Categories
monster' munch

Monster munch: Ancient marine reptile died after dining on fellow titan – Yahoo News

More than 230 million years ago, a giant, dolphin-like marine reptile known as an ichthyosaur devoured its final meal — a creature almost its own size — then died a short time later.

Inside its belly was the body of a lizard-like aquatic reptile called a thalattosaur, shorn of its head and long tail but undigested.

Paleontologists digging in a quarry in southwestern China were surprised to discover the remains in 2010: it’s almost unheard of to find the stomach contents of marine fossils.

A decade on, in a paper published in iScience Thursday, researchers concluded that rather than feeding on much smaller cephalopods like squid, the five-meter (16-foot) long ichthyosaur was probably a megapredator.

What’s more, this particular specimen might have died while ingesting its prey, literally biting off more than it could chew.

“The most likely cause of death is the neck breakage, which likely prevented the predator from breathing,” co-author Ryosuke Motani, a paleobiologist at the University of California, Davis told AFP.

The ichthyosaur may have sustained injuries while fighting the thalattosaur, he added, or while trying to swallow it — or both.

But, Motani cautioned: “The interpretation of the death process involves speculation, because nobody was there filming it for us.” 


– Crocodile-like teeth – 

The team are a bit more confident that the thalattosaur, which was slightly smaller than its foe at four meters in length, met a violent end, rather than being scavenged after dying of natural causes.

“There are no signs of rotting of the prey — if it was a rotten carcass, you would not expect to see the fingers still attached to the body,” said Motani.

The thalattosaur’s disconnected tail was found 20 meters (65 feet) away, leading the team to believe it was ripped off and left behind by the ichthyosaur.

The ichthyosaur’s stomach contents didn’t show signs of advanced digestion by acid, meaning it likely perished soon after its final meal.

“At first, we just didn’t believe it, but after spending several years visiting the dig site and looking at the same specimens, we finally were able to swallow what we were seeing,” added Motani.

Because the discovery of stomach contents in marine fossils is so rare, scientists generally rely on tooth and jaw shapes to discern what they may have eaten.

Ancient apex predators are typically thought to have had large, very sharp teeth — even though some modern predators like crocodiles use blunt teeth to consume large prey using grasping force instead of cutting.

Ichthyosaurs have blunt teeth, but because there was no direct evidence of large prey consumption, researchers previously thought they must feed on small prey.

“Now, we can seriously consider that (Ichthyosaurs) were eating big animals, even when they had grasping teeth,” added Motani.

These events took place after the end of the Permian period, some 250 million years ago, when land vertebrates started moving back to the sea following a mass extinction event.

The fact that predators arose shortly afterwards in the Middle Triassic was a sign that ecosystems were bouncing back, said Motani.

ia/ft

Read More

Categories
monster' River

‘River monster’ first-known dinosaur to have lived in water – BBC Focus Magazine

The newly-discovered tail fossil of the first “river monster” dinosaur shows the giant predator was a powerful swimmer and the first known to have lived in the water.

The six-tonne Spinosaurus aegyptiacus prowled the rivers that flowed through the Sahara desert 100 million years ago, living and catching its prey in the water, according to the new research.

The study on the tail, which was unearthed in southern Morocco, was carried out by an international team including from the universities of Portsmouth and Leicester, and supported by a grant from the National Geographic Society.

'River monster' first-known dinosaur to have lived in water (Reconstruction of Spinosaurus in life © Davide Bonadonna/PA)
Reconstruction of Spinosaurus in life © Davide Bonadonna/PA

The University of Portsmouth said: “Until now it was believed that dinosaurs lived exclusively on land, but the newly discovered tail of Spinosaurus aegyptiacus, a giant predator, shows that it was actually well adapted to an aquatic lifestyle.

“The 15-metre-long, six-tonne predator was, in fact, a powerful swimmer propelled by a huge fin-like tail, which hunted down its prey in vast river systems that flowed through the Sahara desert 100 million years ago.

“It is the first time that such an adaptation has been reported in a dinosaur.”

