Top 10 Open Access Fossil Taxa of 2017: Eekaulostomus cuevasae | PLOS Paleo Community

This is an article I wrote for the PLOS Paleontology Community blog, and am archiving it here. The original post was published on December 28, 2017, and can be accessed here.

With the end of the year comes the end to our countdown of the winners of the Top 10 Open Access Fossil Taxa of 2017. We appreciate everyone that took the time to read all of the contenders this year and to vote in the contest!

At Number 1 is the armored trumpetfish Eekaulostomus cuevasae from the Paleocene of Chiapas, Mexico! Published in the Open Access journal Palaeontologia Electronica by authors Kleyton Magno Cantalice and Jesús Alvarado-Ortega, this unusual fish is related to modern-day trumpetfishes and represents the oldest-known representative of the acanthomorph fish superfamily Aulostomoidea.

Artistic rendition of Eekaulostomus cuevasae, art by Brian Engh (dontmesswithdinosaurs.com).

I asked the lead author of this study, Dr. Kleyton Magno a few questions about this remarkable fish. Dr. Magno is currently a postdoctoral researchers at the Universidad Nacional Autónoma de México (UNAM).

PLOS Paleo: Tell me about the discovery of this fossil!

KM: In reality, this species was collected by Mr. Alberto Montejo, a local quarry worker and owner of the Belisario Dominguez paleontological site. In the annual expedition to Chiapas in 2010, he gave this specimen to Drs. Jesús Alvarado and Martha Cuevas, as a donation to the Paleontological National Collection (housed into the Instituto de Geología, Universidad Nacional Autónoma de México). This single specimen was found just at the end of a hard fieldwork day, when a tropical storm was about to start. Then, Mr. Montejo noted a shining small part of this specimen on a place away from the work area, where the unwanted flagstones are accumulated; it was almost covered by the fallen leaves of the rainforest jungle in Chiapas. A desperate search was undertaken to find the counterpart of this specimen; however, the force of rain and the night denied such a possibility.

At first glance, Dr. Alvarado though that this fish was an extinct representative of the seahorses or pipefishes due the armored trunk. He was ready to prepare and describe this fossil when I entered the scene. My involvement in this discovery began in 2016, when I joined the Instituto de Geología of Universidad Nacional Autónoma de México as postdoctoral researcher. The aim of my work is to describe the spiny fishes of different Mexican localities, manly those from the Paleocene outcrops near Palenque City. When I first saw this specimen I immediately identified some characteristics that could resemble a syngnathid, however, by its body shape and configuration of the unpaired fins it seemed more likely to be a  member of the group that includes cornetfishes and trumpetfishes (Superfamily Aulostomoidea). During this study, we began to discover the remarkable features of this fish, some of them never been seen in this group, such as two stout, paired spines on the dorsal and anal fins, few soft rays on fins, and the body and snout covered by rigid star-like scales.

As we went deeper into the study I felt very excited; this was my fist fossil fish described, and it was already revealing itself to be an important clue to understanding the natural history of the aulostomoids, as it extends the fossil record of the group up to the Paleocene. Extant aulostomoids members are easily distinguished from their relatives (i.e., shrimpfishes, pipefishes, and seahorses) by the absence of rigid dermal scutes on the external surface of the body, as well as other features, such as a long body with parallel dorsal and anal fins, and a somewhat deep caudal peduncle. However, our aulostomid fossil was entirely covered with stout scutes. The inclusion the new species Eekaulostomus cuevasae in a morphological phylogenetic analysis, previously proposed by Keivany and Nelson (2006) for extant groups corroborates our hypothesis that this species is the oldest member of the Superfamily Aulostomoidea. This evidence and the comparison of E. cuevasae with other fossil aulostomoid allow us to infer new insights about the evolutionary history of the Superfamily Aulostomoidea.

Eekaulostomus cuevasae, holotype specimen and reconstruction. From Magno and Alvarado-Ortega (2017)

What does this fish tell us about the evolutionary history of Aulostomoidea?

Firstly, the Paleocene age of Eekaulostomus cuevasae represent an increment around 15 Ma on the origin and early diversification of aulostomoids, since the oldest forms were found in the middle Eocene of Europe (Pesciara of Monte Bolca, Italy). Furthermore, its geographical position is the first evidence of the Caribbean origin of aulostomoids with posterior diversification and currently worldwide distribution on tropical seas that still needs to better understood.

Eekaulostomus cuevasae is in the stem-group of aulostomoids. This allow us to say that the loss of dermal scutes, as well as stretching and tapering body, and the increment in the numbers of dorsal and anal soft rays are important morphological changes through the aulostomoid evolutionary history. We believed that these changes are morphological improvements on locomotion, buoyancy and adaptations to peculiar predatory behaviors present on extant aulostomoid species. The living species Aulostomus chinensis, for example, has the strategy to make reverse movements or maintain its body statically on the horizontal position, camouflaging between corals to opportunistically catch the prey.

