Evolution repeatedly arrived at similar body plans in unrelated groups
Some 212 million years ago, a small two-legged reptile with a toothless beak moved across what is now New Mexico — an animal that looked like a dinosaur but was, in fact, a distant cousin of the crocodile. The newly named Labrujasuchus expectatus, recovered from the celebrated fossil beds of Ghost Ranch, fills a long-anticipated gap in the record of a peculiar group called shuvosaurids, whose bird-like bodies evolved entirely independently of the dinosaur lineage. Its discovery is a quiet reminder that evolution is not a single road but a landscape of parallel paths, where radically different creatures can arrive at the same shape simply because that shape works.
- A 212-million-year-old skeleton from New Mexico turns out to belong to a bipedal, beaked crocodile relative — an identity so counterintuitive it challenges basic assumptions about what ancient reptiles could become.
- The find closes a frustrating temporal gap between two other known North American shuvosaurids, landing almost exactly where paleontologists had long predicted a missing species should exist.
- Classifying these animals remains difficult because the group changed so little over ten million years — scattered bone fragments across the Chinle Formation often can't be pinned to a species, only to a family.
- A biogeographic puzzle deepens: all named small-bodied shuvosaurids come from the American Southwest, raising the question of whether this lineage was a regional phenomenon or simply better preserved there than anywhere else.
- Ghost Ranch, already one of the most productive Triassic sites on Earth, continues to yield reshaping discoveries even after decades of intensive excavation — suggesting the record is far from complete.
Roughly 212 million years ago, a small reptile walked upright across what is now northern New Mexico. It had a toothless beak, tiny forelimbs, and a body built for speed — the kind of skeleton that, out of context, might easily be mistaken for an early dinosaur. But Labrujasuchus expectatus was something stranger: a member of the crocodile lineage, the same ancient branch that would eventually produce the crocodilians alive today.
The fossil comes from Ghost Ranch, one of the richest windows into Triassic life anywhere in the world. Dated to about 211.9 million years ago, the partial skeleton — shoulder, forelimb, pelvis, hindlimb, spine — places the animal within a small group called Shuvosauridae, creatures that looked almost nothing like what we expect from crocodile relatives. The species name, expectatus, means "awaited" in Latin. Paleontologists had long suspected a shuvosaurid from this precise time interval should exist, bridging a gap between an older Texas species and a younger one found nearby. Labrujasuchus now occupies that middle ground, exactly where theory said it should be.
What makes the discovery remarkable is what it says about convergent evolution. Shuvosaurids were gracile, bipedal, and toothless, yet they belonged to the crocodile line of archosaurs — not the dinosaur line. They resembled ornithomimosaurs, the fast-running theropods that would not appear until the Cretaceous, tens of millions of years later. Unrelated reptiles had independently arrived at the same body plan because that plan worked. "Bipedalism is certainly a unique path for crocodile relatives to take," said lead author Dr. Alan Turner of Stony Brook University, "but it's a path well-trod by dinosaurs and later birds."
The group as a whole shows striking anatomical conservatism — different species looked very similar to one another across roughly ten million years of existence. This makes classification difficult, since shuvosaurid bones scattered across the Chinle Formation and Dockum Group usually appear as isolated fragments rather than complete skeletons. Labrujasuchus can be distinguished from its closest relatives by specific features of the humerus, ischium, fibula, and coracoid, but many other fragments can only be assigned to the family, not to any particular genus.
A biogeographic question lingers. All named smaller-bodied shuvosaurids come from the American Southwest, while hints of related animals from Zambia and India remain too fragmentary to confirm. Whether this reflects a genuinely regional lineage or simply more thorough excavation in one part of the world is still unresolved.
Ghost Ranch itself carries the story forward. The Hayden Quarry alone has produced more than 20,000 vertebrate fossils, and a long-running excavation project there is now in its twentieth year. The genus name Labrujasuchus honors the site's own colorful history — local legend held that rancheros called the area "Ranchos de Los Brujos" to discourage outsiders, and that name now lives on in the fossil record. Each new find from these well-worked beds adds another piece to the larger puzzle of how body plans emerge, persist, and echo across deep time.
In the middle of the Late Triassic, roughly 212 million years ago, a small reptile walked on two legs across what is now northern New Mexico. It had a toothless beak, tiny forelimbs, and a body built for speed—the kind of animal that, if you saw its skeleton alone, you might mistake for an early dinosaur. But Labrujasuchus expectatus was something stranger: a crocodile relative, a member of the same ancient lineage that would eventually produce the crocodilians we know today.
The fossil comes from Ghost Ranch, a site in New Mexico that has become one of the richest windows into Triassic life. Preserved in rocks dated to about 211.9 million years ago, the partial skeleton includes parts of the shoulder, forelimb, pelvis, hindlimb, and spine—enough to show that this animal belonged to a small group called Shuvosauridae, creatures that looked almost nothing like what we expect from crocodile relatives. The species name, expectatus, means "expected" or "awaited" in Latin. Paleontologists had long suspected that a shuvosaurid from this particular time interval should exist, filling a gap in the fossil record between an older species found in Texas and a younger one discovered nearby. Labrujasuchus now occupies that middle ground, exactly where theory predicted it should be.
