The Real Bigfoot: Behind the scenes with the largest dinosaur foot ever discovered.

An international team of scientists have discovered the largest dinosaur foot ever in the Morrison Formation of the  Black Hills region in the United States. This finding confirms brachiosaurs roamed the land over 150 million years ago. Anthony Maltese is co-author of the new study and discusses the findings published today in PeerJ – the Journal of Life and Environmental Sciences.

Scientific discoveries can sometimes take a long time. In our new paper released this week “The real Bigfoot: a pes from Wyoming, USA is the largest sauropod pes ever reported and the northern-most occurrence of brachiosaurids in the Upper Jurassic Morrison Formation” my coauthors and I report on a huge foot found in the Black Hills region of Wyoming. The discovery itself though was 77 years in the making and was close to never happening at all. Why so long? Here is the inside scoop.

The Morrison Formation is a Late Jurassic rock layer and was one of the first Mesozoic formations to be explored in the United States beginning in the 1870s. Originally field crews focused on areas in southern Wyoming, Utah and most famously in Colorado, where University of Kansas alum Elmer Riggs excavated the first Brachiosaurus specimen in 1901.

As the 20th Century went on, exploration led to the discovery of more geographically far-flung dinosaur-bearing Morrison outcrops, and in the summer of 1941 an expedition from the University of Nebraska found fossils on a remote hilltop in the Black Hills region of Wyoming. This area is more famous for the Lance Creek formation and its late Cretaceous specimens of Triceratops and Tyrannosaurus, and the Morrison in this area was largely unexplored. A short dig discovered the crossed femora of a large sauropod dinosaur but because of timing, the expedition needed to return to Nebraska. The site was secured for the winter with a little plaster but much exposed material. Unfortunately the winter of 1941-42 coincided with the entry of the US into the Second World War. All field activities were curtailed during the wartime and with new students and an incorrect location of the quarry in the records, the site could not be relocated in the late 1940s and 1950s.

Just because the site wasn’t rediscovered doesn’t mean the legend of it died too. The late Larry Martin learned about the quarry while he was a student at the University of Nebraska and brought that knowledge with him to the University of Kansas, where he helped organize an expedition to relocate the site in the early 1990s. Some detective work with local ranchers revealed an old digsite about 2 miles away from where the Nebraska records said it should be, and after securing permission from the landowners, an initial excavation found the crossed femora of the original discovery, complete with remnants of old plaster. X marks the spot! The landowners, noticing the deterioration of the exposed plaster and bones wisely reburied the quarry after the war and protected the site.

The University of Kansas mounted several expeditions to the site in the late 1990s finding several spectacular skeletons of Camarasaurus. While excavating the tail of the “Annabelle” specimen in the summer of 1998, a number of extremely large foot bones were discovered slightly lower in the rocky matrix. I helped prepare these foot bones at the University of Kansas Natural History Museum and two things were immediately apparent: These bones all appear to be from a single individual and that they were REALLY big. But what could they be from?

Our analysis of these bones revealed many things. The shape of metatarsal IV indicated it was a brachiosaur of some sort, however since none of the bones of this foot have any overlap with any Brachiosaurus specimen (to date the only brachiosaur described from the Jurassic of North America) we couldn’t say for sure whether or not this foot is from Brachiosaurus. This determination combined with location of the quarry makes this the northernmost occurrence of a brachiosaur in the Morrison as well. The other thing is that when comparing our measurements with all other published large sauropods, Bigfoot was larger than any other specimen reported. This doesn’t mean it’s the largest dinosaur ever though: many huge sauropods are known from other locations, but these don’t preserve foot material to measure and compare. Indeed, by our calculations Bigfoot was “only” 4 meters tall at the hips and with a length of perhaps 23-24 meters.

While we’re happy that all of these discoveries are now “official” this doesn’t mean work is finished. A few more questions were raised with this research. While preparing the bones I noticed a peculiar texture to the bone surface of all the phalanges, which may have something to do with the immense stresses these bones were put under when the animal was walking. Why this dinosaur had such large feet is also an open question with biomechanical and paleoenvironmental implications. Lastly, there is another smaller skeleton of a brachiosaur from this quarry with some foot material as well as most of the other skeleton, the study of which would help us identify Bigfoot as either Brachiosaurus or possibly something new. I hope my far-flung international cohort of authors and I can work on answering a few more of these mysteries in the coming years.

Read the full paper “The real Bigfoot: a pes from Wyoming, USA is the largest sauropod pes ever reported and the northern-most occurrence of brachiosaurids in the Upper Jurassic Morrison Formation“.

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