Fossil otter discovery in Mexico


This video says about itself:

28 February 2017

Researchers have uncovered the remains of a giant otter in China that when alive would have been comparable to the size of a wolf.

The fossils belong to a new species of ancient otter, known as Siamogale melilutra, that lived in freshwater lakes around 6 million years ago.

From the University at Buffalo in the USA:

Ancient otter tooth found in Mexico suggests mammals migrated across America

June 14, 2017

Summary: An ancient otter tooth recently discovered in Mexico suggests certain mammals migrated across America during the Miocene geologic epoch, roughly 23 million to 5.3 million years ago. The new hypothesized route questions other theories such as migrations above Canada and through Panama, and has implications for a much larger biologic event — the Great American Biotic Interchange, when land bridges were formed and animals dispersed to and from North America and South America.

Late in the afternoon on a hot March day in central Mexico, a paleontologist uncovered a jaw bone and called over to Jack Tseng.

Tseng, PhD, assistant professor in the Department of Pathology and Anatomical Sciences in the Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, was on the dig researching intercontinental immigration of fossil mammals.

“I thought it was a badger,” Tseng said, “but a colleague on the site had just finished a study of otters, and he said it was sea otter-like. But what would a sea otter be doing in central Mexico?”

Turns out the otter, from about 6 million years ago, may have been part of an immigration event from Florida to California. Based on the discovery, Tseng and his colleagues have written a paper to be published June 13 in the journal Biology Letters. They propose a new east-west passage for the otter, and potentially other mammals, along the northern edge of the Trans-Mexican Volcanic Belt, which runs across the country at the latitude of Mexico City.

“This is an entirely new idea that no one else has proposed,” Tseng said. “We think it’s very likely other animals utilized this route.”

The right tooth

Like many breakthroughs, this one came from a fortunate tiny detail. The jawbone held several teeth.

“One tooth was a lower first molar, the most diagnostic tooth in a carnivore,” Tseng said. “If we are lucky enough to find a fossil molar tooth that is complete, there is a lot of useful information.”

The tooth was almost identical to a tooth from another Enhydritherium terraenovae (an ancient sea otter) fossil found in Florida. Similar finds had only been made along the coasts, in Florida and California, but paleontologists did not know how the animals got across the continent. One hypothesis was that they moved up and around through northern Canada, an 8,000 kilometer trip. Another was they made it down to Panama and crossed over to the west.

The possibility of an east-west migratory route in Mexico in the Miocene geologic epoch (roughly 23 million to 5.3 million years ago) has implications for a much larger biologic event — the Great American Biotic Interchange, when land bridges were formed and animals dispersed to and from North America and South America. It shows that the region’s fossil sites could have recorded details of this biological interchange of historic proportions.

But why don’t we know more about this already?

“Compared to the U.S., Mexico is a blank slate in terms of paleontology,” Tseng said. The region is difficult to work in because of the topography and flora, like cactus. So not many long-term field projects exist there.

“This is the beginning of the study,” Tseng said. “Now that we have this evidence of these animals moving through Mexico, we can now look for evidence of other animals doing the same.”

Expanding ranges

Adolfo Pacheco-Castro, a PhD student at the Universidad Nacional Autonoma de Mexico, Centro de Geociencias, and an author of the study, found the jawbone at the dig site in the Juchipila Basin, about 535 miles southeast of Laredo, Texas. The bone was taken to the university in Mexico, cleaned off and studied.

“We compared it to the original tooth from Florida, based on the cusps and the size, it couldn’t be anything else,” Tseng said. The fossils in Florida are older than those in California, so researchers speculate that immigrations went east to west.

But why did they travel at all?

“Animals tend to expand their range when and where there is opportunity,” Tseng said. “As in when there is a geographic connection to suitable habitats. So as populations expand their range, they can move across a continent, or even between continents.”

The Miocene-Pliocene transitional period was a time of disturbance, Tseng said. The plains of America would have been like Africa, with many large mammals. But the first ice age was approaching.

Many large mammals perished in the ice age from environmental and anthropogenic causes, but relatives of the smaller Enhydritherium — about the size of a small to medium dog — survived into modern times and still live around central Mexico today.

New area of study

Tseng said he expects some people will not agree with the new interpretation of an east-west corridor through Mexico for other mammals. But more research may confirm it.

“We are aware it is a single discovery,” he said. “It essentially opens up a can of worms. We are throwing a different factor in. We now have a connection between Florida and California, and it’s not in a straight line.”

