Aquilolamna

Credit: Oscar Sanisidro.

*Aquilolamna*, or the eagle shark, is an extinct genus of "mackerel" shark that lived in Mexico during the Late Cretaceous.

## History

*Aquilolamna* was named from a single well-preserved specimen recovered in 2012 by an unnamed quarry worker in Vallecillo, from the Mexican state of Neuvo León. The specimen came to Margarito González González, local paleontologist and lead author. It was cleaned and prepared by him, gaining more recognition in paleontological conferences until description in 2021. However, the paper states the specimen was recovered from the black market, and checked to make sure it was valid. The head author of the paper, González González, upon further investigation, seems to be a fabricated name. Additionally, co-author Eberhard "Dino" Frey is listed, who is known to have illegally transported fossils from Brazil and other areas, such as in the "Ubirajara" case. Because of this, Aquilolamna is a very likely case of unethical fossil description with use of a pseudonym.

## Description

*Aquilolamna* sports a body that is unknown in every living or extinct shark. They had a torpedo-shaped body, like most sharks, with pectoral fins that make the body wider than it was long. Along with it's broad head, the authors speculate *Aquilolamna* was a planktivorous filter-feeder convergently evolved to be like manta rays. However, the latter appears much later in the fossil record, and unlike rays that "fly" underwater, *Aquilolamna* likely glided along akin to basking sharks and other planktivores. It's body was propelled by the tail fin, as it seems the other fins are not present on *Aquilolamna*. Classification *Aquilolamna* was described as an elasmobranch, but this classification may not be reliable due to no preserved teeth in the holotype, which are crucial when classifying extinct sharks. They may have dislodged when the individual died, or they are in deeper matrix in the same locality. Possible skin impressions may be bacterial mats. The naming paper, published in 2021, tentatively assigned the shark into lamniformes based on a few morphological similarities. However, some think the shark belongs to other affinities, in-which more research is required. However, some have proposed an affiliation with *Cretomanta*, an unknown neoselachian, which may have belonged in the same family as, the newly-erected aquilolamnidae, as it lived around the same time as *Aquilolamna*.

## Paleoecology

*Aquilolamna* lived in the pelagic waters of Turonian Mexico, 93 million years ago. The Agua Nueva Formation of which it was found is though to be comprised of sediments deposited on the outer shallow continental shelf. It may have lived alongside marine reptiles, ammonites, and bony fishes such as *Vallecillichthys*, *Goulmimichthys* and *Araripichthys*. The large mackerel shark *Cretoxyrhina* was the apex predator. *Aquilolamna* and it's lineage may have went extinct due to a decline in plankton populations due to the K-PG's ocean acidification. Later, mobulid rays and batoids likely filled the empty niche left by *Aquilolamna*.

## References

* https://science.sciencemag.org/content/371/6535/1253
* https://phys.org/news/2021-03-discovery-winged-shark-cretaceous-seas.html
* https://www.nationalgeographic.com/science/article/shark-like-fossil-with-manta-wings-is-unlike-anything-seen-before
* https://www.abc.net.au/news/science/2021-03-19/long-winged-shark-aquilolamna-cretaceous-fossil-palaeontology/100014976
* https://www.reuters.com/article/us-science-shark-idUSKBN2BA2J4
* https://www.wionews.com/science/fossils-of-bizarre-shark-with-wing-like-fins-from-93-million-years-ago-found-in-mexico-371859
* http://www.sci-news.com/paleontology/aquilolamna-milarcae-09470.html
* https://www.sciencedirect.com/science/article/pii/S1631068303000642