Tag: palaeontology

Dinosaurs were animal world’s top bone heads

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Scientists have compared a dinosaur with several modern-day animals to settle who wins the heavy-weight head-butting title.

The new findings confirm that the ancient bipedal dinosaur Stegoceras could knock out any of today’s top head-butters.

Stegoceras probably used their domed skulls to ram each other over access to fertile females.

The hard-hitting research was published in the journal PLoS ONE.

Stegoceras was a member of the leaf-eating genus Pachycephalosauria that roamed the Earth around 70 million years ago.

The goat-sized dinosaur supported a 7.5cm (~3 inches) thick bony skull, which some palaeontologists believe acted as a shock-absorber when these animals ran at each other.

Big hitters

However, images of the insides of Stegoceras‘ fossilised skull, which reveal two layers of dense bone that encase a spongy sinus held apart by tiny struts, has led some scientists to doubt this interpretation.

Hoping to clear up the controversy, biomedical engineer Dr Eric Snively wandered down the corridor at the University of Calgary in Alberta, Canada to enlist the help of colleague Dr Jessica Theodor, a vertebrate palaeontologist.

The duo performed computer tomographic (CT) scans on the skulls of Stegoceras, along with a variety of modern animals, and used these bone density measurements to create 3D models of the animals’ heads.

The team was then able to exert virtual stresses to test how the different skulls held up.

Compared to some of today’s big hitters, such as the Northern American bighorn sheep, the Arctic musk ox and African duiker, Stegoceras ‘ head was able to withstand the most stress.

“The argument that they couldn’t withstand the forces of head-butting seems to have been refuted by this evidence,” said Dr Theodor.

Crushing collisions

Dr Snively explained that if two animals ran at each other with a combined speed of 6.7 metres (22 feet) per second, which he estimates to be a realistic speed, Stegoceras‘ dome-head would have had to withstand an impact of over 13,000 Newtons (2,918 pounds-force).

“In human terms, that’s like balancing a Ford Focus on your head,” Dr Snively told BBC News.

“Even at these forces, only a few struts of bone might break; these would heal easily,” he said.

Offering further protection from these crushing collisions, Stegoceras‘ head was covered by a layer of keratin, the material nails are made from, and articulations between the vertebrae would have let the “backbone scrunch up like an accordion”, explained Dr Snively.

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The Earliest Touchdown

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Three hundred million years ago, a flying insect skidded to a landing on a muddy patch of earth and preserved a 3.5-centimeter-long imprint for eternity. From the position of the legs, the curve of the abdomen, and the lack of wing marks, the researchers suspect that the imprint was made by an ancient mayfly that held its wings upright when at rest. Collected in southeastern Massachusetts, the fossil is the oldest known full-body impression of a flying insect, the team reports online today in the Proceedings of National Academy of Sciences. The ability of today’s insects to skim the surface of water is thought to be a modern invention. But the discovery of tiny drag marks (see inset) that suggest that mayflies likely slide before stopping is at least enough to prompt some paleontologists to keep an open mind on the matter.

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The Oldest Buttercup Yet

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Darwin called the origin of flowering plants an “abominable mystery.” They appear in the fossil record and immediately grow abundant and varied, creating a problem for his theory of slow but continuous change. The unearthing of a new fossil in northeast China, described online today in Nature, could explain the apparent contradiction. The ancient flowering plant, Archaefructus liaoningensis, resembles a modern-day buttercup, with slender stems and three-lobed leaves. Its discovery pushes back the date of when flowering plants diversified to around 127 million years ago, during the early Cretaceous period. That’s a couple of million years earlier than Darwin had previously thought, suggesting that these ancient blooms had longer to evolve than he suspected.

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Ancient ‘Seaweed’ Rewrites History

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The discovery of leaf-thin, seaweed-like fossils in China nudges back the moment when ancient life went from microscopic to merely tiny. At 600 million years old, the new fossils—called the Lantian Formation—are 27 million years older than the so-called Avalon fossils found in Canada and England, which, until now, were the earliest known fossil assemblage of multicellular life. The new specimens, some resembling modern day seaweeds, represent 15 or so photosynthetic algae researchers report online today in Nature. Unlike the Avalon fossil organisms, which thrived in deep-water environments, these ancient “seaweeds” lived in shallow marine seas. That means paleontologists need to rethink their theory that oxygenation of the deep oceans triggered the rise of more complex organisms.

