Troodon tricks and dino hips: discovery reveals new dinosaur classification

A University of Alberta Master’s student has stirred up the paleontology world with the discovery of hip bones from a carnivorous dinosaur which lived 75 million years ago.

During a brief visit to help Philip Currie on a dig in Dinosaur Provincial Park in the summer of 2013, Aaron van der Reest uncovered a strange pair of hip bones from a dinosaur species called Troodon formosus.

“This didn’t look like anything we’d ever seen before,” van der Reest said.

What made this particular find so interesting was that unlike other Troodon hips, the pelvic bone on this specimen was turned back slightly, rather than straight down. This discovery led van der Reest and Currie to turn to previously found Troodon cranial bones and examine these to search for any other differences in Troodon individuals. Eventually, they came to the conclusion that what paleontologists had originally assumed to be one Troodon species in Dinosaur Provincial Park, was at least two. This makes the Troodontid classification invalid.

“Right from the very beginning (Troodontids) been a very mysterious group,” van der Reest said. “This really fills in the picture for what these dinosaurs looked like.”

For years, paleontologists had been finding Troodon remains in North America and Asia, but if these fossils records which spanned millions of years were indeed all from an identical species, that would mean that Troodon had lived for 15 million years.

“This was impossible,” van der Reest explained. “Animals just don’t live that long.”

His discovery of the Troodon hips confirmed this long held suspicion. The two dinosaurs, Latenivenatrix mcmasterae and Stenonychosaurus inequalis, were their own species.

“(Latenivenatrix) would have stood and looked me in the eye at 6’3, this thing is two feet taller (than Stenonychosaurus),” van der Reest said.

Latenivenatrix replaced Stenonychosaurus either through ecosystem change, or direct competition, according to van der Reest. He suspects that between now and the next five years, three or four more species are likely to be discovered.

“We’re actually working on ones from Alaska that are likely going to be a new taxa,” van der Reest said.

Lateniventarix mcmasterae, the dinosaur which the hip bone belonged to, lived 75 million years ago and looked like your classic raptor with long claws, small speedy feet, a feathered body, and huge eyes likely for seeing in the dark.

“It would have looked a lot like the raptors that you would see in Jurassic Park,” van der Reest said. “Except they tend to be less bulky.”

The Lateniventarix mcmasterae would have likely been some of the fastest and smartest dinosaurs alive at the time. Six feet tall and four metres long, with an agile build and the largest brain to body size ratio of dinosaurs of their era. They lived in a lush swampy land, on the coast of a shallow sea. The climate was not dissimilar to what you’d find in the Mississippi delta today.

The next step for van der Reest in investigating these animals has been examining bone fragments from Latenivenatrix mcmasterae’s  hip. Here they have found what appear to be preserved blood vessels and cells. Van der Reest hopes that this discovery will assist him in finding preserved proteins to determine more accurate phylogenetic relationships for both North American and Asian Troodontids.

Up until his return to school in 2012, van der Reest had been doing environmental consulting, and had started his own business preparing and casting fossils. He said his fascination with dinosaurs began with a stegosaurus Halloween costume his mother made for him when he was three, complete with stuffed spines and plates. He was hooked on dinosaurs from that point on. So when his mother surprised him by bringing him to meet famed paleontologist Phil Currie at a speaking event when he was 14, he was thrilled and kept in contact with the paleontologist.

Van der Reest named his discovery Latenivenatrix mcmasterae after his mother who had passed away a year before.

“It was one of those bittersweet things. It gave me the opportunity to come back (to school),” Van der Reest said.

Olivia DeBourcier

Olivia deBourcier is in her third year of environmental and conservation sciences, and has spent the last year writing and illustrating for The Gateway. An avid lover of science communications, she would happily talk your ear off about animals, bugs, environmentalism, or which Star Wars movie is better, but she's usually find her running to a meeting she’s already late for.

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