A number of footprints present in western Canada should have come from ankylosaurid ankylosaurs, paleontologists have concluded, making them the primary of their variety found. Though different ankylosaur tracks have been discovered, these symbolize the primary footprints from essentially the most charismatic a part of the household, whose thick armor and deadly sledgehammer-like tail membership have made them among the many most well-known dinosaurs.
Ankylosaurs had been constructed robust, with mighty armor to fend off the fearsome predators of the day. Nonetheless, they diverged into two teams: nodosaurid ankylosaurs with 4 toes per again foot, and ankylosaurid ankylosaurs with three. Extra importantly to most individuals, it was solely the tautologically named ankylosaurid ankylosaurs that had the mighty membership tail they’re thought to have welded like a medieval mace. Their nodosaurid cousins made do with a versatile tail, which appears loads much less helpful for breaking tyrannosauroid shins.
Till now, all of the ankylosaur footprints discovered throughout North America have had 4 toes on their rear toes. Paleontologists couldn’t match these to a particular species identified from its bones, so that they created what is named an ichnospecies, a species identified solely from footprints, which they referred to as Tetrapodosaurus borealis.
The primary three-toed footprints of Ruopodosaurus from Tumbler Ridge, British Columbia.
Picture credit score: Credit score V. Arbour/C. Helm.
A single footprint can get distorted, and a toe print be erased. Nonetheless, quite a few prints have been discovered round Tumbler Ridge, British Columbia, and throughout the Alberta border, a few of which have been studied intimately, with casts made. The three-toed sample for the again toes is evident most often. Prints from the entrance toes have 5 toes, however this may be true of both sort of ankylosaur.
As soon as once more, we will’t know the precise species accountable, however scientists learning these prints are assured it was an ankylosaurid and the ichnospecies has been named Ruopodosaurus clava.
The tracks had been made in what is believed to have been a delta atmosphere composed of a mixture of shallow lakes and closely vegetated lowlands threaded by channels.
Naturally, nobody thought the ankylosaurids, which weighed 2-3 tonnes, had been strolling round too softly to depart a hint. Nonetheless, the age of the prints, at 94-100 million years previous, is revealing, since no ankylosaurid bones have been discovered anyplace in North America between 100 million and 84 million years in the past. This absence has been referred to as the “ankylosaurid hiatus”. Clearly, suspicions of the ankylosaurids’ continental demise had been exaggerated, if not fully flawed. The discover proves the continent and even the Peace River space of the Rocky Mountains had been capable of help nodosaurids and ankylosaurids concurrently, with out one displacing the opposite.
“Whereas we don’t know precisely what the dinosaur that made Ruopodosaurus footprints seemed like, we all know that it will have been about 5-6 metres lengthy, spiky and armoured, and with a stiff tail or a full tail membership,” mentioned Dr Victoria Arbour of the Royal BC Museum in an announcement.
Royal BC Museum curator of palaeontology Dr Victoria Arbour with the Ruopodosaurus holotype within the area at Wolverine River, Alberta in August 2023.
Picture credit score: Royal BC Museum
The findings increase the likelihood that another three-toed footprints, which have beforehand been allotted to very totally different dinosaurs, may also be from ankylosaurids.
The identify means “tumbled-down lizard with a membership”, referring to the well-known tail and the steep mountains across the websites the place the tracks had been discovered.
“Ever since two younger boys found an ankylosaur trackway near Tumbler Ridge within the yr 2000, ankylosaurs and Tumbler Ridge have been synonymous. It’s actually thrilling to now know by way of this analysis that there are two varieties of ankylosaurs that referred to as this area residence, and that Ruopodosaurus has solely been recognized on this a part of Canada,” mentioned Dr Charles Helm of the Tumbler Ridge Museum
The research is revealed within the Journal of Vertebrate Paleontology
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