Fossils of Lystrosaurus, a dicynodont therapsid, are most common in parts of mod
ID: 9950 • Letter: F
Question
Fossils of Lystrosaurus, a dicynodont therapsid, are most common in parts of modern-day South America, South Africa, Madagascar, India, South Australia, and Antarctica. It apparently lived in arid regions, and was mostly herbivorous. It originated during the mid-Permian period, survived the Permian extinction, and dwindled by the late Triassic, though there is evidence of a relict population in Australia during the Cretaceous. The dicynodonts had two large tusks, extending down from their upper jaws; the tusks were not used for food gathering, and in some species were limited to males. Food was gathered using an otherwise toothless beak. Judging from the fossil record, these pig-sized organisms were the most common mammal-like reptiles of the Permian.2. Which of these is the most likely explanation for the modern-day distribution of dicynodont fossils?
A)The dicynodonts could survive for periods of months aboard "rafts" of vegetation, which carried them far and wide, but not to the northern hemisphere.
B) The dicynodonts were able to swim long distances, up to thousands of kilometers.
C) The dicynodonts were evenly distributed throughout all of Pangaea.
D) The dicynodonts were distributed more abundantly throughout Gondwanaland than throughout any other land mass.
E) There had been two previous super-continents that existed at different times long before the Permian period.
Explanation / Answer
From the website http://eonsepochsetc.com/Mesozoic/Triassic/Tri_Animals/Dicynodonts.html Lystrosaurus - When Pigs Ruled the World A beaked dicynodont from the Late Triassic, Placerius reached lengths of 10 feet. (www.nmnaturalhistory.org/triassic/c_labels.html)The fossilized remains of Lystrosaurus, a pig-sized dicynodont, are found in the Permian-Triassic strata in the Karoo region of South Africa. During the Early Triassic this one single genus comprised 95% of all fauna found not only in South Africa, but India, China, South America, Russia, Antarctica, and Australia – and probably all of Pangaea! Thus, the answer is letter 'C'==>> even distribution throughout Pangaea