Dinosaur age crocodilians, new research


This video says about itself:

4 May 2018

Evolution of crocodiles: Of all the reptiles alive today, crocodiles and alligators may be the least changed from their prehistoric forebears of the late Cretaceous period, over 65 million years ago—although the even earlier crocodiles of the Triassic and Jurassic periods sported some distinctly un-crocodile-like features, such as bipedal postures and vegetarian diets.

Along with pterosaurs and dinosaurs, crocodiles were an offshoot of the archosaurs, the “ruling lizards” of the early to middle Triassic period; needless to say, the earliest dinosaurs and the earliest crocodiles resembled one another a lot more than either resembled the first pterosaurs, which also evolved from archosaurs.

1. Xilousuchus
250,000,000 bc – 200,000,000 bc
2. Phytosaur
228,000,000 bc – 199,000,000 bc
3. Erpetosuchus
200,000,000 bc
4. Sarcosuchus
110,000,000 bc
5. Stomatosuchus
100,000,000 bc – 95,000,000 bc
6. Deinosuchus
80,000,000 bc
7. Champsosaurus [not a crocodile, though looking like one]
70,000,000 bc – 50,000,000 bc
8. Cretaceous-Paleogene Extinction Event
65,000,000 bc
9. Crocodylidae (Modern day crocodile)
55,000,000 bc – Present
10. Quinkana
23,000,000 bc – 40,000 bc
11. Crocodylus thorbjarnarsoni
4,200,000 bc

From the University of the Witwatersrand in South Africa:

In the gaping mouth of ancient crocodiles

As an apex predator, the crocodile’s mode of attack — its mouth — had humble beginnings

June 18, 2018

Summary: A new study has endeavoured to further explore the mouth of one of the earliest occurring and least understood groups of crocodilians, the shartegosuchids.

The mouth of today’s crocodilians inspires fear and awe, with their wide gape and the greatest known bite force in the vertebrate animal kingdom. However, this apex predator of today and its modus of attack (its mouth) had humble beginnings.

The very earliest crocodilians were very different to the beasts we know well today, they were much smaller bodied, slender and had longer legs. It is speculated that they led a much different lifestyle to the crocodiles we all know and fear today.

A new study by a team of international experts, led by University of Witwatersrand PhD candidate Kathleen Dollman and Professor Jonah Choiniere published today in the American Museum Novitates, endeavoured to further explore the mouth of one of the earliest occurring and least understand groups of crocodilians, the shartegosuchids.

In 2010, Choiniere was a part of a field team working in the Late Jurassic (±160 mya) exposures in the western Gobi in Mongolia, when he found the fossil of a small snout of a shartegosuchid. This work was co-authored by researchers based at the American Museum of Natural History, the George Washington University and the Institute for Vertebrate Palaeontology and Palaeoanthropology.

The snout was later CT scanned at the American Museum of Natural History, exposing an unusual, closed secondary palate. Crocodilians are one of only a few groups of animals that evolve a completely closed, bony secondary palate (along with turtles and mammals). A closed secondary palate has many biological implications for crocodilians, including breathing whilst under water and reinforcing the skull to allow for their incredible bite force.

This study showed that these early crocodilians, the shartegosuchids, are important because they evolved a completely closed secondary palate much earlier than previously thought. This is an interesting example of convergent evolution, whereby a similar feature evolves independently in two completely unrelated groups. The advent of a convergent evolutionary event allows scientists to test questions about why that feature evolved and even the function of that feature which in this case is the first step in understanding the purpose of a closed secondary palate in crocodilians.

“I was surprised to find that there were many features in the palate and snout that were completely different between shartegosuchids and extant crocodilians,” says Dollman. Shartegosuchids have a thickened and sculptured palate together with a tall and short rostrum, whereas extant crocodilians have a smooth palate with a long and broad rostrum.

“We would expect to see the same palatal structures and snout shapes in both shartegosuchids and extant crocodiles if they were using it for similar functions and had evolved a closed palate for similar reasons”, says Dollman. “The observed differences tell us that shartegosuchids likely had predation practices to which there is no modern analogue in crocodilians.”

