sauropods were the largest animals to ever walk the Earth, and they're sometimes called 'thunder lizards'.
Four strong legs were needed to support and transport the huge bodies of these giants. Most of the time. Maybe.
The tracks described in the study could offer new support for the view that the lumbering giants sometimes got around on two legs, not four, belying what their quadruped status would seem to demand.
There are Sauropod footprints at the trackways. The museum is in the Texas Hill Country.
The hypothesis dates back several decades, to when fossil researcher Roland T. Bird identified some unusual dinosaur tracks on ranch grounds.
The marks on the tracks were only manus, not the rear limbs, which are known as pes.
Bird wrote a letter in 1940 in which he said that they were made by an individual while swimming.
The forefeet impressions were similar to the way the animal had just been kicking.
Modern paleontology came to realize that sauropods were mostly land animals, not aquatic as was once thought, and Bird's interpretation of these tracks fell out of favor.
The forefeet of sauropods leave marks on certain ground surfaces, as the rear limbs leave less impression on soil, which is the alternative view to explain manus-only tracks like this.
A playful exploration of the punting hypothesis. The illustration was created by R.T. Bakker/Farlow and Ichnos.
The case for dinosaurs treading through shallow, shoulder-height bodies of water on their front limbs has never been ruled out.
The merits of the arguments were given a chance to be reconsidered.
The marks were first found in a limestone quarry in 2007, which is part of the Glen Rose Formation, a geological site that preserves numerous dinosaur footprints dating back over 100 million years ago.
Several dozen individual footprints were preserved for study before the surface layers were removed for commercial purposes, and three different trails of parallel, manus-only sauropod trackways were investigated at the site by teams from Purdue University Fort Wayne and the Houston Museum of Natural Sciences.
While we don't know what kind of sauropods left these manus-only marks, the researchers highlighted the possibility that it could be a different kind of dinosaur to the ones that left other manus-only footprints in the Glen Rose Formation.
It is likely that the tracks belonged to sauropods, and the trackmarks look to be 'true tracks' left on the upper surface.
The researchers said it's impossible to know if the marks support the idea of differential foot pressure or if it's just something else.
The authors wrote that the Coffee Hollow trackways are likely to be explained by the differential pressure exerted by the fore feet than the hind feet.
R.T. Bird might have been correct in thinking that swimming would not necessarily involve unusual behavior. The sauropod trackways were made by dinosaurs that were wading in water deep enough for their makers to punt, pulling themselves along by their fore feet, while their hind legs floated above the bottom.
The punting sauropod still has a chance to wade into reality, as the team said future discoveries will be needed to settle the matter.
Ichnos has the findings reported.
January 2020 is when the first version of this story was published.