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Dinosaur Munchies May Have Bulked Up Pinecones

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The next time you step on a big, spiky pinecone, blame a dinosaur. A new study suggests that these seed carriers used to be soft and thin but that they had to toughen up when dinos with long necks started nibbling on them.

Conifers, such as today’s cypresses, Douglas firs, and giant redwoods, produce two types of cones: slender male cones that release pollen and bulky female cones that house the seeds. Ancient conifers also produced two cones, but palaeobotanist Andrew Leslie of Yale University noticed that they were both slim and unassuming, like today’s male cones.

Eager to find out what made the female cones bulk up, Leslie scoured the world’s herbariums—calipers in hand—in search of well-preserved fossil conifers. He compared the 70 or so specimens he found with more than 200 living species. Leslie’s early observation stood up: Female cones have gotten fatter. This widening was not a result of larger seeds but instead a broadening of the scales with which the cone arms itself against grazers, he reports online today in the Proceedings of the Royal Society B.

Leslie found the first cases of wider seed cones in the Jurassic period, a time when very large vertebrate herbivores, such as the long-necked sauropods Diplodocus and Barapasaurus, roamed Earth. These dinosaurs would have been able to graze much higher than earlier species, putting female cones at risk.

Scientists are still debating whether sauropods lifted their necks to feed from the tops of trees, as giraffes do. But even without reaching up, they could graze up to a height of 5 meters. “This still represents a notable increase in browsing height compared to previous vertebrate herbivores, which were mostly browsing around 1 meter or less,” Leslie says.

“It is quite a striking pattern now that someone has pointed it out,” says plant evolutionary biologist Peter Crane of Yale, who was not involved in the study. Still, one shouldn’t rush to blame sauropods, he says. “I don’t think we should forget early birds and mammals.”

Leslie agrees: “The fossil record is pretty useless for showing what was living up in the trees.” This makes it difficult to establish whether conifers were arming themselves against taller dinosaurs or against early mammals and birds that were also beginning to appear in the late Jurassic and early Cretaceous periods. Even insects could have played a role. “We also see an increase in the types of insect mouth parts,” Leslie says, so insects could have broadened their diets to include conifer cones.

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Open Science

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What is open science? I talk to Michael Nielsen about Open Notebook Science, the Galaxy Zoo Project and the Open Dinosaur Project for CBC’s Spark to get at what happens when science opens up to everyone by moving online.

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Canadian dig yields tiny dinosaur

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The smallest meat-eating dinosaur yet to be found in North America has been identified from six tiny pelvic bones.

Hesperonychus was the size of a small chicken, and used its rows of serrated teeth to feed on insects, experts say.

The bird-like creature is closely related to Microraptor – a tiny feathered dinosaur discovered in China.

The specimen helps to confirm that reptiles, and not mammals, filled the role of small predators during the age of the dinosaurs.

The fossil skeleton, which lay misidentified for 25 years as a lizard, belongs to a group of dinosaurs called the theropods – bipedal reptiles that eventually gave rise to birds.

“Despite the discovery of exquisitely preserved skeletons of small bird-like dinosaurs in Asia, they are exceedingly rare in North America,” explained Dr Philip Currie, a palaeontologist from the University of Alberta and co-author on the paper.

Dr Currie had been pondering why so few small fossils have been unearthed in Alberta, Canada – one of the world’s richest sites for large-dinosaur bones.

Infographic (BBC)

 

He suspected that small dinosaurs did not preserve well in the region of the prevalence of larger predators in the area.

“There were many large dinosaurs running around eating them, and small bones are easily washed away by rivers [common in this region during the Cretaceous period]”, Dr Currie said.

The new find casts more doubt on whether mammals would have acted as small predators in Cretaceous-era North America. The fossilised pelvis came from an animal that weighed no more than 1.9kg (4.2lb) and appears distinctively reptilian.

“This tells us that [as in Asia], North American dinosaurs likely out-competed mammals for both large and small predator niches,” Dr Currie told BBC News.

‘Tree-hugging raptor’

The authors also suggest this discovery helps to resolve debate over whether flight originated from animals that ran on the ground, flapping their arms, or whether it started with tree-climbing animals gliding downwards.

