Dinosaurs and their predecessors could have lived side-by-side a new study based on fossils retrieved from Brazil indicates.
Researchers found two small dinosaurs alongside a lagerpetid, which is pegged as a precursors of dinosaurs, and this indicates that the rise of dinosaurs was a more gradual affair than previously believed. The findings are published in Cell Press journal Current Biology.
The fossils of the new lagerpetid (Ixalerpeton) and saurischian dinosaur (Buriolestes) were unearthed from the ~230-million-year-old Carnian Santa Maria Formation, which is said to be one of the oldest known rock units including dinosaur fossils anywhere in the world.
The discovery clearly shows that these animals were contemporaries of each other during the earliest stages of dinosaurs’ evolution. The new lagerpetid specimen also preserves the first skull, scapular, and forelimb elements, plus associated vertebrae, known for the group, the researchers report. Tooth evidence also shows that the first dinosaurs most likely fed on “all kinds of small animals, but most probably not plants,” scientists say.
Those details help to reveal how dinosaurs acquired some of their characteristic anatomical traits. Their analysis also suggests that Buriolestes is one of the oldest known Sauropodomorpha, the group of long-necked dinosaurs that includes sauropods.
The two new animals have already helped to fill important gaps in the evolution of the key anatomical features of dinosaurs. But Langer and his colleagues aren’t done with them yet. They are using CT scans to characterize and describe the animals’ anatomy in even greater detail. They also hope to get an even more precise radioisotopic date on the oldest dinosaur-bearing rocks, and the search for more Triassic fossils continues.