Fossil marsupials discovery in Bolivia


This video says about itself:

24 April 2015

The Evolution Of Mammals

Description: The word “mammal” is modern, from the scientific name Mammalia coined by Carl Linnaeus in 1758, derived from the Latin mamma (“teat, pap”). All female mammals nurse their young with milk, which is secreted from special glands, the mammary glands.

According to Mammal Species of the World, 5,416 species were known in 2006. These were grouped in 1,229 genera, 153 families and 29 orders.[1] In 2008 the IUCN completed a five-year, 1,700-scientist Global Mammal Assessment for its IUCN Red List, which counted 5,488 accepted species at the end of that period.[2] In some classifications, the mammals are divided into two subclasses (not counting fossils): the Prototheria (order of Monotremata) and the Theria, the latter composed of the infraclasses Metatheria and Eutheria. The marsupials constitute the crown group of the Metatheria and therefore include all living metatherians as well as many extinct ones; the placentals likewise constitute the crown group of the Eutheria.

From Case Western Reserve University in the USA:

Three new species of extinct South American marsupials discovered

Findings show the family, Palaeothentidae, was once widespread across the continent but add to extinction doubts

April 11, 2017

The discovery of three extinct species and new insights to a fourth indicates a little-known family of marsupials, the Palaeothentidae, was diverse and existed over a wide range of South America as recent as 13 million years ago. Fossils of the new species were found at Quebrada Honda, a high elevation fossil site in southern Bolivia, and are among the youngest known palaeothentid fossils.

The discovery of three extinct species and new insights to a fourth indicates a little-known family of marsupials, the Palaeothentidae, was diverse and existed over a wide range of South America as recent as 13 million years ago.

The finding, however, complicates the question: why did these animals go extinct?

“It was previously assumed this group slowly went extinct over a long time period, but that’s probably not the case,” said Russell Engelman, a biology MS student at Case Western Reserve and lead author of a new study on the group. “They were doing very well at the time they were supposedly on death’s door.”

Discovering new fossil sites may be the only way to learn the answer, researchers say.

Engelman; along with Federico Anaya, professor of geological engineering at Universidad Autónoma Tomás Frías, in Potosí, Bolivia; and Darin Croft, anatomy professor at Case Western Reserve School of Medicine, describe the animals, where they fit in the family, and their paleoecology and paleobiology in the Journal of Systematic Palaeontology.

Fossils of the new species were found at Quebrada Honda, a high elevation fossil site in southern Bolivia. They are about 13 million years old (from the middle Miocene epoch), placing them among the youngest known palaeothentid fossils.

Fossil remains of other members of the family, and other relatives within the order Paucituberculata, have been found at sites of similar age in southwestern Colombia and possibly southern Argentina, geographically spanning almost the entire continent.

“The only close relatives of palaeothentids alive today are shrew opossums, small, poorly-known, ground-living marsupials that live in and near the Andes,” Croft said. “Palaeothentid marsupials once included a diversity of species that filled a variety of roles in ancient ecosystems. During their heyday in the Miocene, they were abundant.”

The new species, Palaeothentes serratus, Palaeothentes relictus, and Chimeralestes ambiguus, all had long snouts but differed in diet and body size and other features.

The researchers suggest P. serratus — serratus means saw-like — was an insectivore, with well-developed slicing premolars. The researchers estimate the mouse-size marsupial weighed about 3.5 ounces.

P. relictus had large, well-developed grinding molars. The animal probably ate fruits, seeds and insects, and weighed about five ounces.

C. ambiguus, as the name indicates, has attributes of a number of family members, making its evolutionary relationships with the group uncertain. The animal was about the same size as P. serratus and its limited dental remains indicate its diet was likely similar to that of P. relictus.

The most common member of the family found at Quebrada Honda is Acdestis maddeni. The species was named 14 years ago, but the researchers are the first to find and analyze its lower jaw.

These lower jaw fossils, combined with reexamination of other specimens, show that the skull of Acdestis was different from other palaeothentids. A. maddeni’s snout is short and its canines are relatively large, followed by large, shearing middle teeth and molars well developed for grinding.

“All this indicates it was a generalist,” Engelman said. “Although it could eat fruits and insects like its relatives it could also catch small vertebrates and dismember them… It probably ate anything, like a hedgehog or Norway rat does.”

The animal was rat-size and weighed about a pound, the researchers estimate.

The fossil record indicates the Palaeothentidae and much of the order Paucituberculata abruptly went extinct about 12 million years ago, leaving only the lineage leading to modern shrew-opossums.

“Most species threatened with extinction are like giant pandas: highly specialized, live only in a certain area and eat only certain things,” Engelman said. Due to their diversity and wide range, “the Palaeothentidae didn’t fit the pattern of extinction.”