“It’s been nearly 10 years since we collected this fossil after driving 5 days across the Gobi Desert,” said Choiniere, “and I am delighted that it’s formed a part of Kathleen’s PhD.”

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Jurassic World new film, comments


This video from the USA says about itself:

Thoughts on Jurassic World: Fallen Kingdom (NO SPOILERS)

10 June 2018

Here’s how we felt about Jurassic World: Fallen Kingdom, the newest continuation of my favourite film of all time! This is a very subjective review as we’re talking about our opinions of the film, and you probably won’t agree with everything we say. We also don’t talk about any major plot points that haven’t been shown in trailers here, so don’t worry about spoilers!

BBC: The plot might be ludicrous and the CGI below par, but the latest dinosaur blockbuster is ‘good old-fashioned summer entertainment’, according to Nicholas Barber.

Permian mammal-like reptile discoveries in Russia


This 8 June 2018 video is called Two new species of fearsome saber-toothed prehistoric predators have been found in Russia.

From the North Carolina Museum of Natural Sciences in the USA:

‘Monstrous’ new Russian saber-tooth fossils clarify early evolution of mammal lineage

June 8, 2018

Fossils representing two new species of saber-toothed prehistoric predators have been described by researchers from the North Carolina Museum of Natural Sciences (Raleigh, USA) and the Vyatka Paleontological Museum (Kirov, Russia). These new species improve the scientists’ understanding of an important interval in the early evolution of mammals — a time, between mass extinctions, when the roles of certain carnivores changed drastically.

Living mammals are descended from a group of animals called therapsids, a diverse assemblage of “protomammals” that dominated terrestrial ecosystems in the Permian Period (~299-252 million years ago), millions of years before the earliest dinosaurs. These protomammals included tusked herbivores, burrowing insectivores, and saber-toothed predators. The vast majority of Permian therapsids have been found in the Karoo Basin of South Africa, and as a result, the South African record has played an outsized role influencing scientists’ understanding of protomammal evolution. Because of this, therapsid fossils from outside of South Africa are extremely important, allowing scientists to discern whether observed events in the protomammal fossil record represent global or merely regional patterns.

Recent expeditions by the Vyatka Paleontological Museum have collected a wealth of spectacularly-preserved Permian fossils near the town of Kotelnich along the Vyatka River in European Russia. These fossil discoveries include the remains of two previously unknown species of predatory protomammals, newly described in the journal PeerJ by Christian Kammerer of the North Carolina Museum of Natural Sciences and Vladimir Masyutin of the Vyatka Paleontological Museum. The first of the two new species, Gorynychus masyutinae, was a wolf-sized carnivore representing the largest predator in the Kotelnich fauna. The second new species, Nochnitsa geminidens, was a smaller, long-snouted carnivore with needle-like teeth. Gorynychus belongs to a subgroup of protomammals called therocephalians (“beast heads”), whereas Nochnitsa belongs to a different subgroup called gorgonopsians (“gorgon faces”).

Both new species are named after legendary monsters from Russian folklore, befitting their menacing appearances. Gorynychus is named after Zmey Gorynych, a three-headed dragon, and Nochnitsa is named after a malevolent nocturnal spirit. (Based on their relatively large eye sockets, it is likely that Nochnitsa and its relatives were nocturnal.)

Gorynychus and Nochnitsa improve scientists’ understanding of ecosystem reorganization after the mid-Permian extinction (260 mya). Although not as well-known as the more devastating end-Permian mass extinction (252 mya, which nearly wiped out protomammals), the mid-Permian mass extinction also played a major role in shaping the course of protomammal evolution. In typical late Permian ecosystems, the top predators were giant (tiger-sized), saber-toothed gorgonopsians and therocephalians were generally small insectivores. In mid-Permian ecosystems, by contrast, these roles are reversed. At Kotelnich, the saber-toothed top predator Gorynychus is a therocephalian and the only gorgonopsians are much smaller animals.

“In between these extinctions, there was a complete flip-flop in what roles these carnivores were playing in their ecosystems — as if bears suddenly became weasel-sized and weasels became bear-sized in their place”, says Kammerer. The new species from Russia provide the first evidence that there was a worldwide turnover in predators after the mid-Permian extinction, and not just a localized turnover in South Africa.

