Dinosaur extinction and bird evolution


This American Museum of Natural History video from the USA says about itself:

18 March 2016

This spellbinding animation from the Museum’s new exhibition “Dinosaurs Among Us” traces the evolutionary transition from dinosaurs to birds.

Based on recent scientific research that examines fossils using new technologies, the transformation story unfolds as low-polygonal silhouettes of dinosaurs morph from ground-dwelling animals into flight-capable birds. The mass extinction that erased most dinosaurs 65 million years ago left a few bird lineages unscathed. Within only 15 million years all of our familiar bird groups were flourishing. These extraordinary living dinosaurs provide a vivid link to the ancient past. The Museum’s new exhibition, “Dinosaurs Among Us,” explores the continuities between living dinosaurs—birds—and their extinct ancestors, showcasing remarkable new evidence for what scientists now call one of the best-documented evolutionary transitions in the history of life.

From Cornell University in the USA:

Dino-killing asteroid’s impact on bird evolution

September 21, 2017

Human activities could change the pace of evolution, similar to what occurred 66 million years ago when a giant asteroid wiped out the dinosaurs, leaving modern birds as their only descendants. That’s one conclusion drawn by the authors of a new study published in Systematic Biology.

Cornell University Ph.D. candidate Jacob Berv and University of Bath Prize Fellow Daniel Field suggest that the meteor-induced mass extinction (a.k.a. the K-Pg event) led to an acceleration in the rate of genetic evolution among its avian survivors. These survivors may have been much smaller than their pre-extinction relatives.

“There is good evidence that size reductions after mass extinctions may have occurred in many groups of organisms,” says Berv. “All of the new evidence we have reviewed is also consistent with a Lilliput Effect affecting birds across the K-Pg mass extinction.” Paleontologists have dubbed this phenomenon the “Lilliput Effect” — a nod to the classic tale Gulliver’s Travels.

“Smaller birds tend to have faster metabolic rates and shorter generation times,” Field explains. “Our hypothesis is that these important biological characters, which affect the rate of DNA evolution, may have been influenced by the K-Pg event.”

The researchers jumped into this line of inquiry because of the long-running “rocks and clocks” debate. Different studies often report substantial discrepancies between age estimates for groups of organisms implied by the fossil record and estimates generated by molecular clocks. Molecular clocks use the rate at which DNA sequences change to estimate how long ago new species arose, assuming a relatively steady rate of genetic evolution. But if the K-Pg extinction caused avian molecular clocks to temporarily speed up, Berv and Field say this could explain at least some of the mismatch. “Size reductions across the K-Pg extinction would be predicted to do exactly that,” says Berv.

“The bottom line is that, by speeding up avian genetic evolution, the K-Pg mass extinction may have temporarily altered the rate of the avian molecular clock,” says Field. “Similar processes may have influenced the evolution of many groups across this extinction event, like plants, mammals, and other forms of life.”

The authors suggest that human activity may even be driving a similar Lilliput-like pattern in the modern world, as more and more large animals go extinct because of hunting, habitat destruction, and climate change.

“Right now, the planet’s large animals are being decimated — the big cats, elephants, rhinos, and whales,” notes Berv. “We need to start thinking about conservation not just in terms of functional biodiversity loss, but about how our actions will affect the future of evolution itself.”

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Some herbivorous dinosaurs really omnivorous?


This 2012 video from the USA says about itself:

Maiasaura: Learn About Dinosaurs with World Book’s Professor Nick

Maiasaura was a large plant-eating dinosaur noted for its nesting behavior. Its name means good mother lizard, though dinosaurs were not lizards. Evidence suggests that its hatchlings were completely dependent on their parents for food and protection. Maiasaura lived about 75 to 80 million years ago in the area of what is now Montana. It belonged to a group known as duckbilled dinosaurs or hadrosaurids. These dinosaurs ate plants using a beak that somewhat resembled a duck’s bill.

By Carolyn Gramling, 9:00am, September 21, 2017:

Shhhh! Some plant-eating dinos snacked on crunchy critters

Crustacean shells discovered in fossilized poop reveal diet secrets of ancient herbivores

Some dinosaurs liked to cheat on their vegetarian diet.