Previous hypotheses that palaeothentids were done in by climate change or competition lack support, the researchers say.

For example, fossils found at high latitudes in Argentina and Bolivia after the Middle Miocene Climatic Optimum indicate they withstood the dramatic cooling of the period. The family and opossums, which may have been competitors, appear to have overlapped for nearly 10 million years. Yet opossums didn’t become abundant until 3 million to 4 million years after the family went extinct.

But, the hypothesis cannot be completely ruled out, the researchers said. And, there is a possibility the decline of the family was slow.

The reason for the quandary is that fossils have been well collected in the southern end of South America but the middle and northern parts of the continent remain largely unexplored.

“It’s as if all the fossils in the U.S. came from Florida — you don’t get the full picture,” Engelman said.

If new fossil sites are found in the northern two-thirds of the continent, “it will be interesting to see whether we find younger members of the group,” Croft said. “That will help us understand their extinction.”

Ancient primate fossil discovery in India


This 2014 video Lecture 16 Early Primate Evolution.

From the University of Southern California in the USA:

Newfound primate teeth take a big bite out of the evolutionary tree of life

The new species of primate from India is distantly related to the lemurs of Madagascar

February 28, 2017

Summary:

Fossil hunters have found part of an ancient primate jawbone related to lemurs — the primitive primate group distantly connected to monkeys, apes and humans, a researcher reports. Scientists named the new species Ramadapis sahnii and said that it existed 11 to 14 million years ago. It is a member of the ancient Sivaladapidae primate family, consumed leaves and was about the size of a house cat.

Fossil hunters have found part of an ancient primate jawbone related to lemurs — the primitive primate group distantly connected to monkeys, apes and humans, a USC researcher said.

Biren Patel, an associate professor of clinical cell and neurobiology at the Keck School of Medicine of USC, has been digging for fossils in a paleontologically rich area of Kashmir in northern India for six years. Although paleontologists have scoured this region for a century, relics of small extinct primates were rarely found or studied.

Scientists named the new species Ramadapis sahnii and said that it existed 11 to 14 million years ago. It is a member of the ancient Sivaladapidae primate family, consumed leaves and was about the size of a house cat, said Patel, co-author of the new study in the Journal of Human Evolution.

“Among the primates, the most common ones in the Kashmir region are from a genus called Sivapithecus, which were ancestral forms of orangutans,” Patel said. “The fossil we found is from a different group on the primate family tree — one that is poorly known in Asia. We are filling an ecological and biogeographical gap that wasn’t really well documented. Every little step adds to the understanding of our human family tree because we’re also primates.”

The last primate found in the area was 38 years ago. So, in addition to being a new species, this is the first primate fossil found in the area in decades.

“In the past, people were interested in searching for big things — things they could show off to other people,” Patel said. “A lot of the small fossils were not on their radar.”

The inch-and-a-quarter partial mandible belongs to a primate weighing less than 11 pounds that had outlived its other adapidae cousins found in North America, Europe and Africa by millions of years.

“New primates are always a hot topic, and this one is the first of its kind from its area in Asia, which has significant consequences for understanding primate evolution in the Old World,” said Michael Habib, an assistant professor of clinical cell and neurobiology at the Keck School of Medicine who was not involved in the study.

The question that remains is how the ecosystem in northern India supported this species when its relatives elsewhere were disappearing or had already gone extinct. Future fieldwork and recovering more fossil primates will help answer this question.

“People want to know about human origins, but to fully understand human origins, you need to understand all of primate origins, including the lemurs and these Sivaladapids,” Patel said. “Lemurs and sivaladapids are sister groups to what we are — the anthropoids — and we are all primates.”

Researchers from Hunter College of the City University of New York, New York Consortium in Evolutionary Primatology, Arizona State University, Stony Brook University and Panjab University also contributed to this study, which was supported by the Wenner-Gren Foundation, the American Association of Physical Anthropologists, the Institute of Human Origins and funding from some of the involved universities.

Giant otter fossil discovery in China


This video from the USA says about itself:

23 January 2017

Dr. Denise Su, curator of paleobotany and paleoecology at The Cleveland Museum of Natural History, discusses the discovery of a new species of prehistoric otter, named Siamogale melilutra.

From Science News:

Ancient otter of unusual size unearthed in China

by Meghan Rosen

5:13pm, January 24, 2017

Fossils of a giant otter have emerged from the depths of an open-pit mine in China.

The crushed cranium, jaw bone and partial skeletons of at least three animals belong to a now-extinct species of otter that lived some 6.2 million years ago, scientists report January 23 in the Journal of Systematic Palaeontology.

