Your Daily Fossil

Europasaurus

Reconstruction by Gerhard Boeggemann

When: Jurassic (~ 156 - 151 million years ago)

Where: Germany

What: Europasaurus is the smallest sauropod known. Now remember I said smallest SAUROPOD known, so we are still looking at an animal that was about 20 feet (~6 meters) long. Keep in mind though, this includes the long neck and tail - taking those out of the picture and the animal’s body length was about 6.5 feet (~ 2 meters).  This length, coupled with the shoulder height of Europasaurus ( about 5 feet [~1.5 meters]), gives us a sauropod with a body that was about the size of a modern elephant.  There are a number of proposed tiny sauropods out there, but I have selected Europasaurus as it is known from several almost complete skeletons, from juveniles to adults, so we can be sure this is not just a baby sauropod that would have grown much larger. Above I have included a diagram from the original description of Europasaurus rather than a reconstructed mounted skeleton to show you just how much of the skeleton is known. Why is Europasaurus so small? Its our good friend Island Dwarfism back again! The specimens have been found in Germany, on what would have been one of many islands in the area during the late Jurassic, owing to the higher sea levels. 

This smallest of all sauropods is in the clade  Macranaria within the sauropod family tree. This group actually contains some of the biggest sauropods (and thus dinosuars) ever known! Talk about some size diversity within a group! An adult Europasaurus could have easily walked between the legs of some of its larger cousins. The great range of ages in the recovered specimens of Europasaurus have allowed for detailed study of the microstructure of the bones, revealing how these animals grew. From this study it has been proposed that Europasaurus  managed to stay small on its restricted island habitat by not stopping its growth exceptionally earlier than its relatives, but instead by dramatically slowing down its growth rate. 

I hope this cute little sauropod makes up for ruining all of those childhoods with the reality (or should I say unreality) of Brontosaurus a few posts ago. ;) 

Brontosaurus 

Mounted skeleton was on display at the American Museum of Natural History

Reconstruction by Charles Knight

When: Holocene (1879 to 1903) 

Where: Scientific literature and museums on the east coast of the USA. Found even today in public consciousness and outdated dinosaur books. 

What: Brontosaurus is perhaps the most well known of the sauropod dinosaurs. Too bad it never really existed!  The history of this name and why it became so popularized starts in 1877 when the paleontologist Othniel Charles Marsh applied the name Apatosaurus to a sauropod specimen. This specimen was not very complete and mostly represented by vertebrae and a pelvis.  Two years later he erected the name Brontosaurus based on an almost complete skeleton that was missing its head.  Headless sauropod skeletons are fairly common, but in this case this missing head only served to make the story even more complicated.

This missing head was obviously a problem when the skeleton of Brontosaurus was mounted for display at the American Museum of Natural History. There was great debate over which head to use, which some camps wanting to use one that resembled Diplodocus but others rallied behind a Brachiosaurus type skull. This latter skull was what  Marsh had envisioned in his publications on Brontosaurus, so after much heated debate a Brachiosaurus type skull was attached to the previously headless skeleton. This skeleton was unveiled to the public in 1905 to great fanfare and soon after the a few other museums around the world had their own Brontosaurus on display, with an identical head to the Yale specimen. 

So the general public had a firm concept of the dinosaur Brontosaurus! It was an easy to remember and pronounce name, this is what it looked like, and hey look we even have all of these lovely reconstruction showing these great lumbering beasts in prehistoric swamps. Too bad everything was wrong. And even worse, it was KNOWN to be wrong by some workers who were shouted down by others. In 1903, two years before the specimen was mounted at Yale,  a paper was published Elmer Riggs at the Field Museum of Chicago that declared that the bones known for Apatosaurus that overlapped with those of Brontosaurus showed that these two animals were the same. He concluded that Brontosaurus was not a valid name as it was two years younger than Apatosaurus. Even worse, remember the great head debate? Totally wrong. Later fossil finds have confirmed that a Diplodocus style head should have been used. These skulls are much more elongated and flatter than the high domed skull that was used for the Brontosaurus mount. 

So not only is the name not valid, but the anatomy of the animal isn’t even anything that ever existed in nature! It is a chimera of different species. Also sauropods were not aquatic swamp dwellers, they were 100% terrestrial creatures. 

Poor Brontosaurus. 

Plateosaurus 

Mounted specimen at the Institute for Geosciences of the Eberhard-Karls-University Tübingen, Germany

When: Late Triassic (214-204 million years ago)

Where: Central and Northern Europe

What: Plateosaurus is one of the first dinosaurs found, named in 1837, making it the 5th named genus that is still valid today. However, this species was not included in the initial formation of the clade in 1842 as it was based upon material too fragmentary to confidently identify it as a dinosaur. This is far from the case today, as Plateosaurus is one of the most well known dinosaurs, with over 100 partial (and some complete) skeletons known, most from Germany.  

Plateosaurus is a basal sauropodomorph, which means it falls on the lineage that gave rise to the sauropods. The first of the Saurischia (theropods + sauropods) were bipedal, and we can see from Plateosaurus (and other sauropodomorphs) that the lineage became herbivorous before dropping down onto all fours and increasing to gigantic sizes. Plateosaurus was not only able to walk on just its hind legs, it was quite an adapt runner. The largest Plateosaurus reached 33 feet (10 meters) long and are estimated to have weighed over 8,500 lbs (4,000 kg).