Slow worm discovery on Ameland island


This video says about itself:

20 April 2014

A baby female Adder Vipera berus berus is shown curling up alongside an adult male Slow-worm Anguis fragilis. The tiny snake would have been born during the previous year and it is just as venomous as an adult.

Translated from the press agency of Ameland island in the Netherlands:

Slow worm seen on Ameland

July 25, 2015

HOLLUM – This Saturday, Annelies Lap from Hollum village saw on the horse trail near the Duck Pond a slow worm. She immediately photographed it.

It is a remarkable observation, because slow worms do not live on the Wadden Sea islands. In 2014 one was reported in a garden on Texel island. Ecomare museum on Texel suspects the animal lifted to the island, eg it made the sea crossing with compost or straw. Probably also the Ameland individual arrived like this as a stowaway on the island.

First four-legged snake fossil discovery


This video says about itself:

Tetrapodophis amplectus – A four-legged snake from the Early Cretaceous of Gondwana

24 July 2015

Tetrapodophis amplectus appears to be a four-legged snake from the Early Cretaceous of Gondwana. Dr. Dave Martill, from the University of Portsmouth, says that this discovery could help scientists to understand how snakes lost their legs.

From the BBC:

Four-legged snake ancestor ‘dug burrows’

By Jonathan Webb Science reporter, BBC News

24 July 2015

A 113-million-year-old fossil from Brazil is the first four-legged snake that scientists have ever seen.

Several other fossil snakes have been found with hind limbs, but the new find is estimated to be a direct ancestor of modern snakes.

Its delicate arms and legs were not used for walking, but probably helped the creature to grab its prey.

The fossil shows adaptations for burrowing, not swimming, strengthening the idea that snakes evolved on land.

That debate is a long-running one among palaeontologists, and researchers say wiggle room is running out for the idea that snakes developed from marine reptiles.

“This is the most primitive fossil snake known, and it’s pretty clearly not aquatic,” said Dr Nick Longrich from the University of Bath, one of the authors of the new study published in Science magazine.

Speaking to Science in Action on the BBC World Service, Dr Longrich explained that the creature’s tail wasn’t paddle-shaped for swimming and it had no sign of fins; meanwhile its long trunk and short snout were typical of a burrower.

“It’s pretty straight-up adapted for burrowing,” he said.

When Dr Longrich first saw photos of the 19.5cm fossil, now christened Tetrapodophis amplectus, he was “really blown away” because he was expecting an ambiguous, in-between species.

Instead, he saw “a lot of very advanced snake features” including its hooked teeth, flexible jaw and spine – and even snake-like scales.

“And there’s the gut contents – it’s swallowed another vertebrate. It was preying on other animals, which is a snake feature.

“It was pretty unambiguously a snake. It’s just got little arms and little legs.”

Deadly embrace?

At 4mm and 7mm long respectively, those arms and legs are little indeed. But Dr Longrich was surprised to discover that they were far from being “vestigial” evolutionary leftovers, dangling uselessly.

“They’re actually very highly specialised – they have very long, skinny fingers and toes, with little claws on the end. What we think [these animals] are doing is they’ve stopped using them for walking and they’re using them for grasping their prey.”

That comparatively feeble grasp, which may have also been applied during mating, is where the species gets its name. Tetrapodophis, the fossil’s new genus, means four-footed snake, but amplectus is Latin for “embrace”.

“It would sort of embrace or hug its prey with its forelimbs and hindlimbs. So it’s the huggy snake,” Dr Longrich said.

In order to try to pinpoint the huggy snake’s place in history, the team constructed a family tree using known information about the physical and genetic make-up of living and ancient snakes, plus some related reptiles.

That analysis positioned T. amplectus as a branch – the earliest branch – on the the very same tree that gave rise to modern snakes.

Neglected no more

Remarkably, this significant specimen languished in a private collection for decades, before a museum in Solnhofen, Germany, acquired and exhibited it under the label “unknown fossil”.

It was there that Dr Dave Martill, another of the paper’s authors, stumbled upon it while leading a student field trip. He told the Today programme on BBC Radio 4 they were principally visiting to see the museum’s famous Archaeopteryx fossil.