Kammerer adds, “Kotelnich is one of the most important localities worldwide for finding therapsid fossils — not only because they are amazingly complete and well-preserved there, but also because they provide an all-too-rare window into mammal ancestry in the Northern Hemisphere during the Permian.”

What pterosaurs ate, new research


This video says about itself:

Reptiles of the Skies | Walking with Dinosaurs in HQ | BBC

The Cretaceous period saw the breaking up of the northern and southern landmasses. Flying dinosaurs like Tapejara would master the air and the new coast lines of prehistoric Earth. The largest flying dinosaur Ornithocheirus prepares for a long flight to breeding grounds.

Broadcast in 1999, Walking with Dinosaurs set out to create the most accurate portrayal of prehistoric animals ever seen on the screen. Combining fact and informed speculation with cutting-edge computer graphics and animatronics effects, the series took two years to make.

Pterosaurs are not ‘flying dinosaurs’, though they lived at the same time as dinosaurs.

From the University of Leicester in England:

Jurassic diet: Why our knowledge of what ancient pterosaurs ate might be wrong

Research reveals knowledge of prehistoric diets is often based on outdated ideas and could be inaccurate

June 7, 2018

Whenever we think about extinct animals we often imagine them eating their favourite meals, whether it be plants, other animals or a combination of both.

But are our ideas about extinct diets grounded within scientific reasoning, or are they actually little more than conjecture and speculation?

New research, published in Biological Reviews and led by a team of palaeobiologists from the University of Leicester, has revealed that the diets of pterosaurs are largely based on ideas that have been uncritically accepted for decades, or even centuries — and may often be wrong.

The study shows that one group of extinct animals where our dietary knowledge is lacking are the pterosaurs; extinct flying reptiles who lived in the Mesozoic Period 215-66 million years ago.

The research involved a comprehensive analysis of the scientific literature, summarising over 300 statements from 126 studies about the diets of pterosaurs, and the types of evidence used to support ideas of what they ate.

The research shows the vast majority of ideas about pterosaur diet are based on inferences drawn from modern organisms and/or the environments in which pterosaur fossils are preserved. These are not always reliable.

Jordan Bestwick, a PhD student from the School of Geography, Geology and the Environment, and lead author of the study, said: “Working out the diets of extinct animals is vitally important for understanding how they fitted within their respective ecosystems, which can tell us about how present ecosystems function and may change in the future.

“Being able to robustly test ideas is a key attribute of the scientific process, and helps us fully understand what we can know about the lifestyles of extinct animals, and what we can never know.”

Analysis reveals that over sixty percent of all hypotheses of pterosaur diet are based on simplistic anatomical comparisons between pterosaurs and modern organisms, particularly of the skulls and teeth. A key problem with this is that many of these interpretations are difficult, if not impossible, to test.

Jordan explained: “The potential range of pterosaur diets has been reviewed in the past but little attention has been paid to the evidence, if any, that support dietary interpretations. We realised that not only was it important to discover what we know about pterosaur diets, but to also find out how we know what we know about pterosaur diets.

“We find for some pterosaurs there is strong agreement among researchers as to their likely diet. Pteranodontids for example, which include one of the best known pterosaurs, Pteranodon, are almost unanimously agreed to have been fish feeders, an idea that is independently supported by multiple lines of evidence.

“In contrast, there is far less agreement as to what the giant azhdarchid pterosaurs ate. Azhdarchids can reach sizes of up to 10 metres or more in wingspan, like Hatzegopteryx, and there have been at least six different diets argued for these pterosaurs.”

This is not to say there are no methods or techniques that yield reliable evidence for understanding diets in these extinct animals. Biomechanical analysis of how hard pterosaurs could bite, and flight modelling that predicts how pterosaurs may have foraged for food have proven useful for understanding what some pterosaurs may or may not have eaten.

However techniques like these are employed in a small minority of studies and as such, it is currently not possible to identify the biological reasons that might explain the range and diversity of pterosaurs diets.

