Scientists Found an Ancient Crocodile Relative That Walked on Two Legs and Had a Beak
If you lined up a modern crocodile next to Labrujasuchus expectatus, you probably would not guess they were related at all. The crocodile has four powerful legs, armored skin, and a jaw full of sharp teeth. Labrujasuchus, on the other hand, walked upright on two legs, had tiny arms it likely could not do much with, and had a beak instead of teeth. Yet scientists have confirmed that this strange creature, which lived more than 200 million years ago during the Triassic Period, belonged firmly on the crocodile branch of the evolutionary tree. The discovery, published in the Journal of Vertebrate Paleontology, is turning heads in the paleontology world because it shows just how different ancient animals could be from their modern descendants.
The Triassic Period — which stretched from roughly 252 to 201 million years ago — was one of the most experimentally wild eras in the history of life on Earth. Many of the major animal groups we recognize today, including dinosaurs, crocodilians, and eventually mammals, were only just beginning to take shape. The world was essentially a testing ground for different body designs, and nature was not shy about trying out unusual combinations. Alongside Labrujasuchus, the Triassic was home to Drepanosaurus, a tree-climbing reptile with a giant sloth-like claw and a prehensile tail — a tail capable of gripping, like a monkey's — and Vancleavea, an armored, tank-like aquatic reptile. Evolution during this era looked almost nothing like the neat, predictable process we might imagine from textbook diagrams.
Labrujasuchus expectatus belonged to a small, rare group called Shuvosauridae. Shuvosaurs are particularly fascinating to scientists because, despite being relatives of crocodiles, they evolved body shapes that looked almost identical to a group of dinosaurs called theropods — specifically the ostrich-mimic dinosaurs, which were fast, two-legged runners with beaks and small arms. This is a perfect example of what scientists call convergent evolution, which is when completely unrelated or distantly related animals independently develop the same features because those features happen to work really well. Dolphins and sharks both have streamlined, fin-equipped bodies for the same reason: the ocean rewards that shape. In the same way, the Triassic world apparently rewarded two-legged running enough that both shuvosaurs and dinosaurs arrived at it separately.
Only five shuvosaur species had been identified before this discovery, making the group rare and poorly understood. What made scientists especially excited about Labrujasuchus is that it fills a gap that researchers had actually predicted must exist. Fossil hunters had previously found shuvosaur remains from older rock layers and from younger rock layers in the same region, which meant logic suggested there should be a species in between the two time periods. The species name, expectatus, literally reflects that idea — it comes from a Latin word meaning expected or anticipated. Finding it confirmed a piece of the puzzle scientists had long hoped was out there.
The fossils were uncovered at Ghost Ranch in New Mexico, one of the most important paleontology sites in the world. The ranch sits on land that has been yielding extraordinary Late Triassic fossils for decades. The name Labrujasuchus is itself a tribute to this location — it blends a reference to the ranch's old Spanish nickname, Ranchos de los Brujos or Ranch of the Witches, with the Greek word for crocodile, suchus. According to local legend, that spooky name was invented to scare off outsiders while cattle rustlers operated in the area. Scientists loved the colorful history enough to bake it permanently into this creature's scientific name. Ghost Ranch is also famously associated with the painter Georgia O'Keeffe, who spent decades there and made its dramatic red landscape famous through her artwork.
Dr. Alan Turner, the lead researcher on the project, pointed out that shuvosaurs are a powerful reminder of how evolution keeps finding the same good ideas through different paths. Two-legged walking turned out to be extremely successful — dinosaurs used it, birds inherited it, and now we know that crocodile relatives tried it too, millions of years before modern crocodiles settled into their current four-legged lifestyle. Ghost Ranch has now been an active excavation site for twenty years, and the team there plans to keep digging. Given how many surprises the site has already produced, it is a safe bet that more unexpected creatures are still waiting to be found just beneath the surface.
Source: ScienceDaily