A newly described fossil from Ghost Ranch, New Mexico, belongs to the crocodile family tree, but unlike most crocodile-line archosaurs, it walked on two legs, had small arms, and a toothless beak.
Researchers from the Natural History Museum of Los Angeles County and collaborating institutions described the species Labrujasuchus expectatus in the Journal of Vertebrate Paleontology. This animal belongs to Shuvosauridae, a rare group of ancient crocodile relatives that independently evolved body structures similar to those of bipedal, ostrich-like dinosaurs.
Those dinosaurs evolved much later within a separate lineage. Only a small number of shuvosaur species have been identified to date.
The Triassic Era
The Triassic period, which took place about 252 to 201 million years ago, was a time of accelerated evolutionary change. Many major animal lineages began to vary during this period, leading to a range of unusual forms. Along with shuvosaurs, this period saw the rise of lagerpetids, bipedal relatives of dinosaurs whose lineage eventually gave rise to pterosaurs, and Drepanosaurus, a tree-dwelling reptile with a sloth-like claw and a tail that could grasp surroundings. Labrujasuchus lived among this diverse group of animals.
“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,” said Dr. Alan Turner, lead author on the paper. “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.”
The Expected Discovery
The name Labrujasuchus expectatus reflects both the location and the circumstances of its discovery. The genus name comes from ‘Ranchos de los Brujos,’ the old Spanish name for Ghost Ranch, combined with the Greek word suchus for ‘crocodile.’ The species name expectatus is Latin for ‘expected,’ referring to the expectation that this specimen would be found in this area.
Previous discoveries at Ghost Ranch included similar species from both earlier and later Triassic periods. The presence of an evolutionary link between them was expected, and L. expectatus helps fill a gap in the fossil record.
“Finding one shuvosaur from earlier in the Triassic and one from later meant that we paleontologists knew there were probably more from in-between waiting to be discovered and described,” said Dr. Nate Smith, Gretchen Augustyn Director and Curator of the NHMLAC Dinosaur Institute. “We wanted to highlight how the fossil record works.”
Smith also explained the “haunted” history behind the site’s name. Local legend holds that ranchers called the land ‘Ranch of the Witches’ to discourage visitors and protect the cattle operations of the Archuleta brothers. The researchers chose to honor this aspect of regional history with the name they chose.
20 Years at Ghost Ranch
This discovery marks a milestone for the ongoing excavation project at Ghost Ranch, which enters its twentieth year this summer. The site, known internationally through Georgia O’Keeffe’s paintings of its red and ochre badlands, contains four active quarries and has produced some of the most well-preserved Triassic fossils. In 1947, paleontologist Edwin H. Colbert documented more than a thousand well-preserved skeletons of a small Triassic dinosaur known as Coelophysis at this location.
The excavation at Hayden Quarry, where L. expectatus was found, is part of this ongoing project. Each summer, teams of paleontologists and volunteers excavate the site, and each season brings new discoveries, sometimes confirming what researchers already anticipated. The researchers note that long gaps in the species fossil record indicate much of the group’s evolutionary history is still unknown. More “Witch Crocs” may still be out there.
Austin Burgess is a writer and researcher with a background in sales, marketing, and data analytics. He holds an MBA, a Bachelor of Science in Business Administration, and a data analytics certification. His work focuses on breaking scientific developments, with an emphasis on emerging biology, cognitive neuroscience, and archaeological discoveries.