fauna

Killer Cave Lured Ancient Carnivores to Their Death

by Tia Ghose

A cavern in Spain may have lured ancient carnivores to their deaths by offering the promise of food and water, new research suggests.

The new study, published today (May 1) in the journal PLOS ONE, may explain how the carcasses of several carnivore species, including saber-toothed cats and “bear dogs,” wound up in an underground cavern millions of years ago.

“Only the carnivores were daring enough to enter,” said study co-author M. Soledad Domingo, a paleontologist at the University of Michigan. “But they were unable to make their way out.”…

(read more: Live Science)

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(images: 1 - illustration of sabertooths with rhino in ancient cave by Mauricio Anton; 2 - photo of Sabertooth skull by Soledad Domingo; 3 - illustration of cave history by Anton, Domingo, Sanchez; 4 - fossil skeleton of ancient “Bear-Dog” by ghedoghedo | Wikimedia)

How Did the Largest Dinosaurs Grow Such Long Necks?

by Charles Choi

How did the largest of all dinosaurs evolve necks longer than any other creature that has ever lived? One secret: mostly hollow neck bones, researchers say.

The largest creatures to ever walk the Earth were the long-necked, long-tailed dinosaurs known as the sauropods. These vegetarians had by far the longest necks of any known animal. The dinosaurs’ necks reached up to 50 feet (15 meters) in length, six times longer than that of the current world-record holder, the giraffe, and at least five times longer than those of any other animal that has lived on land.

“They were really stupidly, absurdly oversized,” said researcher Michael Taylor, a vertebrate paleontologist at the University of Bristol in England. “In our feeble, modern world, we’re used to thinking of elephants as big, but sauropods reached 10 times the size elephants do. They were the size of walking whales.”

To find out how sauropod necks could get so long, scientists analyzed other long-necked creatures and compared sauropod anatomy with that of the dinosaurs’ nearest living relatives, the birds and crocodilians…

(read more: Live Science)          

(images: T - Alamosaurus by Dmitry Bogdanov; Bttm 3 - Taylor, Weddel 2013)

Longisquama

… is an extinct genus of lizard-like reptile. There is only one species, Longisquama insignis, known from a poorly preserved skeleton and several incomplete fossil impressions from the Middle to Late Triassic Madygen Formation in Kyrgyzstan.

Longisquama means “long scales”; the specific name insignis refers to its small size. The Longisquama holotype is notable for a number of long structures that appear to grow from its skin. These structures have been interpreted as either primitive feathers suggesting Longisquama is a close relative of birds, or as feather-like structures that have evolved independently and do not indicate a close relationship with birds.

Longisquama has been used in a heavily publicized debate on of the origin of birds. To some, Longisquama is the gliding, cold-blooded, protobird predicted by Gerhard Heilmann’s hypothetical “Proavis” in 1927, and it proves that birds are not dinosaurs. The current opinion is that Longisquama is an ambiguous diapsid and has no bearing on the origin of birds…

(read more: Wikipedia)                 (images: T - Nobu Tamura; B - Qilong)

The Paleo-Diet: Dinosaurs Lose Weight in New Study

by Charles Choi

The fact that bones have curves has now thrown a curveball into calculations of dinosaur weight, researchers say.

New estimates suggest dinosaurs may have been lighter than once thought, scientists explain.

With the rare exceptions of fossilized scraps of skin, feathers, bristles and other relatively soft tissues, all that remains of most extinct creatures are their skeletons. One way that investigators seek to learn more about these lost animals is to deduce their weight from their bones.

Traditionally, researchers would calculate estimates of dinosaur mass using a leg measurement such as the circumference of leg bones, understanding the relationship between body mass and this circumference in modern animals, “and scaling this up to the size of a dinosaur,” said researcher Charlotte Brassey, a biomechanist at the University of Manchester in England…

(read more: Live Science)             

(images: T - Bill Sellers; B - Charlotte Brassey)

Entelodonts - “Hell Pigs”

Entelodonts, sometimes nicknamed “hell pigs” or “terminator pigs”, are an extinct family of pig-like omnivores endemic to forests and plains of North America, Europe, and Asia from the middle Eocene to early Miocene epochs (37.2—16.3 mya), existing for approx 20.9 million years.

The largest were the North American Daeodon shoshonensis, the Entelodon and the Eurasian Paraentelodon intermedium, standing up to 2.1 m (6.9 ft) tall at-shoulder, with brains the size of an orange. A single specimen was recorded for body mass and was estimated to have a weight of 421 kg (930 lb). Their teeth suggest an omnivorous diet, similar to that of modern pigs. Like many other artiodactyls, they had cloven hooves, with two toes touching the ground, and the remaining two being vestigial.