What makes this discovery remarkable is not that it is unusual—the Triassic was full of unusual animals—but that it reveals how evolution can arrive at the same body plan through completely different routes. Shuvosaurids were gracile, bipedal, and toothless, yet they belonged to the crocodile line of archosaurs, not the dinosaur line. They resembled ornithomimosaurs, the fast-running theropods that would not appear until the Cretaceous, millions of years later. This is convergent evolution in action: unrelated reptiles independently stumbling into similar shapes because those shapes worked. "Bipedalism is certainly a unique path for crocodile relatives to take," said Dr. Alan Turner of Stony Brook University, the lead author of the study published in the Journal of Vertebrate Paleontology, "but it's a path well-trod by dinosaurs and later birds. It obviously worked for these animals."
The fossil itself reveals several diagnostic features that distinguish Labrujasuchus from its closest relatives. The shape of the humeral head, a prominent ventral crest on the ischium, a groove on the fibula, and details of the coracoid all mark it as distinct from Effigia okeeffeae and Shuvosaurus inexpectatus, the other known North American shuvosaurids. Yet despite these differences, the group as a whole shows remarkable anatomical conservatism. Different species may have looked very similar to one another, even though they lived millions of years apart—spanning roughly ten million years, from around 218 million to about 205 million years ago. This makes classification difficult. Shuvosaurid bones are scattered across the Chinle Formation and Dockum Group, but they usually appear as isolated fragments rather than complete skeletons. Because the animals were so similar, many of these fragments can only be confidently assigned to the family Shuvosauridae, not to a specific genus or species.
Ghost Ranch itself has been central to understanding this world. The Hayden Quarry alone has produced more than 20,000 vertebrate fossils, making it one of the richest fossil deposits from this slice of time. The site has yielded lagerpetids, drepanosaurs, phytosaurs, aetosaurs, early dinosaurs, crocodylomorphs, and countless other forms—a menagerie of Triassic life that challenges our intuitions about what ancient reptiles looked like. The name Ghost Ranch itself carries history. According to local legend, rancheros called the area "Ranchos de Los Brujos" to keep people away from the cattle-rustling operations of the Archuleta brothers. The genus name Labrujasuchus honors that colorful past, combining a reference to the old Spanish name with suchus, the Greek word for crocodile.
The discovery also sharpens a biogeographic puzzle. All the named smaller-bodied shuvosaurids come from western North America, particularly the American Southwest, while Sillosuchus, a larger form, remains the only widely accepted member of the group from outside that region. This pattern might suggest that these beaked, bipedal pseudosuchians evolved as a regional lineage, endemic to one part of the world. But the authors are cautious. The pattern could simply reflect uneven preservation or uneven sampling—we may simply have dug more thoroughly in the Southwest than elsewhere. Possible shuvosaurid material from Zambia and India hints that related animals may eventually turn up in other places, but the evidence remains too limited to settle the question.
What matters most is that Labrujasuchus demonstrates how well-studied fossil sites continue to yield discoveries that reshape our understanding of entire ancient lineages. Ghost Ranch has hosted decades of excavation, including a long-running project led by Dr. Nate Smith, now in its twentieth year. Each new find—even from heavily worked quarries—adds another piece to the puzzle of how evolution works, how body plans emerge and persist, and how the distant past speaks to the present. The Triassic was a strange world, full of animals that look almost familiar until you place them on the evolutionary tree. Labrujasuchus expectatus is one more reminder that evolution is far more creative, and far more convergent, than we often assume.
Notable Quotes
Bipedalism is certainly a unique path for crocodile relatives to take, but it's a path well-trod by dinosaurs and later birds. It obviously worked for these animals.— Dr. Alan Turner, Stony Brook University
We see a lot of the successful strategies for modern animals and non-avian dinosaurs first arise in the Triassic, and shuvosaurs are a great example of that convergent evolution.— Dr. Alan Turner
The Hearth Conversation Another angle on the story
Why does it matter that a crocodile relative looked like an ostrich dinosaur millions of years before ostrich dinosaurs existed?
Because it shows that evolution doesn't follow a single path. The same body plan—lightweight, bipedal, toothless—solved a problem for both crocodile relatives and dinosaurs. That's not coincidence. It's a signal that the shape itself was useful.
But if they looked so similar, how do we know they're different animals?
The skeleton tells the story. Labrujasuchus belonged to the crocodile line of archosaurs. Its bones—the shape of the humeral head, the crest on the ischium, details of the coracoid—place it firmly within that lineage, not the dinosaur line. Similar shape, different ancestry.
The paper mentions that shuvosaurids barely changed for ten million years. That seems like a long time to stay the same.
It is, and that's the puzzle. These animals found a body plan that worked so well they didn't need to change it. Different species looked almost identical to each other. That conservatism makes them hard to classify from fragments, but it also tells us something important: once evolution lands on a successful strategy, it can stick with it for a very long time.
Ghost Ranch has produced over 20,000 fossils. Why is this one discovery significant?
Because it fills a gap. Paleontologists knew there should be a shuvosaurid from this time period—between an older one in Texas and a younger one nearby. Finding Labrujasuchus confirms that prediction and gives us a clearer timeline for how the group evolved in North America.
The authors mention that shuvosaurids might have been regional specialists. What does that mean?
It means these animals may have evolved only in the American Southwest, not worldwide. But we don't know for certain. The fossil record is uneven. We've dug more in the Southwest than almost anywhere else. There could be shuvosaurids in Africa or Asia that we simply haven't found yet.