropod (Yates 2004). The melanorosaurs and blikanasaurs are very early members of the sauropod line.
skullwas approximately half the length of the femur; their jawarticulation was slightly below the level of the maxillary toothrow. Their teeth were small, homodont or weakly homodont, spatulate, with coarse marginal serrations; manual digitI bore a twisted first phalanx and an enormous, trenchant ungual medially directed when hyperextended. Prosauropod digits II and III were of subequal length, with small, slightly recurved ungual phalanges; digits IV and V were reduced, and lacked ungual phalanges. Typical Prosauropod phalangeal formula was 2–3–4–3. The blade-like distal parts of the pubis formed a broad, flat apron. The fifth pedal digit was vestigial; the femur had a longitudinal crest proximal to the lateral condyle. The lesser trochanterwas a weak ripple proximodistally lying on the latero-anterior surface, and the main parts of the trochanter were below the level of the femoral head (Gauffre, 1993).
History and general description
Sauropodomorphs first appeared on the
supercontinentof Pangaeaas small (1.5 to 3 meters long [5 to 10 ft] ) forms during the middle or late Carnian age (the earliest part of the late Triassic). They are known from Brazil("Saturnalia" and " Unaysaurus"), Madagascar(recently discovered), and Morocco("Azendohsaurus").
Prosauropods retained the same body plan, but by the later Early or Early Middle Norian age had doubled in linear dimensions, as indicated by the 4 to 6 meter long (13 to 20 ft) "Plateosaurus gracilis" of the Lower and Middle
Stubensandsteinof Germany. This animal in turn gave rise to other species of " Plateosaurus", and this animal — 8 meters long (26 ft) and around 1,500 kg or more in weight — dominated the Late Norian environment, persisting into the Rhaetian age. Meanwhile in Argentina an even larger prosauropod, " Riojasaurus", served a similar role This animal, 10 meters long (33 ft), was so big it had to walk on all fours. Curiously, in southern Africaat this time the megaherbivore niche was taken not by prosauropods but by basal sauropods, as indicated by " Euskelosaurus", " Melanorosaurus" and "Blikanasaurus", and " Antetonitrus". Interestingly, while sauropodomorphs dominated the Norian and Rhaetian large herbivore niche, the large carnivore niche continued to be ruled by the Crurotarsi(e.g. ornithosuchids and 'rauisuchians').
The end-Triassic extinction killed off the basal sauropodomorphs like "Thecodontosaurus", "Riojasaurus" and species more closely related to sauropods such as "Melanorosaurs" and "Blikanasaurus". However, 'prosauropod' species such as "Anchisaurus" survived, as did true sauropods. While the first sauropods diversified, the early
Jurassicprosauropods radiated out in a number of medium sized (4 to 6 meter long [13 to 20 ft] ) megaherbivores like " Massospondylus", " Lufengosaurus" and " Yunnanosaurus" and were as successful as their late Triassic predecessors.
The prosauropod reign came to an end in the late Early Jurassic. Both prosauropods and anchisaurs died out at the same time, while the basal sauropods survived and continued to radiate.
After Yates (2003) and Galton (2001) [http://dml.cmnh.org/2003Jul/msg00103.html] .
** Infraorder PROSAUROPODA
* Gauffre F.-X. (1993): The Prosauropod Dinosaur Azendohsaurus laaroussii from the Upper Triassic of Morocco. Palaeontology 36(4): 897–908.
* Upchurch, P (1998), The phylogenetic relationships of sauropod dinosaurs. Zool. J. Linnean Soc. 124: 43–103.
* Yates, A. M. (2004) Anchisaurus polyzelus (Hitchcock): the smallest known sauropod dinosaur and the evolution of gigantism among sauropodomorph dinosaurs: Postilla, n. 230, 58 pp.
* Yates, A.M. & Kitching, J. W. (2003) The earliest known sauropod dinosaur and the first steps towards sauropod locomotion. Proc. R. Soc. Lond.: B Biol Sci. 2003 Aug 22; 270(1525): 1753–8.
* [http://www.palaeos.com/Vertebrates/Units/Unit330/330.100.html Prosauropoda] . "Palaeos".
* [http://dml.cmnh.org/2003Jul/msg00103.html Sauropodomorph phylogeny] . (2003) Mickey Mortimer. "Dinosaur Mailing List Archives".
Wikimedia Foundation. 2010.
Look at other dictionaries:
Prosauropoda — Saltar a navegación, búsqueda ? Prosauropoda Rango fósil: Triásico superior Jurásico inferior Sellosaurio … Wikipedia Español
Prosauropoda — Skelettrekonstruktion von Plateosaurus engelhardti aus Trossingen (Exemplarnummer AMNH 6810) im American Museum of Natural History in New York Zeitraum … Deutsch Wikipedia
Prosauropoda — Prosauropodes Anchisaurus … Wikipédia en Français
Prosauropoda — noun the earliest known dinosaurs • Syn: ↑suborder Prosauropoda • Hypernyms: ↑animal order • Member Holonyms: ↑Sauropodomorpha, ↑suborder Sauropodomorpha * * * ˌprō+ no … Useful english dictionary
Prosauropoda — … Википедия
prosauropoda — pro·sauropoda … English syllables
suborder Prosauropoda — noun the earliest known dinosaurs • Syn: ↑Prosauropoda • Hypernyms: ↑animal order • Member Holonyms: ↑Sauropodomorpha, ↑suborder Sauropodomorpha … Useful english dictionary
Prosauropoden — Prosauropoda Lebendrekonstruktion von Plateosaurus Zeitraum Obertrias bis Unterjura 200 bis 150 Mio. Jahre Fu … Deutsch Wikipedia
Prosauropode — Prosauropoda Prosauropodes … Wikipédia en Français
Prosauropodes — Prosauropoda Prosauropodes … Wikipédia en Français