Based on the size of the hips, and because one of the hip bones was bent – the pubis, a small bone that sits between the legs – “we know this dinosaur was a tree-climber”, Dr Currie explained.

“It likely used the long feathers on its limbs to glide or parachute from tree to tree.”

The specimen, Hesperonychus elizabethae – named after its collector Dr Elizabeth Nicholls – was reclassified by palaeontolgist Dr Nicholas Longrich, a co-author of the paper, from the University of Calgary.

The findings were reported in a recent article in the journal Proceedings of National Academy of Sciences.

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Ancient shark had colossal bite

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Shark

The great white shark may have awesome jaws but they are nothing compared with those of megalodon, its gigantic, whale-eating ancestor.

A new study of the extinct creature’s skull shows it had an almighty bite, making the prehistoric fish one of the most fearsome predators of all time.

All the more remarkable, scientists say, because the crushing force came from jaws made of cartilage, not bone.

The researchers report their skull work in the Journal of Zoology.

The Carcharodon megalodon super-shark swam in the oceans more than a million-and-a-half years ago.

It grew up to 16m (52ft) in length and weighed in at 100 tonnes – 30 times heavier than the largest great white – and must have been one of the most formidable carnivores to have existed.

“Pound for pound, your common house cat can bite down harder, ” explained Dr Stephen Wroe of the University of New South Wales, Australia. “But the sheer size of the animal means that in absolute terms, it tops the scales.”

Measuring up

Dr Wroe’s team used a technique known as finite element analysis to compare the skulls of the great white with that of the prehistoric megalodon.

The approach is a common one in advanced design and manufacturing, and allows engineers to test the performance of load-bearing materials, such as the metal in the body and wings of an aeroplane.

CT (X-ray) scans were taken of megalodon remains to construct a high-resolution digital model.

A model of a modern 2.4m-long male great white shark (Carcharodon carcharias) was developed for comparison.

Artist's impression: Megalodon (BBC)

A recent BBC series imagined a face-to-face encounter

The model of Megalodon’s muscles was based on those of the great white, and the simulations were then loaded with forces to see how the two skulls, jaws, teeth and muscles would have coped with the mechanical stresses and strains experienced during feeding.

By looking at the distribution of stress and strain on the sharks’ jaws, researchers found that the largest great whites have a bite force of up to 1.8 tonnes, three times the biting force of an African lion and 20 times harder than a human bites.

Megalodon, though, is more impressive. It is estimated to bite down with a force of between 10.8 to 18.2 tonnes.

The team said biting with such force was quite a feat given that the jaws of these ancient creatures were made of flexible cartilage.

In contrast to most other fish, sharks’ skeletons are made up entirely of cartilage. Scientists think that cartilage, being a much lighter material than bone, is one adaptation that allows sharks to swim without the aid of a swim bladder.

With finesse

The Australian research team was interested in how a cartilaginous jaw performs compared with a bone jaw.

The scientists’ study shows that the cartilaginous jaw is almost as strong as a bony jaw of the same size – losing only a few percent – in measures of bite force. What is more, the elasticity of the cartilage jaw increases the gape of the sharks to devastating ends.

“The shark’s upper jaws can be dislocated: the whole upper and lower jaw pull out and forward as the shark twists and shakes its head from side to side to bite a chunk out of its prey,” explains Dr Wroe.

These sharks feed on very large prey: the great white shark eats sea lions and the megalodon is thought to have eaten whales.

“These sharks ambush their prey and immobilise them with a bite, then wait for them to die,” Dr Wroe told BBC News. “They are actually delicate feeders and take care not to damage their teeth by biting down too hard on the large bones of their prey.”

To keep their teeth sharp, sharks have a battery of them that is continually replaced.

It is the combination of their size, their razor-sharp teeth and the element of surprise that makes these sharks such deadly predators.

MEGALODON COMPARED WITH THE GREAT WHITE SHARK

Shark graphic
Megalodon Great white shark
Type Cartilaginous fish Cartilaginous fish
Size 16m (52ft) 6m (20ft)
Diet Whales, including the now extinct Odobenocetops, seals Fish, turtles, seals, sea lions, squid and crustaceans
Predators None known Occasionally caught by fishing industry as bycatch

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