Good tidings and well-wishes!
Aside from dinosaurs, pterosaurs, mammoths, and ‘saber-toothed cats’, few groups of ancient fauna can claim strong international fan bases like the various extinct marine reptiles of the world can. You can argue that it stems from the age-old mythology of sea-serpents or that it merely extends from the human fear of the ocean’s depths, but you simply can’t deny the universal appeal of these aquatic beasties. However, as with nearly any paleontological bestiary, nothing sells interest to the general public quite like an intimidating animal of a bygone age: and with all due respect to the plesiosauria, icthyosauria, and thalattosauria (along with many others), no collection of marine reptiles proves to be quite as terrifying to imagine alive as the mosasauridae. (To get an idea of just how monstrous some of these things were, do go here).
Yet every congregation of Goliaths is sure to have its David, and to the mosasaur family, ‘David’ is known as Carinodens sp, a ‘pint-sized’ species of the Netherlands.
At 3.5 meters in length, it’s safe to say that were any of us to find ourselves in the company of Carinodens during a late Cretaceous swim, we’d hesitate before referring to the creature as a ‘dwarf’ of any kind. Yet when one considers the fact that certain mosasaurs may have reached 15 meters from nose-tip to tail-tip, the animal’s miniscule distinction seems appropriate.
As usual, before we can fully appreciate the eccentricities of Carinodens itself, an introduction to the seagoing critter’s phylogeny is required.
The beast belongs to the mosasaurinae subfamily which, according to D.A. Russel in “Systematics and morphology of American mosasaurs” is defined by the following features:
“Small rostrum present or absent anterior [(‘in front of’)] to premaxillary teeth. Fourteen or more teeth present in dentary and maxilla. Cranial nerves X, XI, and XII leave lateral wall of opisthotic through two foramina [(‘openings’)]. No canal or groove in floor of basioccipital or basisphenoid for basilar artery. Suprastapedial process of quadrate distally expanded. Dorsal edge of surangular thin lamina of bone rising anteriorly to posterior surface of coronoid…At least 31, usually 42–45 presacral vertebrae [(meaning ‘those before the hip region’)]present. Length of presacral series exceeds that of postsacral, neural spines of posterior caudal vertebrae [(‘tail vertebrae’)] elongated to form distinct fin. Appendicular elements [(‘those dealing with the arms and legs’)] with smoothly finished articular surfaces, tarsus and carpus well ossified.”
Traditional reconstructions have overwhelmingly depicted globidansine mosasaurs as shell-crushing oyster eaters, although it’s been suggested that cephalopods and arthropods may have been on the menu as well. In 2005, the question of what precisely Carinodens and its relatives ate was visited by the Maastricht Museum of Natural History’s A.S. Schulp, who utilized the discovery of a recently-discovered group of material to create a ‘mechanical mosasaur’ which was designed to crush various marine animals between its jaws. The experiment revealed that
“a biomechanical model of the bite force of Carinodens applied to a mechanical jaw model provides a constraint on the possible prey items this mosasaur could have processed. Echinoids, smaller bivalves, and gastropods are considered to have been likely prey items. Carinodens was probably less successful in crushing larger bivalves such as scallops and oysters which exceeded 100 mm in size. Particularly rounded gastropods, such as winkles, may not have provided sufficient grip to be crushed… The fact that the dentition of Carinodens was well adapted for crushing hard-shelled prey items does not imply that it did not eat softer food. Animals such as shrimp are quite easily processed, so there is no reason to exclude such animals a priori from the menu.”
May the fossil record continue to enchant us all!