For the first time, researchers at the University of Alberta in
Edmonton, Canada have been able to put a name and a description to an
ancient mammal that still defies classification.
published recently in the Journal of Paleontology provide the first and
only comprehensive account of the creature, named Horolodectes sunae,
for the unusual shape of the crowns of the teeth. Horolodectes lived
about 60 million years ago, soon after the dinosaurs went extinct, in a
period known for its rapid diversification of small mammals. Based on
careful examination of tooth and jaw fragments that have been unearthed
over the past 30 years, the University of Alberta researchers have now
determined Horolodectes was a small fur-bearing animal that measured 10
centimetres in length and due to its powerful jaws, likely had a strong
Most confounding are the animal’s teeth, which resemble in superficial
ways, those of primitive relatives of ungulates, the group of mammals
which includes horses and cows. But despite that link to ungulates,
which are traditionally herbivores, Horolodectes was thought to have
dined on small insects and grubs. "It had sharp crests on the teeth
which formed blades, indicating it was likely carnivorous," said Craig
Scott, a PhD candidate and lead author of the study. Horolodectes means
‘hourglass biter’, in reference to the creature’s peculiar
hourglass-shaped pre-molars, the teeth between the canine and the
molars. The very tall, sharp pre-molars are unlike any others so far
discovered in the mammal world. "There is nothing else with teeth quite
like it," Craig said.
"In an area of North America that’s been
fairly well studied, it’s unusual to have a critter like this pop up.
It’s not known anywhere else, just in Alberta. And it’s quite distinct.
There’s no mistaking it," Scott said.
The first dental specimens
of the creature were unearthed by University of Alberta paleontologists
30 years ago from the banks of the Blindman River in Alberta, Canada.
About 10 years ago, more teeth were discovered at a dig site near
Drayton Valley and on the banks of the Blindman. But the creature
mystified the researchers, who could not positively identify it, and
exactly where it fits into the evolutionary ladder is still unknown.
Horolodectes remains an enigma to this day.
"It’s just too
bizarre to place in any group that we’ve known about previously," said
Scott. "It’s an open question until we can find more of it. We have no
information from a skull or other parts of the body."
University of Alberta. October 2006.