“All of a sudden my jaw absolutely dropped, when I saw this little fossil like a piece of string,” said Dr Martill, from the University of Portsmouth.

As he peered closer, he managed to spot the four tiny legs – and immediately asked the museum for permission to study the creature.

Dr Bruno Simoes, who studies the evolution of snake vision at the Natural History Museum in London, told the BBC he was impressed by the new find because the snake’s limbs are so well preserved, and appear so well developed.

“It’s quite a surprise, especially because it’s so close to the crown group – basically, the current snakes,” he said.

“It gives us a good idea of what the ancestral snake was like.”

Dr Simoes suggested that alongside several other recent findings, this new fossil evidence had clinched the argument for snakes evolving on land.

“All [the latest findings] suggest that the ancestor of all snakes was a terrestrial animal… which lived partially underground.”

Ichthyosaurs, why did they become extinct?


This video says about itself:

Prehistoric News: The Ichthyosaur Graveyard

23 June 2014

Dozens of nearly complete skeletons of ichthyosaurs have been uncovered near a melting glacier in southern Chile.

From LiveScience:

An Asteroid Didn’t Wipe Out Ichthyosaurs — So What Did?

by Laura Geggel, Staff Writer

July 23, 2015 08:05am ET

During the dinosaur age, ichthyosaurs — large marine reptiles that look like dolphins — flourished in prehistoric oceans, living in all kinds of watery environments near and far from shore. But as competition in these areas grew, ichthyosaurs lost both territory and species before gradually going extinct, a new study finds.

In fact, the ichthyosaur extinction has stumped scientists for years. Ichthyosaurs likely evolved from land reptiles that dove into the ocean about 248 million years ago, researchers said. After living along the coast for millions of years, they left for the open water. They disappeared about 90 million years ago, going extinct about 25 million years before the dinosaur-killing asteroid slammed into Earth.

So, if the asteroid didn’t kill the ichthyosaurs, what did? To learn more, researchers looked at ichthyosaur fossils and determined what kinds of specialized environments, or niches, the animals likely inhabited. [In Images: Graveyard of Ichthyosaur Fossils Found in Chile]

“In most studies, the niche of the animal is predicted based on a single trait, usually the shape of the teeth,” said lead researcher Daniel Dicks, a doctoral student in paleontology at the Natural History Museum in Stuttgart, Germany. In the new study, the researchers looked at several traits, he said.

For instance, they analyzed the ichthyosaurs’ body sizes and teeth shapes. They also determined each animal’s feeding strategy, such as whether ichthyosaurs were ambush predators (less powerful swimmers) or pursuit predators (fast swimmers), Dicks said.

Ichthyosaur arrangements

After examining 45 ichthyosaur genuses, Dicks and his colleague Erin Maxwell, a vertebrate paleontologist at the museum, used an analysis that grouped the ichthyosaurs into seven categories, called ecotypes.

For instance, the ichthyosauriform genus, Cartorhynchus, is so unique that it has its own ecotype. It was likely a small suction feeder and lived in shallow water, Dicks told Live Science.

Another ecotype represents the majority of the genuses that lived during the Early to Middle Triassic period, he said. Animals of this ecotype were less than 6.5 feet (2 meters) long, and had robust and blunt teeth, suggesting they ate hard-shelled prey, such as coral and shelled mollusks, Dicks said. They didn’t have elongated bodies, so they probably didn’t live in the open water, where they would have needed to swim far distances, he added.

Two genuses — Eurhinosaurus and Excalibosaurus — owe their unique ecotype to their swordfishlike jaws, which indicate they used a slashing method to demolish prey, Dicks said. Their long bodies also indicate they lived in the open water, far from shore, he said.

Not all seven ecotypes existed at once, although five existed simultaneously during the Early Jurassic period, when ichthyosaurs experienced a boom in diversity.

By the Middle Jurassic, the number of ichthyosaur ecotypes decreased. Specialized feeders, such as the swordfishlike Eurhinosaurus, and apex predators, including Temnodontosaurus, went extinct, leaving only two ecotypes, both of which lived in the open water.