At roughly 50 kilograms in weight, the otter would have outclassed today’s giant otter, a river-dwelling South American mammal weighing in at around 34 kilograms. Scientists named the new species Siamogale melilutra, a nod to its unusual mix of badger and otter features. Melilutra is a mash-up of the Latin words for both creatures.

Badgers and otters both belong to a group of carnivorous animals called Mustelidae, but scientists have had trouble figuring out where to place extinct members in the mammalian family tree. (European badgers and modern otters share similar-looking teeth and skulls.) Still, Siamogale melilutra, however badgerlike, is indeed an otter, researchers concluded after CT scanning, reconstructing and analyzing the fossil skull.

Based on plant and animal fossils found near the collection site, scientists believe that the ancient otter probably lived in the shallow lake of a warm and humid swamp, lush with broad-leaved evergreens and grasses.

New snake species discovery in India


This video says about itself:

The Incredible Indian Snake Girl

Deadly cobra snakes are the best pals of this eight-year-old Indian girl even after being bitten by them a couple of times. Kajol Khan who wants to become a snake catcher like her father eats, sleeps and plays with six cobras all day long. She has even stopped going to school out of her love for the snakes. Kajol said: “I didn’t like the company of humans in the school so stopped going there five years ago.” See how little girl Kajol plays with the deadly cobra snakes, trains the snakes and handles the snakes.

Now, from venomous to non-venomous snakes.

Wallaceophis gujaratenesis. Photo by Zeeshan Mirza

From PLOS ONE:

A New Miocene-Divergent Lineage of Old World Racer Snake from India

March 2, 2016

Abstract

A distinctive early Miocene-divergent lineage of Old world racer snakes is described as a new genus and species based on three specimens collected from the western Indian state of Gujarat. Wallaceophis gen. et. gujaratenesis sp. nov. is a member of a clade of old world racers.

The monotypic genus represents a distinct lineage among old world racers is recovered as a sister taxa to Lytorhynchus based on ~3047bp of combined nuclear (cmos) and mitochondrial molecular data (cytb, ND4, 12s, 16s). The snake is distinct morphologically in having a unique dorsal scale reduction formula not reported from any known colubrid snake genus. Uncorrected pairwise sequence divergence for nuclear gene cmos between Wallaceophis gen. et. gujaratenesis sp. nov. other members of the clade containing old world racers and whip snakes is 21–36%.

From IANS news in India:

Mumbai, March 3: A team of young Indian researchers and naturalists have recently discovered a new snake genus and species in Gujarat, it was announced here on Thursday.

The snake genus has been named Wallaceophis in honour of the legendary 19th century British naturalist Alfred Russel Wallace (1823-1913), considered the father of biogeography, while the snake species has been named gujaratenisis to commemorate the western Indian state where it was discovered.

Ancestors of New Zealand bats’ fossil discovery


This video says about itself:

Suzanne Hand: Miocene Fossils Reveal Ancient Roots for New Zealand’s Endemic Mystacina (Chiroptera)

26 June 2015

Dr Hand talks to Sciencevideos.org about her recent PLOS ONE publication: Miocene Fossils Reveal Ancient Roots for New Zealand’s Endemic Mystacina (Chiroptera) and Its Rainforest Habitat.

Giraffe ancestry, new research


This video is about giraffes in Africa.

From Science journal:

Odd creature was ancient ancestor of today’s giraffes

By Sid Perkins

24 November 2015 7:15 pm

A distant relative of today’s giraffes was a bit of an odd creature: It was about the size of a bull moose, but it had a long neck that could stretch both up to eat tree leaves and down to eat grass. That’s the conclusion of the first comprehensive analysis of a complete set of fossilized neck bones from the animal, known as Samotherium major. Samotherium, which lived in the open woodlands of Eurasia about 7 million years ago, had a neck about 1 meter long—about half the length of that of today’s giraffes. (And like the vast majority of mammals, from tiny mice to towering giraffes, it had seven neck vertebrae.)

Some scientists have long presumed today’s giraffe (Giraffa camelopardalis), which includes a handful of subspecies scattered throughout sub-Saharan Africa, evolved from an animal that looked like its close cousin the okapi (Okapia johnstoni), which lives in the tropical forests of central Africa. The team’s analyses of bones from all three animals bolster that notion—and not just because the neck bones are of a length between the giraffe’s and the okapi’s. For example, ridges and other features that are prominent on the okapi’s neck bones and missing entirely on the giraffe’s are typically present but smaller on Samotherium’s, the researchers report online today in Royal Society Open Science.

See also here.

Mysterious skin disease make giraffes vulnerable to lions: here.