Top: reconstruction of the tail skeleton of Spinosaurus (missing bones shown in white). Centre: cross sections through the tail showing changes in the vertebrae, tail volume, and arrangement of major muscles. Bottom: the new, surprising look of Spinosaurus (black, soft parts; red, bones collected by the locals; green, bones from recent scientific excavations; yellow, bone fragments collected in the debris). Drawings: Marco Auditore. (Gabriele Bindellini/PA)
Reconstruction of the  Spinosaurus tail skeleton (missing bones shown in white), cross sections through the tail and a complete view of Spinosaurus © Marco Auditore/Gabriele Bindellini/PA

Dr David Unwin, reader in palaeobiology at the University of Leicester, said: “The Spinosaurus’ fin-like tail is a game-changing discovery for us that fundamentally alters our understanding of how this dinosaur lived and hunted – it was actually a ‘river-monster’.

“As well as its tail, many other features of this dinosaur, such as the high position of the nostrils, heavy bones, short legs, and paddle-like feet point to a life spent in the water rather than on land.

“Not only did dinosaurs dominate the land and take to the air as birds, they even went back into the water and became the top predators there as well.”

'River monster' first known dinosaur to have lived in water (Two Spinosaurus hunt Onchopristis, a prehistoric sawfish, in the waters of the Kem Kem river system in what is now Morocco © Jason Treat, NG Staff, and Mesa Schumacher Art: Davide Bonadonna Source: Dr. Nizar Ibrahim, University of Detroit Mercy)
Two Spinosaurus hunt Onchopristis, a prehistoric sawfish, in the waters of the Kem Kem river system in what is now Morocco © Jason Treat, NG Staff, and Mesa Schumacher, Art: Davide Bonadonna, Source: Dr. Nizar Ibrahim, University of Detroit Mercy)

The Portsmouth spokeswoman said: “The team found that in place of a stiff tapering tail, typical of other theropod dinosaurs such as the Tyrannosaurus Rex, the tail vertebrae of Spinosaurus had extraordinarily long spines that supported a large, highly flexible, fin-like tail comparable in shape to that of a crested newt.

“After preparing all the fossils, the team used photogrammetry to digitally capture the anatomy of the tail.

Read more about dinosaurs:

“To quantitatively assess the performance of the tail, a team of Harvard researchers made a flexible model of the tail and attached it to a robotic system that mimics swimming movements.

“They then compared the swimming performance of the Spinosaurus tail to model tails from other animals, including dinosaurs, crocodiles and newts.

“The results are fully consistent with the idea of a truly water-dwelling, tail-propelled, ‘river monster’.”

Reconstruction of Spinosaurus (University of Portsmouth/PA)
Reconstruction of Spinosaurus © University of Portsmouth/PA

Professor David Martill, professor of palaeobiology at Portsmouth, said: “One thing that still puzzles me though, is why only Spinosaurus became aquatic among the dinosaurs. Why are there no aquatic iguanodons, or stegosaurs?”

Paleontologist Dr Nizar Ibrahim, of the University of Detroit Mercy and a National Geographic Explorer, said: “This discovery is the nail in the coffin for the idea that non-avian dinosaurs never invaded the aquatic realm.”

The research was published in the journal Nature.

Reader Q&A: What was the first dinosaur?

Asked by: Adam King, Huddersfield

As palaeontologists uncover more fossils around the world, we keep finding new dinosaurs from the Triassic Period: the first interval of dinosaur history.

Currently, the oldest known dinosaurs come from Argentina, and they’re about 231 million years old. There are several dinosaurs of this age found together, including the horse-sized meat-eater Herrerasaurus, the dog-sized meat-eater Eodromaeus (a distant relative of T. rex), and several dog-to-bear-sized cousins of the giant long-necked sauropods, including Panphagia and Eoraptor.

The fact that so many dinosaurs, with different diets and sizes, lived at this time tells us that dinosaurs were already diversifying soon after they evolved from other reptiles. But none of these dinosaurs were giants, and none were at the top of the food chain. Those species would come later, during the Jurassic Period.

Read more:

Authors


Alexander McNamara

Alexander is the Online Editor at BBC Science Focus and is the one that keeps sciencefocus.com looking shipshape and Bristol fashion. He has been toying around with news, technology and science on internet for well over a decade, and sports a very fetching beard.

Read More