These miners who worked at the Ipswich coal mine in Australia in the 1960s must have come across a big surprise. There were traces of “birds” that were quickly attributed to the track of a dinosaur. The whole question is to know which animal can leave these marks. A new analysis makes it possible to answer them.
no big raptor
For nearly fifty years, paleontologists speculated that these footprints, or rather counterprints, as they appear in three dimensions on the ceiling, were deposited 220 million years ago by a large theropod dinosaur of the raptor type. According to earlier analyses, the animal must have measured at least two meters in height, making it the largest known theropod of the late Triassic. But many experts doubted the accuracy of these findings, especially since they were based not on direct examination of prints but on drawn representations and some photographs. No one can use it anymore since the mine was abandoned in 1964, but just before it was closed a team of geologists from the Queensland Museum mapped the track and molded the footprints.
How are counterprints made?
Counterprints are three-dimensional convex casts formed by a series of processes of petrification, erosion and human intervention. The dinosaur that left its mark was walking on land made of plant debris, which had become hollow under its weight. Later these pits were filled with silt or sand. After millions of years the plant layer turned to charcoal which was extracted by the miners, revealing the impressions corresponding to the clay castings of the upper layer.
It was these genera studied by an international team led by Anthony Romilio of the University of Queensland, a paleontologist who has spent much of his career tracking Australian dinosaurs and their footprints. From the artists, they created a virtual 3D model of the dinosaur’s footprint, which was emailed to team members around the world for study. Their findings published in the journal historical biologyEnd 50 years of misinterpretations.
3D image of a 220 million year old footprint. credit: Anthony Romilio.
but a good sized veg
“The more we examined the size and proportion of footprints and toes, the less they resembled the tracks left by predatory dinosaurs, the more monstrous dinosaur was undoubtedly the friendlier plant eater,“The dinosaur in question is a prosauropod that was supposed to measure 6 meters long on the legs and 1.4 meters high,” Hendrik Klein of the Souriervelt Palaeontologisches Museum in Berlin and a co-author of the study explains in a press release. These animals, herbivores with long necks, were huge. There are distant complexes of dinosaurs that lived millions of years later, such as titanosaurs or diplodocus. The traces left at Ipswich represent the earliest evidence of the presence of this family of dinosaurs.
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