In these uncertain times, we can always fall back on the security of bones and knowing that they can preserve messages in the fossil record. By contrast, lesser tissues and even completely boneless organisms, including viruses, do not stand the test of geologic time particularly well, if at all. (Take that, novel coronavirus!).
So today it is particularly fitting to summarize a report emanating recently from the Wuhan Centre of China Geological Survey. The basis of the study is a strange marine reptile named Eretmorhipis, which comes from the Greek words for oar and fan. Two rather intact specimens have been discovered in Hubei Province, not far from Wuhan, in what was a lagoon 250 million years ago. This was a short two million years after a mass extinction wiped out 96% of marine animals.
Oar-fan is a suitable name for this lagoon dweller because the animal’s paddle-like feet with fanned-out digits were likely useful for propulsion and maneuvering. Eretmorhipis also sported ten dorsal triangular plates, reminiscent of the spinal blades of Stegosaurus.
Based on Oar-fan’s closely spaced vertebrae, thick ribs, and the presence of abdominal ribs, the investigators surmise that it did not have much trunk or tail flexibility, contrasted to most reptiles. What is even more remarkable is Oar-fan’s tiny head compared to its overall length of about three feet. The investigators note that only tiny eyes can fit in such a small head. They therefore surmise that Oar-fan did not see well, especially in murky water characteristic of lagoons. So it had to rely on another sense to capture prey. But in its small head there would not be room for much sound detection equipment either. And everybody knows that trying to smell under water doesn’t work. How about tasting, since tongue flicking is a well-known reptilian trait? The investigators discount that sense as useful for Oar-fan to go hunting because “the vomeronasal fenestra is lacking in the palate … and tongue flicking is unsuitable for prey and predator detection.” I’ll have to take their word for those facts.
So with a clumsy trunk and tail, lousy eyes and ears, and the unlikely ability to taste or smell, how did Oar-fan catch food? The investigators took a second look at Oar-fan’s jaw, which is shaped like a duck’s bill, and the lights went on. The whole animal is as preposterous as a duckbilled platypus, and its snout is the same shape. A platypus is known to scavenge in murky water by snatching up whatever its bill bumps into; and Oar-fan probably did the same, with shrimp being its most likely dietary staple. Another possibility, which the investigators cannot rule out based on the fossil record, is that Oar-fan used electroreception. This works for Guiana dolphins but is not known to exist in reptiles; and even bones, as great as they are for preserving Earth’s history, cannot provide that answer.
Oar-fan does, however, add useful insights into the rapid ecological diversification that occurred after a monumental mass extinction. Furthermore, thank you, Oar-fan, for momentarily diverting our attention from pandemics. Any good news from Wuhan is good news indeed.