We have two ancient beasts for your delectation today, one large, one small.
Let’s start with the big one, and it really is a monster. Researchers from the University of Oslo’s Natural History Museum have uncovered the skull of a 147 million year-old marine reptile that measured 15 metres in length.
The pliosaur would have weighed in at 45 tonnes, say the researchers. That’s fifteen times the (fictional) weight of Jaws!
“There is nothing really comparable in the sea today,” says Jorn Hurum, one of the team behind the find (NY Times). “Thank God for that,” says I.
Based on the skull, the team believe the beast had a bite force of 15 tonnes per square inch. “With a skull that’s more than 10 feet long you’d expect the bite to be powerful but this is off the scale,” says Joern Hurum (Reuters). “It’s much more powerful than T-Rex.”
Found on the Arctic island of Svalbard, the beast has been given the TV-friendly name ‘Predator X’, which also happens to be the name of a documentary following the researchers who uncovered it. A paper on the find is promised later this year.
At the other end of the scale is Hesperonychus elizabethae. This is being widely reported as the smallest dinosaur ever discovered in North America, although it is described this week in PNAS as the “smallest carnivorous, nonavian dinosaur”.
“When the specimen was first collected, it was so small that it never even occurred to the collector that this was a dinosaur, even though she had collected lots of dinosaurs before,” says study co-author Phillip Currie, of the University of Alberta (National Geographic).
Hesperonychus elizabethae stood about 50 cm tall and weighed only two kg. The mini-raptor would have stalked small mammals and insects says Nick Longrich, of the University of Calgary.
“Small carnivorous dinosaurs seemed to be completely absent from the environment, which seemed bizarre because today, the small carnivores outnumber the big ones,” he says (press release). “It turns out that they were here and they played a more important role in the ecosystem than we realized. So for the past 100 years, we’ve completely overlooked a major part of North America’s dinosaur community.”
The BBC points out that smaller dino-bones are more likely to be washed away or chomped up by scavenging larger animals. The Globe and Mail notes that there has been a collection bias with dinosaur species.
“When we first started working with dinosaurs in Alberta, everybody came here to collect big specimens because they are good display specimens,” Currie told the paper. That however has given “a very skewed understanding of the old ecosystem, where just about everything is big”.
Image top: pliosaur attacking plesiosaur / Atlantic Productions
Image lower: Hesperonychus claw on Canadian quarter (US$0.2) / U. Cal