Prognathodon is an extinct mosasaur genus. It belongs to the Mosasaurinae subfamily, which includes genera such as Mosasaurus and Clidastes. Prognathodon has been discovered in Middle Eastern, European, New Zealand, and North American sediments dating from the Campanian through the Maastrichtian periods.

The name Prognathodon comes from the Latin pro- (“earlier” or “before”), Greek Gnathos (“jaw”), and the Greek Odn (“tooth”) (“tooth”). Prognathodon has twelve identified species, which are found in North America, northern and western Africa, the Middle East, Western Europe, and New Zealand.

The systematics of the genus and which species should rightfully be classified as Prognathodon is disputed due to sometimes obvious differences between them and the partial state of many of the specimens.

A big specimen of Prognathodon was discovered in Israel, albeit it is now classified as a distinct genus, Oronosaurus. The huge jaws and teeth of Prognathodon are well-known. Since its discovery, its unique eating characteristics have piqued curiosity in its ecology, yet direct evidence of its diet, such as stomach leftovers, is rare.

Description

Prognathodon is one of the largest mosasaur genera, with the largest known skull (from P. Currii) being over 140 cm in length. Despite its enormous extent, the genus’ remnants are frequently fragmented and fragmented.

Only a few specimens with articulated skulls and none with a full skeleton have been discovered so far. Many species, such as P. Currii, P. saturator, and P. Overtoni, were huge, with sizes reaching or perhaps exceeding 10 meters. However, many others were much smaller. P. Solvayi, the type species, was the tiniest, measuring only 5 meters in length.

Aside from its size and toughness, Prognathodon is distinguished by its sclerotic rings, which are found in all species of the genus.

The scleral ossicles are responsible for maintaining the curvature of the cornea and supporting the sclera in the Brucke’s muscle region, which affects accommodation in the lacertilian eye.

The sclerotic ring in the type species, P. Solvayi, is only partially maintained, with each ring containing five scleral ossicles. [4] Several other mosasaur taxa, such as Mosasaurus, have similar sclerotic rings.

In the type species, P. Solvayi, the scleral ring is only partially preserved, with each ring containing five scleral ossicles. [4] Sclerotic rings are found in several different mosasaur genera, including Mosasaurus.

The supraorbital wing with heavy triangular ala meets the postorbitofrontal posteriorly over the orbit medial to the external edge of the frontal, and the prefrontal forms a major section of the posterolateral border of the external nares.

A median dorsal ridge is either present or absent, and the frontal does not emarginate above the orbits. Short tongues from the frontal or placed on the frontoparietal suture encircle the foramina on the parietal, which are small to moderately big and positioned anteromedially on a slight eminence.

The dorsal parietal surface’s edges are parallel to each other, and the cranial midline is parallel to the posterior base of the diverging suspensory rami, forming a rectangular space medially on the parietal.

The ventral process of the postorbitofrontal to jugal is indistinct from the moderately well-exposed dorsal surface of the postorbitofrontal, and the Ventral posterior process on the jugal is underdeveloped or missing. The parietal squamosal wing is quite big. The basilar artery runs through a large groove in the floor of the basioccipital.

On the quadrate, the suprastapedial and infrastapedial processes are united, and the tympanic ala is thick. The stapedial pit is elliptical to almost round in shape. The dentary’s posterior process is present, incipient, or absent on the dorsal side, and the dentary ends abruptly in front of the first dentary tooth.

The retroarticular process is rectangular in shape, inflected medially or lacing laterally. The marginal teeth are stout, bicarinate, smooth or striated, and stout, bicarinate, and smooth or striated. Zygosphenes and zygantra are either missing, in the early stages of development, or big and functioning.

Prognathodon is known for having a strong skull. The skull also demonstrates adaptations to a strong jaw musculature.

When compared to other genera, such as Mosasaurus, the ratio between the length of the supratemporal fenestra and the overall length of the skull has previously been used as an improvised assessment for mosasaur bite force and is particularly high in Prognathodon (0.22 in P. Overtoni and P. saturator) (0.19 in M. Hoffmannii). [6]

Similar to the genus Globidens, Prognathodon quadrates contain fused suprastapedial and infrastapedial processes, which may be an adaptation to combat the tremendous stresses experienced by the bone during biting. A powerful bite would have come from strong jaw musculature paired with a small and tall dentary.

