If looks could kill and not teeth, then this ichthyosaur would have been dangerous. As this is not true, with its large eyes and tiny teeth, this ichthyosaur appears kind of cute—hence its nickname, “Mascot.” However, it has now been formally named Janusaurus lundi by Aubrey and her supervisors on the 1st of August (2014) in the scientific journal PLOS ONE.
By Aubrey Roberts and Victoria Engelschiøn Nash
Janusaurus lundi is one of the oldest ichthyosaurs the team has excavated from the Upper Jurassic (147-million years ago; Early Volgian). The specimen consists of a skull, shoulder, partial paddles and hip bones. It may not be the most beautiful or complete ichthyosaur in the world, but “Mascot” has a few very strange differences from other ichthyosaurs, such as a weird hip bone and braincase. Janusaurus lundi was named after the mountain on which it was found, “Janusfjellet”, and a volunteer on the project, Bjørn Lund.
The Schwarzenegger of the Jurassic Svalbard Seas
“Mascot” or Janusaurus lundi may be small, but it had massive shoulders for its size; a real broad-shouldered “Schwarzenegger” of the seas. Why were the shoulders so massive and robust? We don’t know, but maybe more specimens could yield an answer. Every new species described in science answers some questions, but tends to ask more.
The eyes, however, which are the size of a small dinner plate, were probably used to find prey in deep, dark water. Ichthyosaurs have the world record for vertebrates (animals with a backbone) in eye size compared to body size. Animals with large eyes can hold more photoreceptive cells than small eyes, which is why scientists believe large eyes are a good indicator that they had great vision.
A Prolonged Preparation
Aubrey, along with May-Liss Funke, the research technician at the museum, did most of the preparation of “Mascot”, which in total took about 2,000 hours and an entire year to finish. The skull in particular was very fragile and broken down to millimeter-size pieces as it was exposed on the surface. In fact, the team didn’t know the skull was there till we found it in the lab. When you look at the picture from the field (below), you can see that it is hard to see any skull at all.
The main plaster jacket including the shoulder, paddle and skull took the most time to prepare. We removed the shoulder bones and the paddle one by one, then decapitated the skull from the body. We prepped the skull from both sides and the entire left side (which was exposed on the surface) was eroded away. This gave an interesting view of the inside of the skull and lower jaw, which you don’t usually get. So in other words, loss is not necessarily a bad thing.
Family Trees for Ichthyosaurs
Janusaurus lundi is a member of a particular family of ichthyosaurs called “ophthalmosaurids.” This group of ichthyosaurs lasted from the Middle Jurassic to the Early Cretaceous, when ichthyosaurs became extinct. This family was spread worldwide during this time, and on Svalbard we have several different species. The two other species described are Palvennia hoybergeti and Cryopterygius kristiansenae. Janusaurus differs from these other species in a number of ways, but a family tree analysis (called a phylogenetic analysis) shows that the ophthalmosaurids on Svalbard are more related to each other than to any other species. That is interesting because it could suggest that the Svalbard ichthyosaurs were endemic, meaning that they were only found in that area.
The description of Janusaurus lundi was written by Aubrey as her Master of Science thesis at the University of Oslo.
So Long and Thanks for All the Fish
Well, now we are heading off to Svalbard to go and look for more ancient marine reptiles. We will have blog posts throughout the expedition, so keep following!