Post by creature386 on Mar 30, 2021 3:11:31 GMT 5
Aquilolamna milarcae
Aquilolamna milarcae by Apokryltaros - Own work, CC BY-SA 4.0, commons.wikimedia.org/w/index.php?curid=101798609
Temporal range: Turonian (Late Cretaceous; 93 Ma)
Location: Agua Nueva Formation (Mexico)
Scientific classification:
Animalia
Chordata
Chondrichthyes
Lamniformes
Aquilolamna
A. milarcae
Description:
Aquilolamna milarcae was a species of Chondrichthyes (likely a lamniform) from the Late Cretaceous of Mexico. It is known from a well-preserved skeleton and possible skin impressions. The skeleton is about 1.65 m long.
This animal's most striking feature is its fin design. Its pectoral fins are large, broad, and slender like those of a manta ray, its wingspan approaching two meters. This contrasts with the short pectoral fins of modern sharks, likely the closest living relatives of Aquilolamna milarcae, which are designed to their streamlined owners' maximum maneuverability. The wing-like fins of A. milarcae likely enabled it to perform a type of slow underwater flight though, unlike modern manta rays, it had the additional option of powered-swimming with its fork-like tail fin.
Apart from its fins, A. milarcae is also notable for its lack of preserved teeth in its broad skull. This is notable since the teeth of fossil sharks are normally more likely to preserve than the rest of the skeleton. This, along with its likely slow swimming speed, is taken as evidence that it likely fed primarily on plankton, much like modern manta rays.
Phylogenetic position:
Aquilolamna milarcae has been assigned to Lamniformes based on its forked tail fin with a well developed upper lobe. It should be noted that this assignment is highly tentative due to its lack of preserved teeth. Teeth are highly important in shark classification, especially in prehistoric shark classifcation, thus, further data will be necessary for a more precise systematic classification.
Literature:
Vullo, R., Frey, E., Ifrim, C., González, M.A.G., Stinnesbeck, E.S., Stinnesbeck, W. Manta-like planktivorous sharks in Late Cretaceous oceans. Science. (2021) 371 (6535): 1253–1256. doi:10.1126/science.abc1490
Weblinks:
phys.org/news/2021-03-discovery-winged-shark-cretaceous-seas.html
Official description paper abstract available at Science (link).
Aquilolamna milarcae by Apokryltaros - Own work, CC BY-SA 4.0, commons.wikimedia.org/w/index.php?curid=101798609
Temporal range: Turonian (Late Cretaceous; 93 Ma)
Location: Agua Nueva Formation (Mexico)
Scientific classification:
Animalia
Chordata
Chondrichthyes
Lamniformes
Aquilolamna
A. milarcae
Description:
Aquilolamna milarcae was a species of Chondrichthyes (likely a lamniform) from the Late Cretaceous of Mexico. It is known from a well-preserved skeleton and possible skin impressions. The skeleton is about 1.65 m long.
This animal's most striking feature is its fin design. Its pectoral fins are large, broad, and slender like those of a manta ray, its wingspan approaching two meters. This contrasts with the short pectoral fins of modern sharks, likely the closest living relatives of Aquilolamna milarcae, which are designed to their streamlined owners' maximum maneuverability. The wing-like fins of A. milarcae likely enabled it to perform a type of slow underwater flight though, unlike modern manta rays, it had the additional option of powered-swimming with its fork-like tail fin.
Apart from its fins, A. milarcae is also notable for its lack of preserved teeth in its broad skull. This is notable since the teeth of fossil sharks are normally more likely to preserve than the rest of the skeleton. This, along with its likely slow swimming speed, is taken as evidence that it likely fed primarily on plankton, much like modern manta rays.
Phylogenetic position:
Aquilolamna milarcae has been assigned to Lamniformes based on its forked tail fin with a well developed upper lobe. It should be noted that this assignment is highly tentative due to its lack of preserved teeth. Teeth are highly important in shark classification, especially in prehistoric shark classifcation, thus, further data will be necessary for a more precise systematic classification.
Literature:
Vullo, R., Frey, E., Ifrim, C., González, M.A.G., Stinnesbeck, E.S., Stinnesbeck, W. Manta-like planktivorous sharks in Late Cretaceous oceans. Science. (2021) 371 (6535): 1253–1256. doi:10.1126/science.abc1490
Weblinks:
phys.org/news/2021-03-discovery-winged-shark-cretaceous-seas.html
A soaring shark
Modern sharks occupy marine ecosystems across the world but display little morphological diversity, being mostly streamlined predators. Vullo et al. describe a new species of shark from the late Cretaceous that shows that the lack of current variation is not due to limited morphological “exploration” in the past. Specifically, Aquilolamna milarcae displays many features similar to modern manta rays, notably long, slender fins and a mouth seemingly adapted to filter feeding, suggesting that it was planktivorous. This finding indicates both that elasmobranchs evolutionarily experimented with other forms and that the planktivorous “soarers” emerged in this group at least 30 million years earlier than previously recognized.
Abstract
The ecomorphological diversity of extinct elasmobranchs is incompletely known. Here, we describe Aquilolamna milarcae, a bizarre probable planktivorous shark from early Late Cretaceous open marine deposits in Mexico. Aquilolamna, tentatively assigned to Lamniformes, is characterized by hypertrophied, slender pectoral fins. This previously unknown body plan represents an unexpected evolutionary experimentation with underwater flight among sharks, more than 30 million years before the rise of manta and devil rays (Mobulidae), and shows that winglike pectoral fins have evolved independently in two distantly related clades of filter-feeding elasmobranchs. This newly described group of highly specialized long-winged sharks (Aquilolamnidae) displays an aquilopelagic-like ecomorphotype and may have occupied, in late Mesozoic seas, the ecological niche filled by mobulids and other batoids after the Cretaceous–Paleogene boundary.
Modern sharks occupy marine ecosystems across the world but display little morphological diversity, being mostly streamlined predators. Vullo et al. describe a new species of shark from the late Cretaceous that shows that the lack of current variation is not due to limited morphological “exploration” in the past. Specifically, Aquilolamna milarcae displays many features similar to modern manta rays, notably long, slender fins and a mouth seemingly adapted to filter feeding, suggesting that it was planktivorous. This finding indicates both that elasmobranchs evolutionarily experimented with other forms and that the planktivorous “soarers” emerged in this group at least 30 million years earlier than previously recognized.
Abstract
The ecomorphological diversity of extinct elasmobranchs is incompletely known. Here, we describe Aquilolamna milarcae, a bizarre probable planktivorous shark from early Late Cretaceous open marine deposits in Mexico. Aquilolamna, tentatively assigned to Lamniformes, is characterized by hypertrophied, slender pectoral fins. This previously unknown body plan represents an unexpected evolutionary experimentation with underwater flight among sharks, more than 30 million years before the rise of manta and devil rays (Mobulidae), and shows that winglike pectoral fins have evolved independently in two distantly related clades of filter-feeding elasmobranchs. This newly described group of highly specialized long-winged sharks (Aquilolamnidae) displays an aquilopelagic-like ecomorphotype and may have occupied, in late Mesozoic seas, the ecological niche filled by mobulids and other batoids after the Cretaceous–Paleogene boundary.