The skull of the Prognathodon saturator’s type specimen is virtually complete, except for the anterior section of the premaxilla and the dentaries. Even though most of the front marginal teeth are missing, the preserved roots’ inclination suggests that P. saturator had procumbent teeth, a characteristic shared by P. Solvayi.

The huge pterygoid, as well as numerous other parts of the skull, such as the temporal region and braincase, are all stout in comparison to other species in the genus.

The type specimen of P. Lutugini has a significant amount of the skull preserved, albeit being fragmentary. The specimen was originally believed to have maintained a little piece of the premaxilla, but D.V. Grigoriev (2013)[8] said that the bone could not be discovered at this time and that it is perhaps lost.

Both pterygoids were saved, however, the right one is almost entirely a gypsum restoration with two original teeth at the time. The left pterygoid was more complete than the right, although it lacked all processes save the basisphenoid process. The teeth rose from a thin but prominent vertical ridge on the posterior alveolar edge, which was noticed as being quite tiny.

The ventral surface of the basisphenoid process is smooth, and foramina may be seen above the sixth tooth on the pterygoid’s lateral surface, as well as between the sixth and seventh teeth on the medial surface. Only a few portions of the squamosal bone have been found, but they are laterally compressed and tall, as in other Prognathodon species.

The functioning teeth are positioned Postermodeially to the Subdental crypts. The coronoid is saddle-shaped and has a well-developed posterodorsal process, resulting in a nearly 110-degree angle between the horizontal anterior end and the sub-vertical posterior wing on the dorsal margin of the bone.

Because some experts place P. Lutugini in its own genus, “Dollosaurus,” this combination of features helps in determining that it was truly a Prognathodon species.

Prognathodon species have a wide range of dentition. Prognathodon teeth are typically robust and conical, with blunt, serrated carinae and smooth enamel, and are commonly ascribed to the genus.

Despite this, the type species P. Solvayi has teeth that are notably labio-lingually compressed and gently facetted, as opposed to this type of teeth. There is also some variety in tooth number; P. Solvayi has 12 maxillary teeth and 13 dentary teeth, whilst P. Overtoni has 14 dentary teeth.

P. Solvayi possesses the most distinct teeth among all of the species in the genus. The tooth crowns are typically broad and striated, and the anterior teeth are more procumbent than those of other mosasaurs. The premaxillary teeth are nearly horizontal, while the anterior dentary teeth are just a little less so.

In addition to deep striae, P. Solvayi’s fragmented sample suggests that the tooth crowns were prismatic, with seven to eight prisms on the external surface.

P. Solvayi teeth are slender in the front, broadening and triangular in the middle of the dental ramus, and shrinking in size towards the back, with the last two teeth being stunted.

The tooth crowns are only weakly inflated, and unlike P. Overtoni’s teeth, the teeth grow uniformly in size in an anterior-posterior direction and are less posteriorly recurved. Except for the penultimate tooth base, the teeth in P. Overtoni and other species (such as P. Giganteus) are all very consistent in size (which is larger).

P. Lutugini is another species known for its divergent teeth, though understanding of the teeth is limited to isolated specimens. The teeth that have been discovered are highly bicarinate, with a mild serration on both carinae. The carinae then separate the teeth into lingual and labial surfaces, with the lingual being larger and more convex than the labial.

The teeth have a small posterior and medial Recurvature and, except for tiny creases at the tips of the tooth crowns, have a smooth surface (which distinguishes them from other Prognathodon species). The roots of the teeth are barrel-shaped and are around 1.5 times the size of the tooth crowns. The largest tooth crowns that have been discovered are up to 5.5 cm tall and 2.5 cm wide at the base.

P. Lutugini’s teeth vary in size depending on where they are in the mouth. The anterior pterygoid teeth are known for being relatively large, measuring up to 4.6 cm in height and being comparable in size to the marginal teeth.

All Prognathodon species have a small number of teeth in comparison to other mosasaurs (for example, Prognathodon saturator has 14 teeth in the dentary, 12 teeth in the maxilla, and 6 teeth in the pterygoid).

