ANYTHING MOSASAUR
MOSASAUR SNEEZE
At the 2015 Society of Vertebrate Paleontology (SVP) meeting in Dallas, I presented my preliminary work on salt glands in mosasaurs using the mosasaur skull shown above, Phosphorosaurus ponpetelegans. Kidneys of marine reptiles, such as sea turtles, are incapable of producing highly concentrated urine, necessitating them to have special salt glands to get rid of excess salt they ingest with their food from the sea. All the living marine reptiles including seabirds possess salt glands in their heads, and in the case of marine iguanas, they use nasal glands for this purpose, where they sneeze to rid the salt! Mosasaurs must have had salt glands, and I was first to propose a set of skull bones that may have housed such a gland in their head. This is work in progress, and can certainly benefit from student involvement!
MOSASAUR HIP
Tetrapods have three paired bones that make up the pelvis: ilia, pubes, and ischia. Whether quadrupedal or bipedal, the pelvis in limbed terrestrial tetrapods is connected to the spine via the first pair, i.e., the Ilia (you can feel the superior borders of your ilia when you place your hands on your hips). This hip-spine connection is lost in secondarily fully aquatic tetrapods, as is the case in whales today. In mosasaurs, scientists have long assumed that the ilia maintained the bony contact with the spine, typically with the very first tail vertebra. Based on this assumption, however, I noted that the waist of a 6-m-long mosasaur would become less than that of mine or most grown-ups, and that seemed highly unlikely! A mosasaur with such a constricted waist would experience a great deal of turbulence at their tail base when swimming, for we know that they had a deep, round chest anteriorly and a thick, muscular tail posteriorly. You can read the preliminary conclusion that I reached at in my 2012 SVP meeting abstract here, while I continue to find more data in support of the conclusion to this day. Please stay tuned!
FIGHT OR COURTSHIP?
Now is particularly an exciting time to study mosasaurs, as we continue to learn new aspects of their paleobiology, from their vision to food habits to underwater locomotion. Still, most of these aspects concern individual mosasaurs, i.e., what they did themselves and not with other mosasaurs. One exception to this would be mosasaur-on-mosasaur attacks postulated by many workers based on healed bite marks in various mosasaur specimens. There is a problem here though, where these bite marks could be made by animals other than mosasaurs. Thus, a researcher must be careful with jumping to the conclusion that mosasaurs fought with or killed each other in the absence of direct evidence. In 2012, a spectacular discovery was made in southern Alberta, Canada, by a mining company Korite International. The discovery of TMP 2012.010.0001, a 6.5-m-long mosasaur skeleton complete from the tip of the snout to that of the tail, came with a surprise: its left lower jaw had a healing puncture wound with a tooth from another mosasaur stuck in the center. Presented at an annual SVP meeting in 2016, we suggested that the tooth was from a conspecific--i.e., the same species as the one with the bite mark. The specimen represents the first direct evidence for non-lethal face biting between mosasaurs, a study featured in online news in Science. The followup study shows that healing legions are rather common in the jaws of many mosasaur taxa. If, as in TMP 2012.010.0001, most of these wounds were made by respective conspecifics, we must consider mosasaur mating, as well as combating, as the reason behind mosasaur face biting: both are known causes of intraspecific biting in living lizards and snakes.