The newly-discovered species belongs to the mosasaurid genus Carinodens, and was a durophage, adapted for crunching hard-shelled invertebrates.
An artist’s impression of a mosasaur. Image credit: Nick Longrich.
Carinodens is a extinct genus of Cretaceous mosasaurs known from around the world.
These marine lizards measured 2-3 m in length and were unusual in having low, rectangular, compressed teeth.
“Early, basal mosasaurids had small, conical, and recurved teeth, an adaptation for preying on relatively small prey such as fish and soft-bodied cephalopods,” University of Bath paleontologist Nicholas Longrich and his colleagues wrote in a paper in the journal Diversity.
“By the end of the Cretaceous, mosasaurids had evolved highly diverse tooth morphologies.”
“These included massive, conical teeth for seizing and tearing apart prey, blunt teeth for crushing bone, knifelike and bladelike teeth for stabbing and cutting large prey, sawlike teeth for cutting, and low and bulbous teeth for crushing hard-shelled invertebrates.”
“Some of the most unusual tooth morphologies are seen in the durophagous mosasaurid genus Carinodens, a highly specialized mosasaurine appearing worldwide in the Maastrichtian age.”
“Carinodens is characterized by relatively small size, long and slender jaws, and a tooth morphology that is unique among mosasaurids, or other vertebrates.”
“The teeth are relatively low in profile, being longer anteroposteriorly than high, mediolaterally compressed, with a prominently projecting anterior carina and finely anastomosed enamel.”
The new mosasaur species lived during the latest Maastrichtian age of the Cretaceous period, around 67 million years ago.
Named Carinodens acrodon, it coexisted with two more derived Carinodens species: Carinodens minalmamar and Carinodens belgicus.
Its fossilized remains were found in the Sidi Chennane phosphate mine in Khouribga province of Morocco.
“Carinodens acrodon is characterized by teeth with tall crowns, triangular apices, and broad bases,” the paleontologists wrote in the paper.
“Many of the diagnostic features of this species appear to be plesiomorphies, suggesting the persistence of a primitive species of Carinodens into the latest Maastrichtian alongside the more derived Carinodens minalmamar and Carinodens belgicus.”
“It is also the first Carinodens known with well-preserved upper and lower jaws, helping to expand our knowledge of this enigmatic animal.”
While both Carinodens belgicus and Carinodens minalmamar have been reported from many different localities, Carinodens acrodon is so far known only from Morocco.
“Carinodens was highly diverse and widespread in the Maastrichtian, suggesting a rapid radiation into a new niche as a small durophage, but the diet and feeding strategy of Carinodens remain unclear,” the researchers concluded.
“Mosasaurid diversity in Morocco is exceptional and suggests that they continued to radiate until just prior to the end-Cretaceous mass extinction, and that mosasaurids may have been more speciose and diverse in ecology than other Mesozoic marine clades.”
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Nicholas R. Longrich et al. 2025. A New Species of the Durophagous Mosasaurid Carinodens from the Late Maastrichtian Phosphates of Morocco and Implications for Maastrichtian Mosasaurid Diversity. Diversity 17 (1): 25; doi: 10.3390/d17010025