Entelodonts lived in the forests and plains where they were the apex predators of North America’s Early Miocene and Oligocene, consuming carrion and live animals and rounding off their diet with plants and tubers. They would have hunted large animals dispatching them with a blow from their jaws. Some fossil remains of these other animals have been found with the bite marks of entelodonts on them. Like modern day pigs, they were omnivores, eating both meat and plants, but their adaptations show a bias towards live prey and carrion…

(read more: Wikipedia) 

(images: T - Elotherium by Heinrich Harder, 1920; ML - skull of Archaeotherium by H. Zell; MR - Archaeotherium by Robert Bruce Horsfall, 1913; BL -  Daeodon by Jay Materness, Smithsonian mural, 1964; Daeodon skeleton)

Andrewsarchus

Andrewsarchus mongoliensis was a mammal that lived during the Eocene epoch, roughly 45 - 36 million years ago. It had a long snout with large, sharp teeth and flat cheek teeth that may have been used to crush bones. Because Andrewsarchus is only known from a single skull, whether it was an active predator or a large scavenger is open to debate, as is its exact time range.

Andrewsarchus is named for the famous explorer and fossil hunter Roy Chapman Andrews. It was discovered in June 1923 by Kan Chuen Pao, a member of Andrews’ expedition, at a site in the Gobi Desert in Mongolia known as Irdin Manha on the third Asiatic expedition that was led by Andrews and sponsored by the American Museum of Natural History. The skull is now on display at the American Museum of Natural History in New York; the lower jaw was not found.

It was classified in the clade Mesonychia due to the similarity in structure between its teeth and skull with those of other mesonychid species known from complete skeleton, however, much of this was based only on Osborn’s original publication, and more recent studies have found it to have no special mesonychid affinities, instead grouping with various artiodactyl clades. Indeed one study (Spaulding et al.) has not only found them to be closer to entelodonts (“Hell Pigs”), but as kin to Cetancodonta (cetaceans and hippos)…

(read more: Wikipedia)

(images: TL - Dmitri Bogdanov; TR - US Gov; B - Ryan Somma)

Placodus

… (meaning ‘flat tooth’) was a genus of marine reptiles, belonging to the order Placodontia, which swam in the shallow seas of the middle Triassic period (ca. 240 million years ago). Fossils of Placodus have been found in Central Europe (Germany, France, Poland) and China.

Placodus had a stocky body with a long tail, and reached a total length of up to 2 m (6.6 ft). It had a short neck, and a heavy skull. They were specialized for a durophagous diet of shellfish, such as bivalves. Chisel-like incisors protruded from the anterior margin of the snout, and were probably used to pluck hard-shelled benthic prey from the substrate. The back teeth were broad and flattened, and would have helped to crush the prey.Before the animals’ anatomy was known, they were regarded as fishes’ teeth. Similar smaller teeth were present on the palatine bones…

(read more: Wikipedia)     

(images: T - Placodus gigas by Nobu Tamura; BL - H. Alleyne Nicholson, 1976 ; BR - Ghedoghedo)

Diprotodon

… (meaning “two forward teeth”), sometimes known as the giant wombat or the rhinoceros wombat, is the largest known marsupial ever to have lived. Along with many other members of a group of unusual species collectively called the “Australian megafauna”, it existed from approximately 1.6 million years ago until extinction some 46,000 years ago (through most of the Pleistocene epoch).

Diprotodon fossils have been found in sites across mainland Australia, including complete skulls and skeletons, as well as hair and foot impressions. Female skeletons have been found with babies located where the mother’s pouch would have been. The largest specimens were hippopotamus-sized: about 3 m(10 ft) from nose to tail, standing 2 m (6.6 ft) tall at the shoulder and weighing up to 2,800 kg (6,200 lb). They inhabited open forest, woodlands, and grasslands, possibly staying close to water, and eating leaves, shrubs, and some grasses…

(read more: Wikipedia)

(images: TL - Dmitry Bogdanov; TR - Kevmin; BL - Erich Schulz; BR - Nobu Tamura)

Polacanthus 

… was an armored, spiked, plant-eating ankylosaur from the early Cretaceous period. Early depictions often gave it a very vague head as it was only known from the rear half of the creature. It lived 130 to 125 million years ago in what is now western Europe. Polacanthus grew to between 4 to 5 m (13 to 16 ft) long. There are not many fossil remains of this creature, and some important anatomical features, such as its skull, are poorly known. Polacanthus had a large sacral shield, a single fused sheet of dermal bone over its hips (sacral area) which was not attached to the underlying bone and decorated with tubercles…

(read more: Wikipedia)          (images: T - FunkMonk; B - Baron Nopsca, 1933)