Spinosaurids & Crocodylomorphs

Spinosaurids were predatory theropods with unusual adaptation that may have helped them survive in environments rich in fish and other aquatic prey. Naturally, there are convergent similarities between spinosaurids and aquatic crocodylomorphs. Particularly, the teeth can sometimes be difficult to distinguish, especially those of baryonychines.

The image above shows a comparison of the serration/denticle shapes of the crocodylomorphs, Mahajangasuchus (Top Left) and Sarcosuchus (Top Right), and the spinosaurid, Suchomimus (Bottom Row).

Some of the characteristics of baryonychine teeth like Suchomimus and Baryonyx is their vein-like enamel texture, fluting, and serrations. These teeth are a bit trickier to distinguish from contemporary crocodylomorphs that may have one or two shared characteristics, typically fluting and "serrations". Some tooth positions of crocs like Sarcosuchus, Elosuchus, Hamadasuchus and others are known for their false-serrations or ziphodont teeth. Fluting is a much more common trait seen in both groups.

The image above shows a comparison between a pair of Suchomimus teeth (Bottom Left) and a pair of unknown Jurassic crocodylomorph teeth (Top Left). The right image shows a closeup view of the crocodylomorph tooth showing misleading fluting.

Suchomimus teeth in particular can be easily mistaken for currently indeterminate Middle Jurassic crocodylomorphs from the Irhazer Group. The issue largely comes from the younger fossils from the Elrhaz Formation being mixed together with material from the Tiourarén or Irhazer II Formations. These three formations are very close together, and sometimes very difficult to separate them once they are mixed together. Though Elrhaz material can usually be distinguished by their unique polished-look and color of their preservation.

Spinosaurus & Sarcosuchus

Contrary to popular belief, Spinosaurus did not live with Sarcosuchus, but rather Elosuchus, while Sarcosuchus was contemporary with a different spinosaurid known as Suchomimus. In fact, Spinosaurus did not live with Ouranosaurus either; ornithischians were essentially non-existent in the younger Kem Kem Group and equivalent Dekkar Group.

Genera like Sarcosuchus and Ouranosaurus were extinct by the time Spinosaurus appeared. Most teeth from the Kem Kem Group sold as Sarcosuchus are likely Elosuchus, or some other crocodylomorph.

Fortunately, both the Kem Kem Group and Elrhaz Formation that contain Spinosaurus and Sarcosuchus respectively are available to collectors. The latter however is likely to become much more difficult to obtain in the future.