Prognathodon post-cranial fossils are far rarer than Prognathodon skulls and single teeth. Several vertebrae are preserved in the type specimen of P. Lutugini. Four cervical vertebrae with well-developed anterior and posterior zygapophyses have been preserved. On two cervical vertebrae, functional zygosphenes and zygantra were discovered.

All four vertebrae have hypapophyseal peduncles, which are quite short and finish in little laterally compressed oval facets. These facets are positioned posteriorly on the ventral surfaces of the central and are posteriorly inclined.

The synapophyses are big, anteriorly positioned on the centra, and do not reach below the centrum’s ventral edge. The condyles and cotyles are mildly compressed dorsoventrally.

The cervical vertebrae are nearly the same size as the longest dorsal vertebrae, measuring 7.2 cm in length and 4 cm in height. The specimen has 26 dorsal vertebrae, the majority of which are badly preserved.

Dorsal vertebrae are slightly longer than cervical vertebrae, and the condyles and cotyles, like the cervicals, are mildly compressed dorsoventrally. The dorsal vertebrae have a maximum length of 8 cm and a maximum height of 5 cm.

Many rib fragments, while all fragmentary, were also preserved in the original specimen. From the articular head, two grooves extend along the distal portion of the ribs, but only one groove remains behind the center of the rib.

Louis Dollo described Prognathodon in 1889 based on specimens collected in Belgium. The correct generic name for the taxon is a source of debate. Dollo first mentioned the taxon as “Prognathodon” in his early notes and gave a provisional diagnosis, but then changed the name to “Prognathosaurus” in all of his future works addressing the genus.

Dale A. Russell used the term “Prognathodon” for the first time in a comprehensive study on North American mosasaurs published in 1967, where the priority of Prognathodon was established. Russell also corrected the North American species given to Prognathodon, but only briefly mentioned the Belgian specimens.

Even though the genus’ original remnants were very extensive and the original description was concise, no further research on the type material was done for a century. It’s surprisingly not rare for mosasaur specimens unearthed in Belgium’s Craie de Ciply Formation to lack a thorough initial description of the genus and the species referred to it.

Large amounts of time and effort were usually put into removing and displaying the specimens, but scientific research of them remained limited, with diagnoses and descriptions focusing primarily on odd aspects of their anatomy, such as Plioplatecarpus Houzeaui’s quadrate and tympanic membrane.

Prognathodon Giganteus, named by Dollo in 1904, is one of the mosasaur species with the shortest descriptions, seemingly designed solely to give a name to the mosasaur skeleton for display in the museum hall.

An entire fossil skull was discovered in Maastricht limestone quarries in 1998. It was given the nickname “Bèr” and displayed in the Maastricht Natural History Museum shortly after. A Prognathodon saturator was given to this specimen once it was identified as a Prognathodon.

The skeleton of an animal that was possibly 12 meters long is on exhibit at the Natural History Museum in Maastricht, and it was the first decently complete mosasaur specimen recovered from the Maastricht area since 1957.

For a time, a big specimen discovered in Israel was dubbed “Oronosaurus,” but it was finally identified as P. Currii, a new Prognathodon species. The first fully articulated skeletons of Prognathodon Overtoni were discovered in 2011 in Alberta, Canada, from the early late Campanian (c. 74.5 Ma) Bearpaw Formation.

The mosasaur’s tail fins were preserved in the fossil, demonstrating that Prognathodon, like Platecarpus and other mosasaurs, had a bilobed tail fluke resembling a downturned shark’s tail, the shape of which may have aided the creature in surfacing and attacking prey. The find also supports the notion that later mosasaurs were even better suited to the ichthyosaur lifestyle.

Several substantial chunks of the cranium, as well as parts of the torso and tail of the approximately 13-meter long skeleton, were recovered by museum employees in the days following the discovery.

The age of the specimen was determined to be 67.83 million years, making it around 1.5 million years older than “Bèr” based on stratigraphy. This looks to be the oldest known Mosasaurid specimen from the Maastricht area, and it belongs to the genus Prognathodon, according to what has been discovered. Carlo is the name given to the specimen after the ENCI worker discovered it.