Description and Classification

The known fossils of Tichosteus consist only of a few vertebral centra (the main, spool-shaped part of a vertebra). Edward Drinker Cope originally described two species based on these bones: T. lucasanus and T. aequifacies. The vertebrae were noted by Cope for possessing internal bony struts or “walls” within the centrum, which he believed strengthened the bone, and this feature inspired the genus name.

Because the fossils are so incomplete, classifying Tichosteus accurately is extremely difficult. Cope initially suggested it might be an ornithopod dinosaur, a group of usually bipedal herbivores related to dinosaurs like Camptosaurus or Iguanodon. Over the years, other interpretations have been minimal due to the poor material. Without more complete remains, most paleontologists today consider Tichosteus to be an indeterminate dinosaur, possibly an ornithischian, but its exact placement within Dinosauria remains a mystery. Its status as a nomen dubium highlights the challenges paleontologists face when working with very sparse fossil evidence.

Distinguishing Features

Based on Edward Drinker Cope’s original description, the primary feature thought to characterize Tichosteus was:

• The internal structure of its vertebrae, which appeared to have internal buttresses or “walls.”

However, it is now uncertain whether this feature is genuinely unique to Tichosteus, common to a known group but not preserved well in other specimens, merely an individual variation, or even an artifact of how the bone was fossilized. Due to the very limited and fragmentary nature of the fossils, confirming truly distinguishing features that would set Tichosteus apart as a valid genus is not currently possible.

Paleoenvironment and Diet

Tichosteus lived in the Morrison Formation environment of western North America during the Late Jurassic period. This ecosystem was characterized by a semi-arid climate with distinct wet and dry seasons, featuring vast floodplains, river channels, lakes, and open woodlands with ferns, cycads, and conifers. This was a region teeming with a diverse array of dinosaur life.

If Tichosteus was indeed an ornithischian dinosaur, as some early interpretations suggested, it would have been a herbivore, feeding on the available plant life. It would have shared its world with many well-known dinosaurs, including giant long-necked sauropods like Apatosaurus, Diplodocus, and Brachiosaurus; the plate-backed Stegosaurus; other plant-eating ornithopods such as Camptosaurus and Dryosaurus; and carnivorous theropods like the formidable Allosaurus and the horned Ceratosaurus.

Significance and Ongoing Research

The primary significance of Tichosteus today is historical. It is one of many dinosaur genera named by Edward Drinker Cope during the “Bone Wars,” a period of intense fossil discovery and scientific rivalry in the American West during the late 19th century. Tichosteus serves as a classic example of a dinosaur taxon based on extremely fragmentary remains, a situation that often leads to its classification as a nomen dubium.

Due to the scarcity and ambiguity of its fossil material, there is little to no specific ongoing research focused directly on Tichosteus itself. It is generally mentioned in scientific literature only in lists of historical discoveries or discussions about problematic and doubtful dinosaur names from the Morrison Formation. Future discoveries of more complete and clearly associated skeletal remains from the same geological layers might someday shed light on the true identity of Tichosteus, potentially reassigning its fossils to an already known dinosaur or, less likely, confirming it as a distinct type. For now, it remains an enigmatic and minor footnote in the rich history of the Morrison Formation’s spectacular dinosaur fauna.