These last two ecotypes included ichthyosaur genuses with large bodies and robust teeth for crushing bony fish or hard cephalopods, such as ammonites. The other ecotype was more dolphinlike; it had small teeth and likely ate soft prey, such as squid (also cephalopods), Dicks said.

Ichthyosaur extinction

Ichthyosaurs eventually met their end during the Cenomanian-Turonian extinction event, in which spinosaurs (carnivorous swimming dinosaurs), plesiosaurs (long-necked marine reptiles) and roughly one-third of marine invertebrates (animals without a backbone) also went extinct, Dicks said. [In Images: Digging Up a Swimming Dinosaur Called Spinosaurus]

With only two ecotypes of ichthyosaurs left, they would have been easily wiped out, Dicks said.

“It’s a slow ecological war of attrition, where they become more and more stranded on a single niche, and then the entire [group] is depending on that niche remaining sustainable,” he said. “And if that became unsustainable, then the entire group would become extinct.”

It’s unclear why ichthyosaurs lost their earlier niches, but they were likely “replaced, outcompeted by other species that adapted better,” Dicks said. For instance, plesiosaurs took over many of the near-shore niches, he said.

The study sheds light on ichthyosaurs’ evolution and extinction, said Neil Kelley, a postdoctoral research fellow of paleobiology at the National Museum of Natural History in Washington, D.C., who was not involved in the new research.

According to the study, “[ichthyosaurs] get more and more confined to a specialized lifestyle,” Kelley said. “Ultimately, they can never seem to re-evolve some of these more transitional lifestyles and body types that you see early on.”

However, the study takes a broad view encompassing roughly 158 million years, so it loses some nuance in how these animals lived and why they went extinct, Kelley told Live Science. Furthermore, “just one weird fossil could totally rewrite that picture of what happened,” by adding another ecotype, Kelley said.

The study was published online July 8 in the journal Biology Letters.

Boa constrictors don’t suffocate rats, new research


This video from the USA says about itself:

Myth Busted: How Boa Constrictors Kill

22 July 2015

New research disproves the long-held belief that boa constrictors kill by suffocating their prey. Researchers at Dickinson College found that the powerful snakes actually inflict a very different cause of death.

From the Journal of Experimental Biology:

Snake constriction rapidly induces circulatory arrest in rats

Received February 21, 2015.
Accepted May 8, 2015.

ABSTRACT

As legless predators, snakes are unique in their ability to immobilize and kill their prey through the process of constriction, and yet how this pressure incapacitates and ultimately kills the prey remains unknown. In this study, we examined the cardiovascular function of anesthetized rats before, during and after being constricted by boas (Boa constrictor) to examine the effect of constriction on the prey’s circulatory function. The results demonstrate that within 6 s of being constricted, peripheral arterial blood pressure (PBP) at the femoral artery dropped to 1/2 of baseline values while central venous pressure (CVP) increased 6-fold from baseline during the same time.

Electrocardiographic recordings from the anesthetized rat’s heart revealed profound bradycardia as heart rate (fH) dropped to nearly half of baseline within 60 s of being constricted, and QRS duration nearly doubled over the same time period. By the end of constriction (mean 6.5±1 min), rat PBP dropped 2.9-fold, fH dropped 3.9-fold, systemic perfusion pressure (SPP=PBP−CVP) dropped 5.7-fold, and 91% of rats (10 of 11) had evidence of cardiac electrical dysfunction. Blood drawn immediately after constriction revealed that, relative to baseline, rats were hyperkalemic (serum potassium levels nearly doubled) and acidotic (blood pH dropped from 7.4 to 7.0). These results are the first to document the physiological response of prey to constriction and support the hypothesis that snake constriction induces rapid prey death due to circulatory arrest.

Plesiosaur discovery in Alberta, Canada


Plesiosaur skeleton

In Alberta, Canada, a fossil plesiosaur from the Cretaceous age has been discovered in November 2011: here.

Talking about fossils: Oldest Hairy Microbe Fossils Discovered.

Swimming with snapping turtles, video


This video from Canada says about itself:

15 July 2015

Swimming with large snapping turtles in Parry Sound. When approached slowly, these creatures don’t show any aggression and almost no fear. These two were looking for food and checking out the camera as I swam around with them for hours.