Based on the shape of their teeth and jaws, large plant-eating dinosaurs are generally thought to have been exclusively herbivorous. But for one group of dinosaurs, roughly 75-million-year-old poop tells another story. Their fossilized droppings, or coprolites, contained tiny fragments of mollusk and other crustacean

Mollusks and crustaceans are two different groups.

shells along with an abundance of rotten wood, researchers report September 21 in Scientific Reports. Eating the crustaceans as well as the wood might have given the dinosaurs an extra dose of nutrients during breeding season to help form eggs and nourish the embryos.

“Living herd animals do occasionally turn carnivore to fulfill a particular nutritional need,” says vertebrate paleontologist Paul Barrett of the Natural History Museum in London. “Sheep and cows are known to eat carcasses or bone when they have a deficiency in a mineral such as phosphorus or calcium, or if they’re pregnant or ill.” But the discovery that some plant-eating dinos also ate crustaceans is the first example of this behavior in an extinct herbivore, says Barrett, who was not involved in the new study.

Ten years ago, paleoecologist Karen Chin of the University of Colorado Boulder described finding large pieces of rotted wood in dino dung. The coprolites were within a layer of rock in Montana, known as the Two Medicine Formation, dating to between 80 million and 74 million years ago. That layer also contained numerous fossils of Maiasaura, a type of large, herbivorous duck-billed dinosaur, or hadrosaur (SN: 8/9/14, p. 20).

Chin wondered whether the wood itself was the dino’s real dietary target. “The coprolites in Montana were associated with the nesting grounds of the Maiasaura,” she says. “I suspected that the dinosaurs were after insects in the wood. But I never found any insects in the coprolites there.”

Her hunch wasn’t too far off. Now she’s found evidence of some kind of crustaceans in dino poop. The new evidence comes from an 860-meter-thick layer of rock in Utah known as the Kaiparowits Formation, which dates to between 76.1 million and 74 million years ago. Ten of the 15 coprolites that Chin and her team examined contained tiny fragments of shell that were scattered throughout the dung. They were too small to identify by species, and may have been crabs, insects or some other type of shelled animal, Chin says. Based on the scattering of shell fragments, the animals were certainly eaten along with the wood rather than being later visitors to the dung heap.

Since bones from hadrosaurs are especially abundant in the Kaiparowits Formation, Chin suspects those kinds of dinos deposited the dung. Other large herbivores, such as three-horned ceratopsians and armored ankylosaurs, also roamed the area (SN: 6/24/17, p. 4).

The crustacean diet cheat may have been a seasonal event, related perhaps to breeding to obtain extra nutrients, Chin and colleagues say.

But how often — or why — the dinosaurs ate the shelled critters is hard to prove from the fossil dung alone, Barrett says. Herbivore coprolites are rare in the fossil record because a diet of leaves and other green plant material doesn’t leave a lot of hard material to preserve (unlike bones in carnivore dung). Coprolites with crustaceans, on the other hand, are more likely to get fossilized — and that preferential preservation might make it appear that this behavior was more frequent than it actually was. “These kinds of things give neat snapshots of specific behaviors that those animals are doing at any one time,” he adds. “But it’s difficult to build that into a bigger picture.”

Sea turtle conservation works


This video says about itself:

8 May 2012

In Malaysia there is an island known for more sea turtles than virtually anywhere on Earth. Jonathan visits this amazing ecosystem to learn about the life cycle of sea turtles. He is surprised to discover an amazingly complex and competitive environment.

From the American Association for the Advancement of Science in the USA:

Efforts to save sea turtles are a ‘global conservation success story’

September 20, 2017

A new study of the world’s seven sea turtle species provides evidence that their numbers are growing overall (unlike many endangered vertebrates), thanks to years of conservation efforts that have played a key role in sea turtle recovery — even for small sea turtle populations. Sea turtles have historically suffered population declines for reasons that include accidental catch and harvesting adults and eggs.

Such decreases have motivated worldwide conservation efforts since the 1950s to employ tactics like strict fishing regulations and beach protection measures. To examine the current global status of sea turtles, Antonios Mazaris and colleagues studied 4,417 annual estimates of sea turtle nesting abundance based on specific time periods of nesting data collection that ranged in length from six to 47 years.

They used estimates from 2010 or later to evaluate the length of time periods required to detect significant trends in abundance within Regional Management Units (which represent discrete groups of nesting sites in certain areas that are distinct from one another based on genetics, distribution, movement, and demography) for each species, finding a majority of population increases (95 significant increases compared to 35 significant decreases).

