5 years ago: 50 million year-old lizard skin. @sidperkins @sciencemagazine.
"...Discovered in the 1980s, the lizard fossil is one of only two known examples of reptile skin unearthed from the Green River Formation of the western United States, a finely layered mudstone best known for its exquisite fish fossils. Even though soft tissues are incredibly rare in the fossil record, being preserved only in unusual environmental circumstances, this lizard fossil survived the ages, says Phillip Manning, a vertebrate paleontologist at the University of Manchester in the United Kingdom. It's easy to see the remnants of individual scales in the skin, but the rock doesn't include any visible remains of bones or other hard tissue—a combination that led researchers to believe that the skin had been shed by a living creature and then preserved.
But recently, to learn more about the fossil, Manning and his colleagues turned to a relatively new x-ray analysis technique—dubbed synchrotron rapid scanning x-ray fluorescence—with surprising results. Instead of enabling scientists to see inside or through rock, he notes, the intense x-rays produced by this technique cause particular elements or compounds to fluoresce, revealing previously unrecognized chemical remnants that are invisible to the naked eye but persist in the rocks at very low concentrations.
When the researchers illuminated the fossil with x-rays that cause sulfur and copper to fluoresce, the skin remnants showed up in remarkable detail. But when they lit the fossil with x-rays that cause phosphorus to glow, the technique revealed many small spots in the lizard's head where that element was concentrated—regularly spaced spots that appear where the creature's jaws would have been. The arrangement prompted the researchers to interpret the traces of phosphorus as the chemical remnants of teeth. Because lizards don't shed their teeth when they molt their skin, the technique reveals the unusual fossil to be the partially preserved remnants of a full carcass, the researchers report online this month in Applied Physics A: Materials Science & Processing.
The fossil's state of preservation reveals a lot about the environmental conditions where the carcass ended up, presumably after being washed into the lake soon after it died. Lake-bottom waters at this particular spot likely had little or no oxygen, enabling preservation of the skin. But the waters apparently were also acidic, which totally dissolved the creature's bones and left only scant traces of its teeth. The chemical vestiges of the teeth were most likely preserved because tooth enamel typically has a low concentration of organic matter and large crystals of phosphate minerals, both of which render the teeth more resistant to decay.
The x-ray technique the team used "will open the curtain to a whole new way of studying extinct animals and the conditions in which they lived and died," Manning says. Another benefit of the approach, he notes, is that it's nondestructive...."
Arachnophobes, go to your happy place and please click here. Researchers from the San Diego Natural History Museum along with other experts recently unveiled a new spider species found in Mexico that is roughly the size of a softball, reports Deborah Sullivan Brennan at the Los Angeles Times.
According to a blog post from the museum, in 2013 field entomologist Jim Berrian and a team of researchers found the spider while exploring the Sierra Cacachilas, a small mountain range in Baja California Sur in Mexico. Investigating a cave in the area, they noticed a giant exoskeleton hanging from the ceiling. Instead of running back to their hotel and hiding under the covers, they decided to return that night, since they identified the spider as belonging to a genus of arachnids that are often nocturnal. That night, in the darkened cave, the team got their first look at what is now known as Califorctenus cacachilensis, or the Sierra Cacachilas wandering spider. The official description of the new spider appears in the journal Zootaxa.
“When I saw these spiders for the first time, I was very impressed by their size,” Baja spider expert Maria Luisa Jimenez, a researcher at Centro de Investigaciones Biológicas del Noroeste, says in the blog post. “In all my experience over the years collecting spiders on the peninsula, I had never seen a spider this large. I suspected that something new was waiting to be described.”
Read more: SMITHSONIAN
Wolf in dog's clothing. @jamesgorman
"The history of dogs is still murky, however, because it seems that different kinds of wolves and dogs have interbred at different times in different places over the past tens of thousands of years.
Love Dalen, of the Swedish Museum of Natural History and an author of the report in Current Biology, said that the simplest explanation for the new evidence “is that dogs were domesticated as much as 30,000 years ago.”
But, he said, the researchers’ work does not prove that this is what happened. Pontus Skoglund, a research fellow at Harvard University and the first author of the research paper, said, “We can’t just look at the DNA and say whether a canid was living with modern humans.”
Phys.org)—Stephen Brusatte, a fellow in Vertebrate Paleontology at the University of Edinburgh in the U.K. has published a Perspective piece in the journal Science outlining the state of current research into the development of flight in dinosaurs. In it, he suggests that contrary to common assumptions, it appears that the path to flight for dinosaurs was anything but a straight line.
As Brusatte notes, when most people think of the evolution of a particular feature or ability, they tend to think of a straight line—a species develops a feature that allows it to do something better; its offspring also express that feature, and soon another feature is added until something like wings for flight develop...."
Read more at: https://phys.org/news/2017-02-paleontologist-path-flight-dinosaurs-straight.html#jCp
—Stephen Louis Brusatte, paleontologist and evolutionary biologist specializing in the anatomy and evolution of dinosaurs.
"A 245-million-year-old fossil of a pregnant reptile offers the first evidence for live birth in the animal group that includes modern birds and crocodiles.
Live birth has evolved dozens of times in vertebrates, but has never been seen in archosauromorphs, which emerged around 260 million years ago. This group comprises dinosaurs as well as extant birds and crocodiles.
A team led by Jun Liu at the Hefei University of Technology in China analysed the fossil — found in 2008 in southwestern China — and concluded that it was a long-necked marine reptile called Dinocephalosaurus. A relatively large creature found inside its rib cage was curled up and positioned in a way that is typical of vertebrate embryos.
The fossil suggests that no genetic or developmental barriers prevented live births in archosauromorphs, the authors say."
In expeditions to the Gobi Desert in the past decade, Lee and his colleagues have unearthed the 70-million-year-old fossils of two more individuals of the species from sites near to where the original 1965 specimen was discovered. Together, those remains — along with some bones stolen by poachers before Lee and his team found the fossils, but since recovered from a private collection — account for about 95% of the creature’s skeleton, he notes.
The newer-found bones differ from those of other ornithomimosaurs in several unexpected ways. Most of the spinal vertebrae have blade-like projections that extended upward and served as anchors for a network of ligaments that probably helped to support the immense weight of the creature’s abdomen. The researchers estimate that Deinocheirus was about 11 metres long and tipped the scales at more than 6.3 tonnes.
“This is definitely an unusual animal,” says Thomas Holtz, Jr., a vertebrate palaeontologist at the University of Maryland in College Park, who wrote an accompanying News & Views piece2. “It had more of a ‘beer belly’ than your typical ornithomimosaur,” he suggests...."