Plesiosaurs, pliosaurs, hybodonts: Looking again at three prehistoric predators of the Jurassic seas


The Liopleurodon was a pliosaur of the Jurassic interval. Credit: SciePro/Shutterstock

The fossilized stays of a huge ichthyosaur, colloquially generally known as a “sea dragon,” have been recently uncovered on the Rutland Water Nature Reserve within the UK. Measuring at the least ten meters in size and with a cranium weighing roughly one ton, it is the biggest, most full ichthyosaur of its variety discovered up to now in Britain.

The skeleton was found by Joe Davis of the Leicestershire and Rutland Wildlife Trust in February 2021. It was rigorously excavated in August and September 2021 by a crew of paleontologists assembled from across the UK (together with myself), led by ichthyosaur professional Dr. Dean Lomax and palaeontological conservator Nigel Larkin.

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Based on evaluation of microscopic fossils from the encompassing sediment, we have been capable of confirm that the Rutland ichthyosaur is roughly 181.5 to 182 million years outdated. The creature’s anatomy suggests it most probably belongs to the species Temnodontosaurus trigonodon. This would make it the primary prevalence of this ichthyosaur species within the U.Ok.

It’s a standard false impression that ichthyosaurs have been “swimming dinosaurs.” But they have been really a gaggle of marine reptiles which lived throughout the Mesozoic period (between 66 and 252 million years in the past). As successful major predators, they have been elementary to Mesozoic marine ecosystems.

The variety of ichthyosaur species peaked throughout the Triassic interval (between 250 and 201 million years in the past) and particularly the Jurassic interval (201 to 145 million years in the past). But these weren’t the one predators patrolling the prehistoric seas. Let’s dive in and have a look again at three different extinct sea creatures that dominated the Jurassic oceans.

Plesiosaurs, pliosaurs, hybodonts: looking back at three prehistoric predators of the Jurassic seas
A reconstruction of the Rutland ichthyosaur Temnodontosaurus trigonodon. Credit: Bob Nicholls, Author supplied


Plesiosaurs (that means “near to lizard”) have been a gaggle of enormous, long-necked marine reptiles that belong to the order Plesiosauria. These animals appeared within the Late Triassic period and have become particularly prevalent throughout the Jurassic interval. They thrived till their disappearance within the Cretaceous–Paleogene extinction event, roughly 66 million years in the past. Plesiosaurs existed in oceans internationally: in European seas and across the Pacific Ocean, together with Australia, North America and Asia.

Plesiosaurs ranged in length from lower than 2 meters to greater than 17 meters. Some species had extremely long necks, virtually twice so long as the remainder of their physique.

Plesiosaurs had a broad, flat physique, quick tail, and 4 lengthy fins which made this animal a powerful swimmer. They additionally had a small head—however they have been full of sharp, pointed tooth to facilitate their carnivorous weight loss plan of fish and historical squid-like molluscs. Like ichthyosaurs, plesiosaurs gave delivery to live young. The first almost-complete skeleton of Plesiosaurus was found in 1823 at Lyme Regis, Dorset within the UK by pioneering paleontologist Mary Anning.

Plesiosaurs, pliosaurs, hybodonts: looking back at three prehistoric predators of the Jurassic seas
The Plesiosaurus lived throughout the Jurassic interval. Credit: Warpaint/Shutterstock


Pliosaurs (that means “more lizard”) are one other group of Jurassic marine reptiles which belong to the order Plesiosauria. But not like their long-necked plesiosaur cousins, these animals had short necks with a big, elongated head just like crocodiles. Pliosaurs ranged from round 4 to 10 meters in size, however could possibly be up to 15 meters. Pliosaurs additionally had two pairs of highly effective paddles and a comparatively quick tail.

During sure elements of the Jurassic interval, they have been the highest predators of the ocean. The creature’s highly effective jaws contained sharp, conical tooth which they used to feed on fish, sharks, ichthyosaurs and different Plesiosauria.

This genus is represented by 4 species (R. cramptoni, R. propinquus, R. thorntoni and R. zetlandicus) and all at present recognized specimens have been found in Yorkshire and Northamptonshire within the UK. Like plesiosaurs, pliosaurs turned extinct within the Cretaceous–Paleogene extinction occasion 66 million years in the past.

Plesiosaurs, pliosaurs, hybodonts: looking back at three prehistoric predators of the Jurassic seas
A Hybodus fraasi fossil from Germany. Credit: Wikimedia commons, CC BY

Hybodont sharks

Hybodus (that means “humped tooth”) is an extinct genus of shark which first seems in direction of the top of the Permian interval (260 million years in the past). It turned extremely profitable within the shallow Jurassic seas, away from the deep waters that plesiosaurs and pliosaurs inhabited.

This genus possessed streamlined, fusiform our bodies (spindle-shaped, elongated and tapering at each ends) which enabled them to maneuver rapidly although the water. They additionally had two fins on their backs which might have helped them steer with precision. These opportunistic predators sometimes grew to roughly two meters lengthy.

Hybodus consumed all kinds of prey due to their tooth, which have been organized into two teams. At the entrance have been sharp, pointed tooth which have been helpful for grabbing prey together with fish and squid; whereas the again tooth have been rounded and extra fitted to crushing the shells of crustaceans.

In truth, a specimen of Hybodus belonging to the species H. hauffianus from Holzmaden in Germany was discovered filled with belemnites (extinct cephalopod molluscs), suggesting that this creature died after overindulging on too many belemnite rostra (shells).

The hybodonts became extinct in direction of the top of the Late Cretaceous interval, some 66 million years in the past. The first fossilized Hybodus tooth have been discovered within the UK across the mid-Nineteenth century, however stays together with skeletons, remoted tooth and head and fin spines have now been recovered from Asia, Europe, Africa and North America.

Extinct swordfish-shaped marine reptile discovered

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Plesiosaurs, pliosaurs, hybodonts: Looking again at three prehistoric predators of the Jurassic seas (2022, January 20)
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