Aquilolamna

Aquilolamna
Classification
Kingdom	Animalia
Phylum	Chordata
Class	Chondrichthyes
Subclass	Elasmobranchii
Superorder	Selachimorpha
Order	Lamniformes
Family	Aquilolamnidae
Genus	Aquilolamna
1st Species	Aquilolamna milarcae
Other Attributes
Time Range	94-92 mya
Location	Mexico
Name Meaning	Eagle shark
Physical Dimensions	1.7 meters long
Diet	Planktivore

Aquilolamna, informally known as the eagle shark, is an aquilolamnid mackerel shark from the Late Cretaceous of Mexico. It was named in 2021 by Romain Vullo and his associates. It was one of the strangest sharks to exist during the Cretaceous, due to its elongated pectoral fins; as well as this, its remains were housed in a private collection and purchased from a commercial dealer back in 2012, and they got increasing amounts of attention up until their publication 9 years later.

Physiology

Aquilolamna was an extremely bizzare shark. It had a long, slightly flattened, torpedo-shaped body, a noticeable lack of dorsal (back), pelvic ("leg"), and anal (rear) fins, and a large, broad head with a large, wide mouth. Perhaps the most defining trait of Aquilolamna was its long, wing-like pectoral fins, which spread out to a width greater than its body length. Its body would have been covered in scaly skin.

Diet

Aquilolamna was a planktivore, sucking up colonies of plankton. Its large, toothless mouth would have been used to filter plankton from the water.

Ecology

Aquilolamna's broad head, wide mouth, and wing-shaped pectoral fins may indicate that it was a suspension feeder, sucking in organic debris suspended in the water; in particular, it may have filled an ecospace similar to that of a manta ray, being an slow-moving filter feeder that swam in the epipelagic zone. However, unlike manta rays and like most other sharks, Aquilolamna still had a strong tail with a well-developed caudal fin; as well as this, its pectoral fins mainly served as stabilizers, although they could assist in underwater propulsion via slow flapping movements. Due to this, Aquilolamna likely swam through the water by a combination of lateral tail undulation (smooth, wavy movements) and pectoral fin oscillation (simple back-and-forth movements), with its tail providing the main thrust and its pectoral fins assisting in putting on bursts of speed or maneuvering. The only modern fishes to combine both methods of propulsion are guitarfishes and electric rays; however, their pectoral fins operate via undulatory movements similar to those of stingrays, whereas Aquilolamna's pectoral fins operated via simple oscillation. In general, sharks like Aquilolamna may have been among the more prominent filter-feeding animals in the Cretaceous seas, alongside large planktivorous pachycormids; both may have went extinct due to mass plankton death from ocean acidification.^[1]

References

1. Vullo, R., Frey, E., Ifrim, C., González, M. A. G., Stinnesbeck, E. S., & Stinnesbeck, W. (2021, March 19). Manta-like planktivorous sharks in Late Cretaceous oceans. Science. https://science.sciencemag.org/content/371/6535/1253.