Dr David Hone from the Queen Mary University of London, who was not involved in the study, commented: “This is an important summary of what we know (and what we don’t) about what these animals fed on. This gives pterosaur researchers an excellent and critical starting point and a roadmap for future research on the diets of pterosaurs, and more broadly for all extinct animals.”

Australian lizards scare predators with ultra-violet light


This February 2018 video from Australia says about itself:

On this episode of Breaking Trail, Coyote catches a Blue Tongue Skink! While exploring the Australian outback just outside the town of Meandarra the team stumbles upon this large snake-like lizard!

Infamous for their large blue tongue defensive display, this species is well known in pet trades around the world. Get ready to meet Australia’s favorite skink!

From ScienceDaily:

Australian lizard scares away predators with ultra-violet tongue

Researchers investigate how the blue-tongued skink uses a full-tongue display to deter attacking predators

June 7, 2018

When attacked, bluetongue skinks open their mouth suddenly and as wide as possible to reveal their conspicuously coloured tongues. This surprise action serves as their last line of defence to save themselves from becoming prey says Martin Whiting, of Macquarie University in Australia, who conceived the study just published in Springer’s journal Behavioral Ecology and Sociobiology. The research revealed that the back of the northern bluetongue skink‘s tongue is much more UV-intense and luminous than the front, and that this section is only revealed in the final stages of an imminent attack.

Bluetongued skinks of the genus Tiliqua are medium-large sized lizards widely found throughout Australia, eastern Indonesia and Papua New Guinea. They are well camouflaged but their strikingly blue tongues are distinct and are UV-reflective in species in which this has been measured. When attacked, they open their mouths wide to reveal their tongues.

The research team set out to investigate the tactics that bluetongue skinks use to ward off attackers, and focused on the largest of the bluetongue skinks, the northern bluetongue skink (Tiliqua scincoides intermedia). This omnivorous, ground-dwelling lizard of northern Australia is well camouflaged thanks to the broad brown bands across its back. However, birds, snakes, monitor lizards — all animals thought to have UV vision — are among its main predators.

First the researchers gathered information about the colour and intensity of different parts of the lizard’s tongue using a portable spectrophotometer to measure the tongues of thirteen skinks. The first exciting finding was that the blue tongue is actually a UV-blue tongue. The researchers then established that the rear of the skinks’ tongues was almost twice as bright as the tips. When a predator approached, the skinks would remain camouflaged until the very last moment, before opening their mouths widely and revealing their highly conspicuous UV-blue tongues.

The next part of the study involved simulating ‘attacks’ on these lizards using model (fake) predators. The team used a snake, a bird, a goanna (monitor lizard), a fox and a piece of wood as a control. The model predator attacks were simulated within a controlled environment.

“The lizards restrict the use of full-tongue displays to the final stages of a predation sequence when they are most at risk, and do so in concert with aggressive defensive behaviours that amplify the display, such as hissing or inflating their bodies,” explains lead author Arnaud Badiane. “This type of display might be particularly effective against aerial predators, for which an interrupted attack would not be easily resumed due to loss of inertia.”

The more intense the attack and the risk they were experiencing, the more full-tongue displays the animals were seen to use, and the greater section of their tongues they would reveal. Such displays were also most often triggered by attacking birds and foxes, rather than by snakes or monitor lizards.

“The timing of their tongue display is crucial,” adds Badiane. “If performed too early, a display may break the lizard’s camouflage and attract unwanted attention by predators and increase predation risk. If performed too late, it may not deter predators.”

Triassic reptiles, unrelated to, but looking like, modern animals


This video from the USA says about itself:

Why Triassic Animals Were Just the Weirdest

5 June 2018

The Triassic was full of creatures that look a lot like other, more modern species, even though they’re not closely related at all.

The reason for this has to do with how evolution works and with the timing of the Triassic itself: when life was trapped between two mass extinctions.

Thanks to Ceri Thomas for the Drepanosaurus reconstruction. Check out more of Ceri’s paleoart at http://alphynix.tumblr.com and http://nixillustration.com.

And thanks as always to Nobumichi Tamura for allowing us to use his wonderful paleoart: http://spinops.blogspot.com/.

Finally, thanks to Emilio Rolandia, Matt Celeskey, and Studio 252mya for their excellent images as well.