In what can only be described as a classic case of “wait, that’s not your dad,” scientists have re-evaluated a curious fossil that sat in collections for decades, quietly misclassified and presumably wondering if anyone would ever notice. The fossil in question, originally thought to be a member of the rather exclusive club of dinosaur relatives near the origin of birds, has now had its family tree re-sketched into something a little more distant, and entirely less glamorous.
Originally named Caseosaurus crosbyensis and discovered way back in the 1930s, the fossil in question consists of a single bit of hip bone, which is not much to go on if you’re trying to establish paternity across 230 million years. The fossil had been linked to early dinosaur lineages, causing paleontologists to nod knowingly for decades, until modern researchers with better computers and more time on their hands decided to take another look. Their conclusion? Whoops.
The paper, recently published in the journal Palaeontologia Electronica, suggests that Caseosaurus shares more in common with a completely separate lineage of dinosaur precursors known as lagerpetids. These are a group of animals that existed before true dinosaurs evolved, which is paleontology’s way of saying they were the warm-up act before the main event. So while the fossil might not be the glamorous distant cousin of Tyrannosaurus rex, it does have its own mildly interesting place in history as a forerunner to the real showstoppers.
This latest identification is part of a growing trend among paleontologists to go back and take a second look at fossils that were classified before the invention of things like CT scans and universally accepted naming conventions. The new analysis nudges Caseosaurus farther from the dinosaur family tree, placing it among the ambiguous crowd of other early archosaurs. These were the reptiles who, somewhere along the evolutionary line, either turned into dinosaurs or got left behind to feature in obscure academic debates.
“Revisiting early fossils like Caseosaurus is critical because it helps us better understand the evolutionary relationships and origins of dinosaurs,” said Sterling Nesbitt, a paleontologist at Virginia Tech involved in the study. He did not specify whether reclassifying fossils based on a single bone makes him feel more powerful than other scientists, but we can probably assume it does.
The reclassification of this fossil might not make headlines in the same way as a fresh T. rex skull emerging from a mountainside, but in paleontology, even a retribution for mistaken identity is enough to spark debate, funding proposals and just possibly, another round of polite academic bickering at conferences.
Turns out even dinosaurs had complicated family trees they never asked for.