The ichthyosaur(s) with 4 nostrils: Musicasaurus

Maxwell et al. 2015
described a juvenile ophthalmosaur, Muiscasaurus catheti, from the Early Cretaceous of Columbia, and it had a bony process dividing its naris. Online press (BBC.com) described the specimen as having four nostrils (Fig. 1). It does not really have four nostrils, but wait, there’s more…

Figure 1. Muiscasaurus catheti prior to final prep, final prep and diagram. Naris is highlighted.

Figure 1. Muiscasaurus catheti prior to final prep, final prep and diagram. Naris is highlighted.. Compare to Ophthalmosaurus natans in figure 2.

The BBC site reported, 
“The fossil is of an infant only about 3m long. Adults may have reached 5m.” Maybe it is best described as “immature” or a “juvenile” when it is more than half the adult size. It is certainly not an infant.

“I could tell it was a juvenile based on the size of its eyes relative to the rest of the skull,” says author Erin Maxwell of the Natural History Museum in Stuttgart, Germany. “In reptiles, babies have very big eyes and heads compared to their body.”

Of course
adult ichthyosaurs with exceptionally large eyes, like Ophthalmosaurus (Fig. 2) have been known for over a century. Perhaps Dr. Maxwell was misquoted. That happens. Also when we look at Ophthalmosaurus, it has nearly the same naris shape as seen in Muiscasaurus catheter. 

Figure 2. Two variations on Ophthalmosaurus, both with large eyes and one with a peanut-shaped naris, similar to the four-nostril Muiscasaurus.

Figure 2. Two variations on Ophthalmosaurus, both with large eyes and one with a peanut-shaped naris, similar to the four-nostril Muiscasaurus.

Another news source,
the Ulyanovsk Chronicles, recently published a story and image of another “ichthyosaur with four nostrils,” (Fig. 3) from the Aptian (Early Cretaceous, 120 mya) of Sengileevsky paleontological reserve. The site reported [after Google translation], “A preliminary study of a new Museum exhibit conducted by Valentin Fischer (University of Liege, Belgium), [AND] Maxim Arkhangelsky (Saratov state technical University) showed that he loved aikataulu [referred the specimen to?] (Muiscasaurus).” 

Figure 3. A Russian four-nostril ichthyosaur with the pencil resting in the posterior naris.

Figure 3. A Russian four-nostril ichthyosaur with the pencil resting in the posterior naris.

In this new specimen
the anterior and posterior portions of the naris are more completely divided. I wonder if all ichthyosaurs had such a dual naris in soft tissue, but only in these specimens can we find bony support?

References
Maxwell EE, Dick D, Padilla S and Parra ML 2015. A new ophthalmosaurid ichthyosaur from the Early Cretaceous of Columbia. Papers in Palaeontology 2015:1-12.

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