Description and Classification

Dystylosaurus is known only from one incomplete dorsal vertebra. Based on this limited evidence, it would have been a large, long-necked, plant-eating dinosaur, similar to other sauropods from the Morrison Formation. When it was first described, Jensen suggested it might be a type of brachiosaurid sauropod. Later studies, however, have proposed it is more closely related to diplodocid sauropods, a group that includes dinosaurs like Diplodocus and Apatosaurus.

The classification of Dystylosaurus is very uncertain. Many paleontologists consider it a nomen dubium, which means “doubtful name.” This is because the single bone found may not have enough unique features to be identified as a separate genus. There is an ongoing debate, with some researchers suggesting the Dystylosaurus vertebra could actually belong to a young Supersaurus, another giant sauropod found in the same geological formation, or possibly to Barosaurus. If this is true, Dystylosaurus would not be a unique dinosaur genus.

Distinguishing Features

The main feature that led to the name Dystylosaurus was what Jensen interpreted as an extra pair of bony projections, or “beams” (styloi), on the vertebra. These were thought to be involved in how the vertebrae connected with each other. This “double-beamed” structure was considered unique at the time of its discovery.

However, this feature is now viewed with skepticism. It is possible that the perceived uniqueness was due to damage to the fossil or a misinterpretation of its structure. It might also represent an unusual variation within an individual of an already known species, rather than a defining characteristic of a new genus. Without more complete fossil discoveries, it is very difficult to confirm if this vertebral feature truly sets Dystylosaurus apart from other sauropods.

Paleoenvironment and Diet

Dystylosaurus lived in what is now western North America during the Late Jurassic period. Its fossil was found in the Brushy Basin Member of the Morrison Formation in Colorado. During this time, the region was a large floodplain with rivers, seasonal lakes, and open woodlands. The climate was semi-arid, meaning it was mostly dry with distinct wet and dry seasons.

As a sauropod, Dystylosaurus was a herbivore, meaning it ate plants. It likely used its long neck to reach leaves and branches from tall trees like conifers, as well as lower-growing plants such as cycads and ferns. Dystylosaurus shared its environment with many other well-known dinosaurs. These included other large sauropods like Apatosaurus, Diplodocus, Camarasaurus, and Brachiosaurus, and meat-eating theropods such as Allosaurus and Ceratosaurus.

Significance and Ongoing Research

When first announced, Dystylosaurus was considered significant because its unique vertebral structure suggested a new type of spinal anatomy among sauropod dinosaurs. It hinted at a greater diversity in how these giant animals were built.

Today, the main significance of Dystylosaurus lies in the scientific discussions about its validity. It serves as an example of the challenges paleontologists face when classifying dinosaurs based on very incomplete fossil remains. The debate about whether Dystylosaurus is a distinct genus or part of another known dinosaur like Supersaurus highlights the careful process of scientific investigation and revision in paleontology.

Further research on Dystylosaurus would ideally require the discovery of more complete skeletons or at least more bones that clearly show the features of the original vertebra. Until such discoveries are made, its status as a separate dinosaur genus will likely remain uncertain. Scientists continue to study sauropod fossils from the Morrison Formation, and these ongoing studies may eventually provide more clarity on the true identity of Dystylosaurus.