Ornithopod dinosaur teeth, new study


The skull of the holotype specimen of Changchunsaurus parvus (JLUM L0304-j-Zn2). Credit: Chen et al., 2018 CC-BY

From PLOS:

The teeth of Changchunsaurus: Rare insight into ornithopod dinosaur tooth evolution

Unexpected features in this dinosaur‘s teeth appear to represent early adaptations for herbivory

November 7, 2018

The teeth of Changchunsaurus parvus, a small herbivorous dinosaur from the Cretaceous of China, represent an important and poorly-known stage in the evolution of ornithopod dentition, according to a study released November 7, 2018 in the open-access journal PLOS ONE by Jun Chen of Jilin University in China and colleagues.

Ornithischian (“bird-hipped”) dinosaurs developed an incredible diversity of teeth, including the famously complex dental batteries of derived ornithopods, but little is known about how these intricate arrangements arose from the simple tooth arrangements of early dinosaurs. Changchunsaurus parvus belongs to an early branch at or near the origins of the ornithopods, and thus may provide insight into the ancestral state of ornithopod tooth development. In this study, Chen and colleagues took thin sections from five jaw bones of Changchunsaurus to investigate tooth composition as well as how the teeth are maintained throughout the life of the animal using histological techniques.

Among the notable features of Changchunsaurus dentition is a unique method of tooth replacement that allowed it to recycle teeth without disrupting the continuous shearing surface formed by its tooth rows. The authors also found that the teeth feature wavy enamel, a tissue type formerly thought to have evolved only in more derived ornithopods. The authors suspect these features may have arisen early on as this group of dinosaurs became specialized for herbivory.

Features of the jaws and teeth are often used to assess dinosaur phylogeny. In addition to investigating the evolution of ornithopod dentition, this study also identifies new dental traits that might help sort out ornithischian relationships in future analyses. But the authors note that this is only the first in-depth study at a dinosaur near the base of the ornithopod family tree, and that more studies on more dinosaurs will be needed to fill in the full picture of this group’s evolution.

Professor Chen Jun summarizes: “These tissue-level details of the teeth of Changchunsaurus tell us that their teeth were well-adapted to their abrasive, plant-based diets. Most surprisingly, the wavy enamel described here, presumably to make it more resistant to wear, was previously thought to be exclusive to their giant descendants, the duckbilled dinosaurs.”

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New dinosaur species discovery in Argentina


Lavocatisaurus agrioensis, picture: Acta Palaeontologica Polonica

From AFP news agency today:

Paleontologists discover new sauropod species in Argentina

Buenos Aires: Buenos Aires (AFP) – A team of Spanish and Argentine paleontologists have discovered the remains of a dinosaur that lived 110 million years ago in the center of the country, the National University of La Matanza revealed Friday.

The remains came from three separate dinosaurs from the herbivorous group of sauropods, the best known of which are the Diplodocus and Brontosaurus. This new species has been named Lavocatisaurus agrioensis.

“We found most of the cranial bones: the snout, the jaws, a lot of teeth, also the bones that define the eye sockets for example and, in that way, we were able to create an almost complete reconstruction,” said Jose Luis Carballido, a researcher at the Egidio Feruglio museum and the national council of scientific investigations.

Parts of the neck, tail and back were also found.

“Not only is this the discovery of a new species in an area where you wouldn’t expect to find fossils, but the skull is almost complete”, added Carballido.

The remains belonged to an adult of around 12 meters (39 feet) in length, and two minors of around six to seven meters.

The paleontologists say the dinosaurs moved around in a group and died together.

“This discovery of an adult and two juveniles also signifies the first record of a group displacement among the rebbachisaurus dinosaurs”, said study lead author Jose Ignacio Canudo of Zaragoza University.

The area in which the fossils were found is unusual for dinosaurs as it would have been a desert with sporadic lakes in that era.

Sauropods were the biggest creatures ever to walk the planet. It is believed that Supersaurus could reach up 33-34 meters in length and Argentinosaurus might have weighed up to 120 tons.

They were herbivorous quadrupeds with long necks and tails, massive bodies and small heads.

But the discovery in Neuquen, published in the scientific journal Acta Palaeontologica Polonica, remains a huge surprise.

