Lystrosaurus

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Lystrosaurus
Fossil range: Early Triassic
Lystrosaurus murrayi
Lystrosaurus murrayi
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Synapsida
Order: Therapsida
Suborder: Anomodontia
Infraorder: Dicynodontia
Family: Lystrosauridae
Genus: Lystrosaurus
Species
  • Lystrosaurus curvatus
  • Lystrosaurus declivus
  • Lystrosaurus mccaigi
  • Lystrosaurus murrayi
  • Lystrosaurus oviceps
  • Lystrosaurus platyceps

Lystrosaurus (meaning 'shovel lizard', pronunciation in IPA: /ˌlɪstrɒˈsɔrəs/) was a genus of Early Triassic Period therapsids, which lived approximately 250 million years ago in what is now Antarctica, India and South Africa. It was a common synapsid, a group of animals ancestral to (and including) mammals, more frequently referred to as mammal-like reptiles. More specifically it was a dicynodont (which means "having two dog-teeth", a characteristic of one sex, supposedly males). Lystrosaurs were heavily-built barrel-chested medium-sized (about a meter long) herbivorous animals, approximately the size of a pig, with very stout limbs. Their teeth had become reduced to two long tusks protruding from their upper jaws. Originally they were thought to be amphibious, a sort of small reptilian hippopotamus, but some more recent evidence indicates that they lived in arid environments, which were becoming increasingly common as the Triassic unrolled.

Contents

[edit] Dominance of the Early Triassic

Lystrosaurus is notable for dominating southern Pangea during the Early Triassic for millions of years. At least one species (unidentified) of this genus survived the end-Permian mass extinction and, in the absence of predators and other herbivorous competitors, went on to thrive and re-radiate,[1] becoming the most common group of terrestrial vertebrates during the Early Triassic; for awhile 95% of land vertebrates were Lystrosaurus.[2][1] It is the only time a single species or genus of animal dominated the Earth to such a degree.[3] Some believe that Lystrosaurus survived the Permian-Triassic extinction event due to its adaptation for subsisting on more resilient plant material and, possibly, by being able to breathe the Permian/Triassic noxious atmosphere due to burrowing and its barrel chest.[2] Others attribute its survival to luck.[1]

[edit] Plate Tectonics

Its discovery at Coalsack Bluff in the Transantarctic Mountains by Edwin H. Colbert and his team in 1969-70 helped confirm the theory of plate tectonics and convince the last of the doubters, for Lystrosaurus had already been found in the lower Triassic of southern Africa as well as in India and China.[4]

[edit] Notes

  1. ^ a b c Michael J. Benton, When Life Nearly Died. The Greatest Mass Extinction of All Time, 2006, ISBN 050028573X
  2. ^ a b The Consolations of Extinction: includes section on Lystrosaurus and end-Permian extinction
  3. ^ BBC: Life Before Dinosaurs
  4. ^ Naomi Lubick, Investigating the Antarctic, Geotimes, 2005.

[edit] Gallery

Distribution of Lystrosaurus (brown) on the Gondwana supercontinent.

Lystrosaurus murrayi

Lystrosaurus georgi

Lystrosaurus mccaigi.

[edit] External links