Data for: Africa’s oldest dinosaurs reveal early suppression of dinosaur distribution

The vertebrate lineages that would shape Mesozoic and Cenozoic terrestrial
ecosystems originated across Triassic Pangaea. By the Late Triassic
(Carnian Stage, ~235 Ma), cosmopolitan ‘disaster faunas’ had given way to
highly endemic assemblages on the supercontinent. Testing the tempo and
mode of the establishment of this endemism is challenging—there were few
geographic barriers to dispersal across Pangaea during the Late Triassic.
Instead, palaeolatitudinal climate belts, and not continental boundaries,
are hypothesized to have controlled distribution. During this time of high
endemism, dinosaurs began to disperse and thus offer an opportunity to
test the timing and drivers of this biogeographic pattern. Increased
sampling can test this prediction: if dinosaurs initially dispersed under
palaeolatitudinal-driven endemism, then an assemblage similar to those of
South America and India—including the earliest dinosaurs—should be present
in Carnian deposits in south-central Africa. Here, we report a new Carnian
assemblage from Zimbabwe which includes Africa’s oldest definitive
dinosaurs, including a nearly complete skeleton of the sauropodomorph
Mbiresaurus raathi, gen. et sp. nov. This assemblage resembles those of
other dinosaur-bearing Carnian assemblages, suggesting that a similar
vertebrate fauna ranged high-latitude austral Pangaea. The distribution of
the first dinosaurs is correlated with palaeolatitude-linked climatic
barriers, and dinosaurian dispersal to the rest of the supercontinent was
delayed until these barriers relaxed, suggesting that climatic controls
influenced the initial composition of the terrestrial faunas that persist
to this day.