“While one can imagine that this group of sauropods could have adapted to move in more arid environments, with little vegetation, little humidity and little water, it’s an area in which you wouldn’t be looking for fossils”, said Carballido.

Colourful dinosaur and bird eggs, new study


Reptile and bird eggs. Wiemann, T.-R. Yang and M.A. Norell/Nature 2018

By Carolyn Gramling, 4:05pm, October 31, 2018:

Eggs evolved color and speckles only once — during the age of dinosaurs

Analysis of pigmentation in the eggs of modern birds and nonavian dinosaurs suggests similarities

The colorful, speckled eggs of modern birds are an innovation inherited from their nonavian dinosaur ancestors.

A new analysis of the pigmentation in modern and fossilized eggshells suggests that eggs evolved to be colorful only once — in modern birds’ dinosaur ancestors, a team of vertebrate paleontologists report online October 31 in Nature. Color patterns found in the eggshells of theropod dinosaurs, a lineage that includes Tyrannosaurus rex and smaller winged dinosaurs such as Microraptor, were very similar to those of modern birds, says Jasmina Wiemann, of Yale University.

Scientists once thought only birds produced colorful eggshells, says coauthor Mark Norell of the American Museum of Natural History in New York City. But a growing body of literature suggests that many traits once thought to be unique to birds — feathers, flight, brain organization and adaptive metabolisms needed for flight — evolved long before modern birds did (SN: 4/14/18, p. 9; SN: 5/26/18, p. 8; SN Online: 10/19/18). “It’s kind of blurring the line between what’s a bird and what’s a [nonavian] dinosaur”, Norell says.

Bird eggs get their color from two pigments: a red-brown pigment called protoporphyrin, which creates speckles and is found only in an eggshell’s soft, outer cuticle layer; and a blue-green pigment called biliverdin, found in the deeper, crunchier part of the shell. In 2015, Wiemann and her colleagues reported that fossilized eggshells of Heyuannia huangi, a short-beaked, crested dinosaur that lived about 70 million years ago, contained traces of both pigments (SN: 6/27/15, p. 14).

Eggstravaganza

Researchers found no traces of pigment in eggshells belonging to a long-necked titanosaurid dinosaur, or in the eggs of a modern American alligator, both of which have buried nests. But traces of blue-green or red-brown pigments — or both — were found in the eggshells of theropod dinosaurs such as Deinonychus antirrhopus as well as such modern birds as the flightless greater rhea and the chicken, all of which have at least partially open nests.

In a pigment analysis, peaks correspond to the presence of particular molecules in the eggshell. The shell contains the pigment only if all the molecules in that pigment are present (pattern of dots), like a fingerprint.

That suggests a much older evolutionary origin of the pigments than thought. But Wiemann wanted to know how common eggshell coloration might have been among nonavian dinosaurs and their relatives. So her team, which included Tzu-Ruei Yang of the University of Bonn in Germany, used a technique called Raman spectroscopy to scan for traces of the two pigments in the eggshells of 19 species on the extended family tree. Those species ranged from the American alligator to modern birds such as the chicken and emu to nonavian dinosaurs.

The technique uses a laser beam to scatter light off molecules in the shells, with the pigments producing peaks at characteristic wavelengths — like a fingerprint match. The researchers also analyzed the eggshells of a variety of nonavian dinosaurs, including more than half a dozen different theropod species, the herbivorous crested ornithischian Maiasaura peeblesorum and a long-necked titanosaur.

Only the theropods had colored shells that contained one or both pigments, the team found. Pigment patterns, or where the color was distributed, were nearly identical between the eggs of modern birds and nonavian theropod dinosaurs. That suggests that coloration evolved only once, rather than multiple times among birds, the team reports.

“We can infer a lot of ecology and paleobiology based on color, such as nesting biology and behaviors”, Wiemann says. For example, the team found that the nonavian dinosaurs with colorful eggs also had open, or partially open, nests, where the dinosaurs sat directly on the eggs, as modern birds do (SN: 6/9/18, p. 32). The dinosaurs with colorless eggs, including the ornithischians and the sauropods, buried their eggs, like modern crocodiles and turtles do.

