Top 10 Open Access Fossil Taxa of 2017: Babelichthys olneyi

Our readers have spoken, and the Top 10 Open Access Fossil Taxa of 2017 have been selected. To celebrate each individual taxon and study, the editors of PLOS Paleo will highlight each in its own individual blog post, counting down from #10 to the number #1 winner.

At #10, I present Babelichthys olneyi, described and published in the open access journal PeerJ by Donald Davesne, a postdoctoral researcher at the University of Oxford. It is named after the Babelfish from Douglas Adams’ The Hitchhiker’s Guide to the Galaxy, and though this intriguing specimen might not be a polyglot, it still offers up some unique insight into the history of crestfishes.

Babelichthys, based on a single specimen, was recovered from the Middle-Late Eocene Zagros Basin in Iran. It is the first and only-known fossil unicorn crestfish. Crestfishes, in the family Lophotidae, are deep-sea teleosts that are visually notable by their pronounced cranial crests, hence the name. With only two living species and four extinct species, crestfishes are a small but striking group. You might be more familiar with the closely related oarfishes of the family Regalecidae, which often wash ashore and make for many historic sea serpent tales. Or you might recognize the opah, whose genus name Lampris is the base for the Order Lampriformes despite it bearing zero resemblance to most of the fishes in this order (the opah being round and deep-bodied, and most lampriformes being long and ribbon-like).

Babelichthys clearly resembles other living crestfishes with its pronounced head. But for decades it had mistakenly been identified as a specimen of another crestfish species Protolophotus. It took Dr. Davesne to recognize the unique attributes that set Babelichthys apart from other lophotids and properly designate it as a new species.

I was able to ask Dr. Davesne about his work on this fabulous fishy find!

PLOS Paleo: This specimen was collected a long time ago! Why did they go unnoticed as a new taxon for so long? Tell me about your process “discovering” this new species.

The specimen was indeed collected in the 1930s and assigned to another genus, Protolophotus [pictured above]. Another author later recognized that is was distinct and created a new name, but it was invalid because no description was provided. I had noticed the specimen during my Ph.D. at the MNHN in Paris (it was in the public exhibition), but didn’t know about this problem. It wasn’t until my postdoc, during a visit in Moscow to study fossil lampridiforms from Russia that my colleague Alex Bannikov made me realize this taxon needed a new name and a proper description.

The Babelfish is a popular creature in the sci-fi universe. Why did you choose to honor it?

I read the Douglas Adams books a long time ago, and since it is one of the few “fish-related” famous sci-fi references, I had the idea to name a species after it early in my PhD on spiny-rayed fishes. So when I decided to describe and give a name to this very weird-looking animal, I knew it should be Babelichthys!

What do you think is the function/purpose of the pronounce crest on the skull of Babelichthys?

Hard to know! The modern relatives of this animal live in the deep water and are almost never observed alive! We don’t know much about their feeding ecology, for example.

This is the first known fossil unicorn crestfish. What does this fossil tell us about the evolution of lophotid fishes?

It shows that this family was already diverse in the early Cenozoic, with relatives to both modern genera now described in the fossil record. More broadly, it helps understanding the timeframe of lampridiform evolution. Our previous research found that the Late Cretaceous ancestors of these animals probably looked like your regular teleost, with a rounded and laterally flattened body. Between the end of the Cretaceous and the middle Eocene, they acquired this series of derived character states that make them so peculiar today, with their very elongate body and weird crests on the head. This suggests that their rate of morphological evolution was quite rapid in the early Cenozoic, but has slowed since then.

 What would have been the habitat or lifestyle of this fish?

Modern crestfishes (and most lampridiforms) live in the mesopelagic environment, between 200 and 1000 m in depth, and spend most of their lives in the water column. We can assume that this was also the case of Babelichthys. Actually, other fossil teleosts found in the same locality in Iran (and also kept in the Paris museum) also belong to taxa that live in this kind of environment today, like hatchetfishes and deep sea cods. It is one of the few potential examples of a mesopelagic fauna that we have in the teleost fossil record.

Do you have any other insight about this organism/discovery that you want to share with the world? Any other thoughts you’d like to add?

I would like to thank you for organizing this contest that showcases open access taxonomic paleo papers. Online open access journals like PeerJ are actually pretty great because they don’t have strict guidelines in term of length or scope, which means that they’re susceptible to accept this kind of very descriptive manuscript that other kinds of journals might deem too ‘boring’. But we still need to publish taxonomical descriptions from time to time, especially in paleoichthyology, where so many awesome specimens are just there in the collections without anyone studying them. I’m also glad that another paper on fossil teleosts won first prize!

Reference:

Davesne D (2017) A fossil unicorn crestfish (Teleostei, Lampridiformes, Lophotidae) from the Eocene of Iran. PeerJ 5:e3381 https://doi.org/10.7717/peerj.3381