Despite the encouraging upward population trends, Mazaris et al.’s results complement International Union of Conservation for Nature (IUCN) assessments of sea turtle status, which lists six sea turtle species as endangered.

The authors also found that while longer time periods of nesting data collection are important for detecting population trends, shorter intervals not currently used by IUCN could still provide important information, though they highlight the need for more updated and continuous nesting site information.

Sauropod dinosaur evolution, new research


This video says about itself:

17 September 2015

“Saturnalia” is an extinct genus of basal sauropodomorph dinosaur known from the Triassic of Rio Grande do Sul, southern Brazil.

“Saturnalia” was originally named on the basis of three partial skeletons. The holotype, MCP 3844-PV, a well-preserved semi-articulated postcranial skeleton, was discovered in mid-summer at Sanga da Alemoa, Rio Grande do Sul, in Brazil, in the geopark of Paleorrota. The two paratypes are MCP 3845-PV, partial skeleton including natural cast of partial mandible with teeth and some postcranial remains, and MCP 3846-PV, partial skeleton including postcranial remains. All specimen were collected in the “Wald-Sanga” locality from the Alemoa Member of the Santa Maria Formation, dating to the Carnian faunal stage of the early Late Triassic, about 225 million years ago. A partial femur from the Carnian Pebbly Arkose Formation of Zimbabwe was also attributed to the genus. It is one of the oldest true dinosaurs yet found. It probably grew to about 1.5 meters long.

“Saturnalia” was first named by Max C. Langer, Fernando Abdala, Martha Richter, Michael J. Benton in 1999 and the type species is “Saturnalia tupiniquim“. The generic name is derived from “Saturnalia”, Latin for “Carnival“, in reference to the discovery of the paratypes during the feasting period. The specific name is derived from a Portuguese and Guarani word meaning “native”.

The primitive nature of “Saturnalia”, combined with its mixture of sauropodomorph and theropod characteristics, has made it difficult to classify. Paleontologist Max Cardoso Langer and colleagues, in their 1999 description of the genus, assigned it to the Sauropodomorpha. However, in a 2003 paper, Langer noted that features of its skull and hand were more similar to the sister group of sauropodomorphs, the theropods, and that “Saturnalia” could at best be considered a member of the sauropodomorph “stem-lineage”, rather than a true member of that group.

From the Ludwig-Maximilians-Universität München in Germany:

Dinosaur evolution: Lumbering giants had agile ancestors

September 20, 2017

The best known sauropod dinosaurs were huge herbivorous creatures, whose brain structures were markedly different from those of their evolutionary predecessors, for the earliest representatives of the group were small, lithe carnivores.

The sauropod group of dinosaurs included the largest animals that have ever walked the Earth — up to 40 meters long and weighing as much as 90 tons. Evolutionarily speaking, they were obviously very successful, giving rise to a diverse and widely distributed array of plant-eating species. These forms were characterized by a small head, a long and highly flexible neck that allowed them — like modern giraffes — to graze the tops of the tallest trees, and a massive body that made mature specimens invulnerable to predators. The sauropods survived for well over 100 million years before succumbing to the meteorite that snuffed out the dinosaurs at the end of the Cretaceous Era.

However, the early representatives of the lineage that led to these lumbering giants were strikingly different in form and habits. For a start, they were carnivores — like Saturnalia tupiniquim, an early sauropod dinosaur that was about the same size as a modern wolf. Recent work carried out by researchers for Ludwig-Maxilians-Universitaet (LMU) in Munich in collaboration with colleagues in Brazil now confirms this scenario and adds new details to the story. Most of the evidence for the early members of the Sauropodomorpha comes from their type of dentition. Now paleontologists Mario Bronzati and Oliver Rauhut, who are based at LMU and the Bavarian State Collection for Paleontology and Geology in Munich, have used computer tomography (CT) to analyze fossil skull bones assigned to S. tupiniquim. The high-resolution images of the cranial bones provided by this technique enabled them to deduce the overall surface morphology of the brain. The results suggest that despite being capable of consuming both meat and plants, S. tupiniquim could have followed a purely predatory lifestyle. The new findings appear in Scientific Reports.

