Description and Classification

Sellosaurus was a medium-sized herbivorous dinosaur, typical of the early sauropodomorphs, which were ancestors of the giant, long-necked sauropods like Brachiosaurus and Diplodocus. It likely grew to lengths of about 4 to 7 meters (13 to 23 feet) and would have had a fairly long neck, a small head, a bulky body, and a long tail to help with balance. Its hind limbs were strong and longer than its forelimbs, suggesting it primarily walked on two legs (bipedal), although it might have been able to use its forelimbs for support or grasping food.

In terms of classification, Sellosaurus belongs to the group Sauropodomorpha. Within this group, it is placed in or very close to the family Plateosauridae, which includes the well-known dinosaur Plateosaurus. The close similarity between fossils attributed to Sellosaurus and those of Plateosaurus is why many scientists now believe that Sellosaurus is not distinct enough to be its own genus and should be considered a part of Plateosaurus. If this is the case, features described for Sellosaurus are often characteristics of certain individuals or growth stages of Plateosaurus.

Distinguishing Features

Sellosaurus, or the type of Plateosaurus it represents, had several features common to early sauropodomorphs:

• A relatively small skull compared to its body size, equipped with leaf-shaped, serrated teeth suitable for shredding plant material.
• A long neck, which would have helped it reach vegetation at different heights.
• Strong hind limbs that supported most of its weight, with robust feet.
• Forelimbs that were shorter than the hind limbs but possessed hands with five digits. The first digit, or “thumb,” had a large, sharp claw, which might have been used for defense or for pulling down branches.
• The specific “saddle-shaped” vertebrae that originally inspired its name, though the uniqueness of this feature compared to other plateosaurids is debated.

Paleoenvironment and Diet

During the Late Triassic, the region of Europe where Sellosaurus lived consisted of semi-arid landscapes with seasonal rainfall. There were river systems and floodplains that would have supported more abundant plant life. The dominant plants of this era included conifers, cycads, ginkgoes, and ferns. Sellosaurus was an herbivore, using its long neck to browse on these plants. Its teeth were adapted for stripping leaves and soft plant parts, rather than heavy chewing. It likely foraged in areas where vegetation was plentiful, such as along riverbanks or in fern-covered plains.

Significance and Ongoing Research

Sellosaurus, whether as a distinct genus or as part of Plateosaurus, is significant for understanding the early evolution and diversification of sauropodomorph dinosaurs. These dinosaurs represent some of the first large herbivores to walk the Earth and mark an important step towards the later giant sauropods of the Jurassic and Cretaceous periods. Fossils of Sellosaurus and Plateosaurus provide valuable information about the anatomy, growth, and lifestyle of these early long-necked dinosaurs.

Ongoing research on Plateosaurus, which often incorporates material once assigned to Sellosaurus, continues to refine our understanding of their biology. Studies focus on aspects like their locomotion (how they moved), growth rates (as determined from bone histology), and even potential social behavior, especially since Plateosaurus fossils are sometimes found in groups. The taxonomic debate surrounding Sellosaurus itself highlights how scientific understanding evolves as new evidence is discovered and existing fossils are re-analyzed with modern techniques.