New Mexico Quarry Yields Surprise: A Dinosaur No One Knew Existed

For more than 80 years, a fossil quarry at Ghost Ranch in northern New Mexico has been one of the most celebrated dig sites in the world. Best known for producing hundreds of skeletons of Coelophysis, a small, slender meat-eating dinosaur, the quarry seemed well understood. But a new study published in the journal Papers in Palaeontology reveals that something else was buried there all along: a previously unrecognized dinosaur belonging to one of the oldest carnivorous lineages ever identified.

Rather than fading out well before the end of the Triassic, this creature’s presence suggests that some of these early predators were still around, still evolving, right up to one of the worst mass extinctions in Earth’s history.

Named Ptychotherates bucculentus, the new animal belongs to a group called Morphoraptora, a lineage closely related to the earliest carnivorous dinosaurs and sharing traits with a family known as herrerasaurians. Most known members of this broader family come from older rocks in places like Argentina and Brazil, and they had not been clearly identified in rocks from the final stretch of the Triassic anywhere on Earth. Finding one at Ghost Ranch repositions these animals in the timeline of early dinosaur evolution, at least in certain parts of the ancient world.

A Different Kind of Predator at Ghost Ranch

Most people who know about Ghost Ranch associate it with Coelophysis, a lightweight, agile predator that is often among the first dinosaurs children learn about. Hundreds of its skeletons have been pulled from the quarry, sometimes found piled on top of one another in apparent mass-death events. But the ecosystem that existed in what is now New Mexico during the latest Triassic was richer than a single species would suggest.

Ptychotherates belongs to a different lineage within early saurischian dinosaurs, the broader group that includes both long-necked plant-eaters and the two-legged predators that eventually gave rise to modern birds. Its close relatives had a different body plan and likely played a different ecological role than the more lightly built Coelophysis. Their presence at the same site paints a fuller picture of the predator community in this ancient landscape.

Identifying a new species from fossils sitting in museum collections for decades is not unusual in paleontology. Specimens are often collected in bulk during excavations, and it can take generations of researchers to recognize that certain bones belong to something entirely new. Here, a partial skull collected from the quarry by the Carnegie Museum of Natural History turned out to hold the answer. Researchers used CT scanning to digitally reconstruct it, revealing bone features that matched no previously known species from the site. The skull is roughly the size of a standard ruler, and while the reconstruction is detailed and well-supported, some aspects of the animal’s precise family relationships may shift as more material comes to light.

Why the Survival of This Lineage at Low Latitudes Matters

For years, the standard account of early dinosaur evolution went something like this: the earliest carnivorous lineages appeared, thrived briefly, then were largely replaced by newer groups well before the Triassic came to an end. Meanwhile, other dinosaur branches diversified and eventually inherited the Earth after a catastrophic extinction event around 201 million years ago.

Ptychotherates complicates that story in a specific and meaningful way. Its presence in the Coelophysis Quarry, which dates to the very end of the Triassic, shows that at least some members of its lineage were more diverse and longer-lasting in low-latitude regions of the ancient supercontinent Pangea than anyone had recognized. Higher-latitude regions appear to have lost these early carnivorous lineages well before this, replaced by more familiar neotheropods. But in what is now the American Southwest, multiple early carnivorous groups coexisted for a remarkably long stretch of time.

Researchers suggest this region may have functioned as a kind of evolutionary refuge, a place where older lineages held on longer because of the unique environmental conditions near the equator during the late Triassic. Sauropodomorphs, the long-necked plant-eaters thriving elsewhere in Pangea at the time, were notably absent from these same southwestern assemblages, hinting at an ecosystem that simply worked differently. Whether the extinction of Morphoraptora happened precisely at the end-Triassic mass extinction, or shortly before, remains an open question, since the stratigraphic record in southwestern North America has gaps right at that boundary.

What is clear is that the Triassic predator community at Ghost Ranch was more varied than decades of excavation had suggested. Early carnivorous dinosaur lineages were still part of functioning ecosystems right up to one of the most consequential turning points in the history of life on Earth, and a skull sitting in a museum drawer for decades just proved it.

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