What was the habitat and lifestyle of these fish? With their unusual heads, what did they feed on?

Unfortunately, little can be inferred about the habitat and lifestyle of this fish. Other fossils from the same locality of Eekaulostomus cuevasae are crabs, coprolites, fragments of turtles, carbonized plants, and a singular fauna of fishes that indicates a marine environment with some freshwater influence; however, more details about the paleoenvironment are still required. For now, what we can say is that E. cuevasae probably was a bad swimming, marine species that lived on marine shallow water, feeding on some crustaceans and small fishes using the peculiar method of prey suction through its feeding apparatus composed by small jaws and extreme elongated snout, like as in living aulostomoids forms.

The scales/scutes if this fish are really bizarre, and don’t look like fish scales at all! How did you recognize what you had? Do any other fish have scales like these?

As I mentioned previously, although living aulostomoid species do not have rigid body coverage, all close relatives have them. Nevertheless, the body coverage on these groups are composed of parallels bony plates that are quite distinct from the star-like scutes present on Eekaulostomuscuevasae. Its generic name is based on the shape of the scutes on this species. The prefix “Eek”, is a Mayan word that means “star” and, together with the word “aulos” (a kind if flute in Greek) and “stoma” (mouth in Latin) composes Eekaulostomus, in reference to a flute mouth fish with star-like scales.

The scutes of Eekaulostomus.

Anything else you’d like to share with us about this fish?

We decided to honor our colleague Dr. Martha Cuevas Garcia naming this fish as Eekaulostomuscuevasae because of her initial impulse that allowed us to perform several of the paleontological projects that are currently developing in Chiapas. Although she is an archaeologist who has spent years of work on different archaeological themes related to the Palenque Maya site, after work together in the paleontological prospection works in the southeastern part of Mexico, now she claims her love for fossils.

Congratulations to the UNAM team on this fantastic discovery of this fantastic fish Eekaulostomus and being chosen as the #1 Open Access Fossil Taxa of 2017!

Reference:

Cantalice KM and Alvarado-Ortega J (2017) Eekaulostomus cuevasae gen. and sp. nov., an ancient armored trumpetfish (Aulostomoidea) from Danian (Paleocene) marine deposits of Belisario Domínguez, Chiapas, southeastern Mexico. Palaeontologia Electronica 19.3.53A: 1-24.
 doi:10.26879/682

Keivany Y and Nelson JS (2006) Interrelationships of Gasterosteiformes (Actinopterygii, Percomorpha). Journal of Ichthyology, 46:S84–S96.

 

Top 10 Open Access Fossil Taxa of 2017: Websteroprion armstrongi | PLOS Paleo Community

This is an article I wrote for the PLOS Paleontology Community blog, and am archiving it here. I was originally published on December 5, 2017. You can see the original post here.

We listened to your feedback from last year’s Top 10 OA Fossil Vertebrates contest, and we agreed. Non-vertebrates needed representation, too! So of the 45 nominees we included in the contest this year, 1/3rd represented various plants, algae, insects, crustaceans, etc.

And as we continue the countdown of the winners of the PLOS Paleontology Top 10 Open Access Fossil Taxa of 2017, I am pleased to feature our first representative of an invertebrate taxon. Coming in at #8 is the fossil bobbit worm Websteroprion armstrongi, from the Devonian Kwataboahegan Formation of Ontario Canada. Described by authors Mats Eriksson, Luke Parry, and Dave Rudkin and published in the Open Access journal Scientific ReportsWebsteroprion represents the oldest bobbit worm (about 400 million years old), and a giant bobbit worm at that!

An artistic reconstruction of Websteroprion amrstrongi attacking an acanthodian fish. Art by James Ormiston.

Now if you are unfamiliar with bobbit worms, then you are in for a terrifying treat. These unusual polychaete worms are still living today and are vicious predators, laying in wait buried in the ocean sediment, their jaws poised like a bear trap, springing to life the minute a hapless fish swims idly by, only to be sucked into the sediment, becoming a meal for an unusual creature. Just watch this video below, courtesy the Smithsonian Channel on Youtube, to see a living bobbit worm in action.

These organisms are mostly soft-bodied, with the exception of their mouthparts, known as scolerodonts. So in the fossil record, often only the scolerodonts are preserved, and they usually aren’t that big. It was the size of the scolerodonts of Websteroprion that caught the eye of the authors. Mats Eriksson, lead author on the study, described to me the discovery of the specimens in the collection of the Royal Ontario Museum (ROM):

“Luke Parry [second author and then a PhD student at the University of Bristol, UK] was doing guest research on full-body polychaete fossils at the ROM back in 2014, and Dave Rudkin [third author on this study and now-retired museum curator at the ROM] showed him the specimens. So, Luke took a quick photograph and sent it to me, knowing that I am an expert on this fossil group.”

