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Jurassic Period Shark

An international team of paleontologists from Austria and Switzerland has uncovered an exceptionally well-preserved skeleton of Asteracanthus ornatissimus, a species of hybodontiform shark that lived about 150 million years ago (Jurassic period), in the famous limestones of Solnhofen in Germany.

Tentative life reconstruction of the hybodontiform shark Asteracanthus ornatissimus. Image credit: Sebastian Stumpf / Fabrizio De Rossi.

Tentative life reconstruction of the hybodontiform shark Asteracanthus ornatissimus. Image credit: Sebastian Stumpf / Fabrizio De Rossi.

Hybodontiform sharks are the closest relatives of modern sharks and rays,” said University of Vienna’s Dr. Sebastian Stumpf and colleagues.

“They first appeared in the latest Devonian, about 361 million years ago, survived two of the big five Phanerozoic mass extinction events, and finally became extinct at the end of the Cretaceous, about 66 million years ago.”

“These sharks had two dorsal fins, each supported by a prominent fin spine.”

“Their body size ranged from a few centimeters to approximately 3 m (10 feet) in maximum length, which consequently makes Asteracanthus one of the largest representatives of both its group and its time.”

“In contrast, modern sharks and rays, which were already diverse during the Jurassic, only reached a body size of up to 2 m (6.6 feet) in maximum length in very rare cases.”

Asteracanthus ornatissimus from the lower Tithonian of Solnhofen, Bavaria, Germany: (A) interpretative line drawing; (B) slab containing specimen; (C) close-up view of anterior dorsal fin spine; (D) close-up view of posterior dorsal fin spine; (E) tentative life reconstruction of female Asteracanthus ornatissimus. Abbreviations: adfs - anterior dorsal fin spine, af - anal fin, bv – basiventral, cf - caudal fin, ebr – epibranchial, lal - lateral line, Mc – Meckel’s cartilage, nc – neurocranium, notc – notochord, pcf - pectoral fin, pdfs - posterior dorsal fin spine, plr - pleural rib, pq – palatoquadrate, pvf - pelvic fin, scc - scapulacoracoid. Scale bars - 50 cm in (A, B) and 10 cm in (C, D). Image credit: Stumpf et al., doi: 10.1002/spp2.1350.

Asteracanthus ornatissimus from the lower Tithonian of Solnhofen, Bavaria, Germany: (A) interpretative line drawing; (B) slab containing specimen; (C) close-up view of anterior dorsal fin spine; (D) close-up view of posterior dorsal fin spine; (E) tentative life reconstruction of female Asteracanthus ornatissimus. Abbreviations: adfs – anterior dorsal fin spine, af – anal fin, bv – basiventral, cf – caudal fin, ebr – epibranchial, lal – lateral line, Mc – Meckel’s cartilage, nc – neurocranium, notc – notochord, pcf – pectoral fin, pdfs – posterior dorsal fin spine, plr – pleural rib, pq – palatoquadrate, pvf – pelvic fin, scc – scapulacoracoid. Scale bars – 50 cm in (A, B) and 10 cm in (C, D). Image credit: Stumpf et al., doi: 10.1002/spp2.1350.

In the new research, the paleontologists examined a new, exceptionally well-preserved skeleton of Asteracanthus ornatissimus with dentition and fin spines from the Solnhofen limestones.

Asteracanthus was scientifically described more than 180 years ago by the Swiss-American naturalist Louis Agassiz on the basis of isolated fossil dorsal fin spines,” they said.

“However, articulated skeletal remains have never been found — until now.”

According to the team, the dentition of Asteracanthus ornatissimus contained more than 150 teeth, each with a well-developed central cusp that was accompanied on both sides by several smaller cusplets.

“This specialized type of dentition suggests that Asteracanthus was an active predator feeding on a wide range of prey animals,” Dr. Stumpf said.

Asteracanthus was certainly not only one of the largest cartilaginous fishes of its time, but also one of the most impressive.”

The findings were published in the journal Papers in Palaeontology.

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Sebastian Stumpf et al. A unique hybodontiform skeleton provides novel insights into Mesozoic chondrichthyan life. Papers in Palaeontology, published online January 13, 2021; doi: 10.1002/spp2.1350

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