There are several possible reasons for an association between colorful eggs and open nests, including the need for camouflage. “In modern birds, the overall color tone of the eggs aims to mimic the color tone of the nesting environment”, Wiemann says. Colorful shells could have helped regulate incubating egg temperatures. And unique pigment patterns on the shells may have helped animals recognize their own eggs. “It suggests that the ecology is much more complex than we thought.”

The discovery that pigmented eggshells evolved in nonavian theropod dinosaurs “will change the way we think about dinosaur nesting and incubation behavior”, says Mary Caswell Stoddard, a vertebrate paleontologist at Princeton University who was not involved in the study. Stoddard notes that the find raises interesting questions about the diversity in ancient eggs that “behavioral ecologists and paleontologists will be asking in the years to come.”

A new study says the colors found in modern birds’ eggs did not evolve independently, as previously thought, but evolved instead from dinosaurs: here.

How Tyrannosaurus rex hunted armoured dinosaurs


This 30 October 2018 video says about itself:

How T-Rex Preyed on Armored Dinosaurs

The biting force of T-Rex was around 400,000 pounds per square inch – the strongest bite of any animal to walk the earth. This enabled it to prey on large, often well-armored giants like Triceratops.

Tyrannosaur Trix travels around the world


This 30 September 2018 video from the Netherlands says about itself:

Philips and Naturalis scan 66 million year old T. Rex, Trix

Working with Leiden’s Naturalis museum in the Netherlands, Philips offered to scan one of the world’s most complete and best preserved T. Rex skeletons. The aim of the scan was to evaluate how images of Trix’s tail vertebrae obtained using Philips’ IQon Spectral CT imaging differ from conventional CT images, and to provide a level of detail not visible to paleontologists until now.

“We make the invisible visible”, said Anne Schulp, paleontologist and dinosaur expert at Naturalis.

To find out more about the study, click here.

Dutch weekly Leids Nieuwsblad, 18 October 2018, reports about female Tyrannosaurus rex Trix, property of Naturalis museum in Leiden.

As Naturalis museum is now being reconstructed and closed to the public, Trix is on a world tour. Already over a million people came to see her. 293,000 in Leiden before the tour started; 85,000 in Salzburg in Austria; 380,000 in Barcelona. And 260,000 and still counting in Paris, where the dinosaur will be exhibited until 3 November. After that, Trix will go to Glasgow. In mid 1919, when the reconstruction will be finished, she will be in Naturalis again.

A new dinosaur museum will be built in Nagasaki, Japan. One of the exhibits will be a 3D replica of Trix.

New tyrannosaur dinosaur species discovered


This 22 October 2018 video says about itself:

Dynamoterror – A New Tyrannosaur

Recently a new species of Tyrannosaur was discovered, and it’s allowed palaeontologists to get a clearer view of how this iconic group first evolved.

About the discovery of this new species in New Mexico, USA: here.

Big dinosaur discovery in South Africa


This 27 September 2018 video says about itself:

Ledumahadi mafube – New Jurassic Giant of South Africa

A new species of a giant dinosaur has been found in South Africa’s Free State Province.

From the University of the Witwatersrand in South Africa:

Ledumahadi mafube: South Africa’s new Jurassic giant

September 27, 2018

A new species of a giant dinosaur has been found in South Africa’s Free State Province. The plant-eating dinosaur, named Ledumahadi mafube, weighed 12 tonnes and stood about four metres high at the hips. Ledumahadi mafube was the largest land animal alive on Earth when it lived, nearly 200 million years ago. It was roughly double the size of a large African elephant.

A team of international scientists, led by University of the Witwatersrand (Wits) palaeontologist Professor Jonah Choiniere, described the new species in the journal Current Biology today.

The dinosaur’s name is Sesotho for “a giant thunderclap at dawn” (Sesotho is one of South Africa’s 11 official languages and an indigenous language in the area where the dinosaur was found).

“The name reflects the great size of the animal as well as the fact that its lineage appeared at the origins of sauropod dinosaurs”, said Choiniere. “It honours both the recent and ancient heritage of southern Africa.”