The fossil material used in the study was discovered in Brazil over 20 years ago. It comes from a geological formation that dates back to the Triassic Era, and is about 230 million years old. According to the authors of the study, these are the oldest dinosaur bones that have been successfully reassembled with the aid of computer tomography at sufficiently high resolution to permit the reconstruction of the gross anatomy of the brain.

The evolution of the so-called Sauropodomorpha, of which Saturnalia tupiniquim is an early representative, and the Sauropoda sensu stricto, is marked by a clear tendency towards extension of the neck region, which is accompanied by reduction of the size of the skull — with a corresponding decrease in the volume of the brain — relative to the skeleton as a whole. Saturnalia tupiniquim stands at the beginning of this process. But the new study reveals that, unlike the case in the true sauropods, a specific area in the cerebellum, which encompasses the two lobes known as the flocculus and paraflocculus, is particularly prominent in the brain of S. tupiniquim. These structures are known to play an important role in controlling voluntary movements of the head and neck, and are involved in regulating the oculomotor system, which stabilizes the animal’s field of view.

Bronzati, Rauhut and their co-authors therefore argue that these features enabled S. tupiniquim to adopt a predatory lifestyle. Their findings strongly suggest that, in contrast to the true sauropods, it had a bipedal gait. Moreover, it was nimble enough to hunt, seize and kill its prey — thanks to its inferred ability to track moving objects with its eyes and to execute rapid movements of its head and neck in a coordinated and precise fashion. With the aid of CT-based reconstruction of the surface anatomy of the brain, the researchers now hope to retrace other stages in the evolution of the sauropodomorphs.

‘Prehistoric frog ate dinosaurs’


This 2014 video about Beelzebufo ampinga is called Prehistoric News : Devil Frog had Spikes and Armor.

From Sci-News.com:

Giant Prehistoric Frogs Ate Small Dinosaurs, Claim Scientists

Sep 20, 2017

Exceptionally large individuals of Beelzebufo ampinga, an extinct species of frog that lived in Madagascar during the Late Cretaceous epoch, about 68 million years ago, were capable of eating small dinosaurs, according to an international research team led by California State Polytechnic University scientists.

This conclusion comes from a study of the bite force of extant South American horned frogs (genus Ceratophrys).

“Unlike the vast majority of frogs which have weak jaws and typically consume small prey, horned frogs ambush animals as large as themselves — including other frogs, snakes, and rodents,” explained co-author Dr. Marc Jones, from the University of Adelaide and the South Australian Museum.

“And their powerful jaws play a critical role in grabbing and subduing the prey.”

Dr. Jones and co-authors from the United States, the United Kingdom, and Australia found that small horned frogs, with head width of about 1.8 inches (4.5 cm), can bite with a force of 30 newtons (N), or about 3 kg/6.6 lbs.

A scaling experiment, comparing bite force with head and body size, calculated that large horned frogs that are found in the tropical and subtropical moist lowland forests of South America, with a head width of up to 4 inches (10 cm), would have a bite force of almost 500 N. This is comparable to reptiles and mammals with a similar head size.

“This would feel like having 50 liters of water balanced on your fingertip,” explained lead author Professor Kristopher Lappin, of California State Polytechnic University.

“Many people find horned frogs hilarious because of their big heads and fat, round bodies,” said co-author Sean Wilcox, a PhD candidate at the University of California, Riverside.

“Yet, these predators have given us a rare opportunity to learn something more about the biology of a huge extinct frog.”

The team estimated the bite force of the extinct frog Beelzebufo ampinga may have had a bite up to 2,200 N, comparable to formidable mammalian predators such as wolves and female tigers.

“At this bite force, Beelzebufo ampinga would have been capable of subduing the small and juvenile dinosaurs that shared its environment,” Dr. Jones said.

“This is the first time bite force has been measured in a frog,” Professor Lappin said.

“And, speaking from experience, horned frogs have quite an impressive bite, and they tend not to let go.”

“The bite of a large Beelzebufo ampinga would have been remarkable, definitely not something I would want to experience firsthand.”

The study appears today in the journal Scientific Reports.

Impala escapes from crocodile


This video from Maasai Mara national park in Kenya says about itself:

12 September 2017

Impala miraculously escapes from the deadly jaws of a crocodile.

Rattlesnake slow motion video


This 8 September 2017 video is called Rattlesnake Tail In Slow Motion – BBC Earth.