Atlas Mountain Dinosaurs

Fossils from the Atlas Mountains of Morocco have been an enigma since they were first introduced. There has been dubious material sold as Jurassic in age, as well as questionable provenance.

El Mers Group

Originally, the only material collectors generally had access to were indeterminate theropods and the wastebasket taxon, Cetiosaurus mogrebiensis from the Middle Jurassic, El Mers Formation in the Boulemane region. Since then, other dinosaurs have been described from this deposits like the odd stegosaurid, Adratiklit boulahfa. Matrix from this deposits is described as having gypsum crystals. From the few material I have seen and held, the matrix is coarse grained and can have an orange coloration. Fossils from the real El Mers Formation in Boulemane were extremely rare to see on the market prior to the influx of Talsint material.

Dekkar Group

Sometime later, supposed Jurassic material had popped up from the Talsint region in the Figuig Province. Many were labeled as indeterminate ceratosaurid or allosaurid, and while that wasn't technically incorrect, most material turned out to be abelisaurid and carcharodontosaurids of similar, if not identical age to the Kem Kem Group. This became more evident as derived spinosaurid teeth from this region began to pop up as well. This likely Cenomanian deposit is referred to as the Dekkar Group, which produces black colored versions of Kem Kem fauna preserved in marl matrix.

Jurassic Talsint

Any Jurassic sauropod teeth that cropped up around the same time as the Dekkar material were assumed to be from Boulemane just lumped in or mixed together. However, after subsequent material from an allegedly different part of Talsint, there does appear to be fossils different from that of the Dekkar Group and El Mers Group.

It is possible these specimens are not exactly from Talsint, but from the general area of the Figuig Province.

Matrix Comparison

The image above shows a comparison between the Dekkar Group (Left) and the Jurassic Talsint deposit (Right). There is some noticeable difference between the Dekkar Group and Jurassic Talsint, but it is difficult to define or understand what is actually different without a background in geology.

The supposed Jurassic material is also significantly more resistant to being placed in water or acetone. While most of the matrix did eventually fall apart, some larger chunks remained and some sections refused to break apart without excessive force even after 4 weeks in water.

Comparatively, every attempt at trying to fully stabilize Dekkar material has ended up in a large pile of mushy matrix within a minutes, if not seconds of being placed in acetone. While not as effective, brushing the consolidant onto the specimens had a much more desirable outcome.

Another difference is the presence of fairly decent sized crystals in the matrix which may be gypsum also found in the El Mers Group. It's unknown if these larger crystals are also found in material from Boulemane, or if they are unique to this deposit. The gypsum seen in Boulemane material tends to be in smaller flakes; as I am not a geologist, these large chunks may not even be gypsum at all. In general, the "Jurassic" material contains other debris generally not seen in the Dekkar Group.

The image above is a closeup view of the large crystals that broke off from a larger piece found in the Jurassic Talsint matrix of a theropod specimen. More of these crystals are still attached to the matrix. Similar crystals were found on a turiasaurid sauropod tooth from the same region.