Ledumahadi mafube is one of the closest relatives of sauropod dinosaurs. Sauropods, weighing up to 60 tonnes, include well-known species like Brontosaurus. All sauropods ate plants and stood on four legs, with a posture like modern elephants. Ledumahadi evolved its giant size independently from sauropods, and although it stood on four legs, its forelimbs would have been more crouched. This caused the scientific team to consider Ledumahadi an evolutionary “experiment” with giant body size.

Ledumahadi’s fossil tells a fascinating story not only of its individual life history, but also the geographic history of where it lived, and of the evolutionary history of sauropod dinosaurs.

“The first thing that struck me about this animal is the incredible robustness of the limb bones”, says lead author, Dr Blair McPhee. “It was of similar size to the gigantic sauropod dinosaurs, but whereas the arms and legs of those animals are typically quite slender, Ledumahadi’s are incredibly thick. To me this indicated that the path towards gigantism in sauropodomorphs was far from straightforward, and that the way that these animals solved the usual problems of life, such as eating and moving, was much more dynamic within the group than previously thought.”

The research team developed a new method, using measurements from the “arms” and “legs” to show that Ledumahadi walked on all fours, like the later sauropod dinosaurs, but unlike many other members of its own group alive at its time such as Massospondylus. The team also showed that many earlier relatives of sauropods stood on all fours, that this body posture evolved more than once, and that it appeared earlier than scientists previously thought.

Ledumahadi mafube is the first of the giant sauropodomorphs of the Jurassic. Credit: Wits University

“Many giant dinosaurs walked on four legs but had ancestors that walked on two legs. Scientists want to know about this evolutionary change, but amazingly, no-one came up with a simple method to tell how each dinosaur walked, until now”, says Dr Roger Benson.

By analysing the fossil’s bone tissue through osteohistological analysis, Dr Jennifer Botha-Brink from the South African National Museum in Bloemfontein established the animal’s age.

“We can tell by looking at the fossilised bone microstructure that the animal grew rapidly to adulthood. Closely-spaced, annually deposited growth rings at the periphery show that the growth rate had decreased substantially by the time it died”, says Botha-Brink. This indicates that the animal had reached adulthood.

“It was also interesting to see that the bone tissues display aspects of both basal sauropodomorphs and the more derived sauropods, showing that Ledumahadi represents a transitional stage between these two major groups of dinosaurs.”

Ledumahadi lived in the area around Clarens in South Africa’s Free State Province. This is currently a scenic mountainous area, but looked much different at that time, with a flat, semi-arid landscape and shallow, intermittently dry streambeds.

“We can tell from the properties of the sedimentary rock layers in which the bone fossils are preserved that 200 million years ago most of South Africa looked a lot more like the current region around Musina in the Limpopo Province of South Africa, or South Africa’s central Karoo”, says Dr Emese Bordy.

Ledumahadi is closely related to other gigantic dinosaurs from Argentina that lived at a similar time, which reinforces that the supercontinent of Pangaea was still assembled in the Early Jurassic. “It shows how easily dinosaurs could have walked from Johannesburg to Buenos Aires at that time”, says Choiniere.

South Africa’s Minister of Science and Technology Mmamoloko Kubayi-Ngubane says the discovery of this dinosaur underscores just how important South African palaeontology is to the world.

“Not only does our country hold the Cradle of Humankind, but we also have fossils that help us understand the rise of the gigantic dinosaurs. This is another example of South Africa taking the high road and making scientific breakthroughs of international significance on the basis of its geographic advantage, as it does in astronomy, marine and polar research, indigenous knowledge, and biodiversity”, says Kubayi-Ngubane.

The research team behind Ledumahadi includes South African-based palaeoscientists, Dr Emese Bordy and Dr Jennifer Botha-Brink, from the University of Cape Town and the South African National Museum in Bloemfontein, respectively.

The project also had a strong international component with the collaboration of Professor Roger BJ Benson of Oxford University and Dr Blair McPhee, currently residing in Brazil.

“South Africa employs some of the world’s top palaeontologists and it was a privilege to be able to build a working group with them and leading researchers in the UK”, says Choiniere, who recently emigrated from the USA to South Africa. “Dinosaurs didn’t observe international boundaries and it’s important that our research groups don’t either.”