Scolerodont fossil impressions of Websteroprion armstrongi. Courtesy Luke Parry Twitter.

Dr. Eriksson continues, “I was quite disappointed when I first laid eyes on the photographs. The state of preservation was far from exceptional and mainly representing negative casts, or imprints, in the rocks. At first I even concluded that it was not worthwhile pursuing since it was ‘just another’ new species without any exciting story to unveil. That is until I asked about the size! Since the original image did not come with a scale bar I had simply assumed that the specimen was of “standard” millimetre size. I did ask Luke, who said that they were in fact pretty big, and provided the scale. That is when I strongly suspected that these must be by far the largest fossil jaws ever reported in the published literature, and a hunch which subsequent research confirmed. Now, this certainly wet my wormy appetite!”

Websteroprion armstrongi CT-scanning reconstructions of scolerodonts in specimen  ROM 63120. Modified from Eriksson et al (2017). CC-BY.

For bobbit worms, these are pretty massive, and for a polychaete worm in the Devonian, even more impressive. With the jaws wide open, they would have spanned about 2 cm across. The body, though not preserved, is estimated by the authors to be over 1 m (3 feet) in length, compared to the body proportions of extant bobbit worms. “I would not say they are necessary bigger than the jaws of extant bobbit worms,” Dr. Eriksson explains to me, “but it was surprising to find such large specimens in 400 million-year-old rocks!”

As Eriksson explains further, “Gigantism in animals is an alluring and ecologically important trait, usually associated with advantages and competitive dominance. It is, however, a poorly understood phenomenon among marine worms and has never before been demonstrated in deep time based on fossil material in this group of animals. The new species demonstrates a unique case of polychaete gigantism in the Palaeozoic, some 400 million years ago.

“Our study also shows that gigantism in jaw-bearing polychaetes was restricted to one particular evolutionary branch within the Eunicida, but has evolved many times in different species in this order of worms. However, while representing an ancient ‘Bobbit worm’ and a case of primordial eunicidan worm gigantism, the specific driving mechanism/s for W. armstrongi to reach such a size remains ambiguous.”

Would Websteroprion have been an ambush predator like its modern-day relatives? “We have little (in fact no) empirical evidence of its diet,” Dr. Eriksson explains. “As we are lacking soft parts we do not have access to preserved gut contents. And there are no coprolites found that can be directly linked to the animal. Inferring the diet of extinct worms (even jaw-bearing ones) is difficult. Especially considering that there are jaw-bearing extant forms that, despite looking like ‘fierce’ carnivorous predators, have proven to have a wide range of feeding habits. With that being said, given its size and compared to its closest modern relatives, I would assume that W. armstrongi had a similar mode of life and feeding habit as the modern bobbit worms. So, perhaps the Devonian fish and cephalopods were not safe from this critter.”

As mentioned previously, Websteroprion specimens caught the eyes of the authors in the collection of the ROM, but were actually collected over 20 years ago.

“The fossil specimens were collected over the course of a few hours in a single day in June 1994, when Derek K. Armstrong of the Ontario Geological Survey was dropped by helicopter to investigate the rocks and fossils at a remote and temporary exposure in Ontario,” Eriksson explains. “Sample materials, from what proved to belong to the Devonian so-called Kwataboahegan Formation, were brought back to the Royal Ontario Museum in Toronto, Canada, where they were stored until they caught the eyes of us authors.”

He adds, “Our study is an excellent example of the importance of looking in remote and unexplored areas for finding new exciting things, but also the importance of scrutinising museum collections for overlooked gems.”

And Websteroprion being a large and possibly terrifying creature wasn’t badass enough, it has a pretty stellar namesake as well. Lead author Mats Eriksson, in addition to being a professor at Lund University, moonlights as a Metal musician, complete with a paleo metal band Primoridal Rigor Mortis. In naming Websteroprion, Eriksson chose to honor a fellow metal musician, Alex Webster, bassist for Cannibal Corpse. And in true Metal fashion, Eriksson recently commissioned an iconic painter for Metal albums, Joe Petagno, to fashion Websteroprion in a dark and fantastical scene worthy of a album cover. The art, which can be seen here, will be part of an upcoming exhibition, Rock Fossils, which will be in Luxembourg in June 2018.

Congratulations to Websteroprion and the team that described it for making the PLOS Paleo Top 10 OA Fossil Taxa of 2017

Reference:

Eriksson ME, Parry LA, Rudkin DM (2017) Earth’s oldest ‘Bobbit worm’ – gigantism in a Devonian eunicidan polychaete. Scientific Reports 7:43061. DOI: 10.1038/srep43061

Source: Top 10 Open Access Fossil Taxa of 2017: Websteroprion armstrongi | PLOS Paleo Community

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