How sea snakes avoid predators


This 2015 video says about itself:

Many people don’t realize that there are snakes that live in the ocean. And believe it or not, they’re actually considerably more venomous than land snakes! Jonathan travels to Australia and the Philippines to find these marine reptiles, and learns why they are almost completely harmless to divers.

From the University of Adelaide in Australia:

‘Seeing’ tails help sea snakes avoid predators

February 15, 2019

New research has revealed the fascinating adaptation of some Australian sea snakes that helps protect their vulnerable paddle-shaped tails from predators.

An international study led by the University of Adelaide shows that several species of Australian sea snakes can sense light on their tail skin, prompting them to withdraw their tails under shelter. The study has also produced new insights into the evolution and genetics of this rare light sense.

The researchers found that olive sea snakes (Aipysurus laevis) and other Aipysurus species move their tail away from light. They believe this is an adaptation to keep the tail hidden from sharks and other predators.

“Sea snakes live their entire lives at sea, swimming with paddle-shaped tails and resting at times during the day under coral or rocky overhangs,” says study lead author Jenna Crowe-Riddell, PhD candidate in the University of Adelaide’s School of Biological Sciences. “Because sea snakes have long bodies, the tail-paddle is a large distance from the head, so benefits from having a light-sense ability of its own.

“The olive sea snake was the only reptile, out of more than 10,000 reptile species, that was known to respond to light on the skin in this way.”

The researchers tested for light-sensitive tails in eight species of sea snakes, but found that only three species had the light-sense ability. They concluded the unique ability probably evolved in the ancestor of just six closely related Australian species.

“There are more than 60 species of sea snake so that’s less than 10% of all sea snakes,” says Ms Crowe-Riddell. “We don’t know why this rare sense has evolved in just a few Aipysurus species.”

The researchers used RNA sequencing to see what genes are active in the skin of sea snakes. They discovered a gene for a light-sensitive protein called melanopsin, and several genes that are involved in converting light into information in the nervous system.

“Melanopsin is used in a range of genetic pathways that are linked to sensing overall light levels around us. It is even used by some animals, including humans, for regulating sleep cycles and in frogs to change their skin colour as a camouflage,” says Ms Crowe-Riddell.

Lead scientist Dr Kate Sanders, ARC Future Fellow at the University of Adelaide, says: “We’ve confirmed the ability of olive sea snakes to sense light in their tails and found the same ability in two other species. We’ve identified a shortlist of genes that are likely to be involved in detecting light. But further study will be needed to target these genes before we can really understand the genetic pathways involved in this fascinating behaviour.”

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New dinosaur species discovery in Tanzania


Mnyamawamtuka moyowamkia reconstruction by Mark Witton

From Ohio University in the USA:

New dinosaur with heart-shaped tail provides evolutionary clues for African continent

Mnyamawamtuka moyowamkia fossils recovered from East African Rift System

February 13, 2019

A new dinosaur that wears its “heart” on its tail provides new clues to how ecosystems evolved on the African continent during the Cretaceous period according to researchers at Ohio University.

The OHIO team identified and named the new species of dinosaur in an article published this week in PLOS ONE. The new dinosaur, the third now described from southwestern Tanzania by the NSF-funded team, is yet another member of the large, long-necked titanosaur sauropods. The partial skeleton was recovered from Cretaceous-age (~100 million years ago) rocks exposed in a cliff surface in the western branch of the great East African Rift System.

The new dinosaur is named Mnyamawamtuka moyowamkia (Mm-nya-ma-wah-mm-too-ka mm-oh-yo-wa-mm-key-ah), a name derived from Swahili for “animal of the Mtuka (with) a heart-shaped tail” in reference to the name of the riverbed (Mtuka) in which it was discovered and due to the unique shape of its tail bones.

The initial discovery of Mnyamawamtuka took place in 2004, when part of the skeleton was discovered high in a cliff wall overlooking the seasonally dry Mtuka riverbed, with annual excavations continuing through 2008. “Although titanosaurs became one of the most successful dinosaur groups before the infamous mass extinction capping the Age of Dinosaurs, their early evolutionary history remains obscure, and Mnyamawamtuka helps tell those beginnings, especially for their African-side of the story,” said lead author Dr. Eric Gorscak, a recent Ph.D. graduate of Ohio University, current research associate at the Field Museum of Natural History (Chicago) and new assistant professor at the Midwestern University in Downers Grove, just outside of Chicago. “The wealth of information from the skeleton indicates it was distantly related to other known African titanosaurs, except for some interesting similarities with another dinosaur, Malawisaurus, from just across the Tanzania-Malawi border,” noted Dr. Gorscak.

Titanosaurs are best known from Cretaceous-age rocks in South America, but other efforts by the team include new species discovered in Tanzania, Egypt, and other parts of the African continent that reveal a more complex picture of dinosaurian evolution on the planet. “The discovery of dinosaurs like Mnyamawamtuka and others we have recently discovered is like doing a four-dimensional connect the dots,” said Dr. Patrick O’Connor, professor of anatomy at Ohio University and Gorscak’s advisor during his Ph.D. research. “Each new discovery adds a bit more detail to the picture of what ecosystems on continental Africa were like during the Cretaceous, allowing us to assemble a more holistic view of biotic change in the past.”

The excavation process spanned multiple years, and included field teams suspended by ropes and large-scale mechanical excavators to recover one of the more complete specimens from this part of the sauropod dinosaur family tree. “Without the dedication of several field teams, including some whose members donned climbing gear for the early excavations, the skeleton would have eroded away into the river during quite intense wet seasons in this part of the East African Rift System,” added O’Connor.

“This latest discovery is yet another fine example of how Ohio University researchers work the world over in their pursuit of scientific research,” Ohio University President M. Duane Nellis said. “This team has turned out a number of notable discoveries which collectively contribute significantly to our understanding of the natural world.”

Mnyamawamtuka and the other Tanzanian titanosaurs are not the only animals discovered by the research team. Remains of bizarre relatives of early crocodiles, the oldest evidence for “insect farming”, and tantalizing clues about the early evolution of monkeys and apes have been discovered in recent years. Such findings from the East African Rift provide a crucial glimpse into ancient ecosystems of Africa and provide the impetus for future work elsewhere on the continent.

“This new dinosaur gives us important information about African fauna during a time of evolutionary change,” said Judy Skog, a program director in the National Science Foundation’s Division of Earth Sciences, which funded the research. “The discovery offers insights into paleogeography during the Cretaceous. It’s also timely information about an animal with heart-shaped tail bones during this week of Valentine’s Day.”

Recent findings by the research team in the Rukwa Rift Basin include:

· Shingopana songwensis — titanosaurian sauropod dinosaur, Rukwa Rift Basin

· Rukwatitan bisepultus — titanosaurian sauropod dinosaur, Rukwa Rift Basin

· Pakasuchus kapilimai — mammal-like crocodile, Rukwa Rift Basin

· Early evidence for monkey-ape split, Rukwa Rift Basin Project

· Early evidence of insect farming — Fossil Termite Nests, Rukwa Rift Basin

“The Tanzanian story is far from over but we know enough to start asking what paleontological and geological similarities and dissimilarities there are with nearby rock units. Revisiting Malawi is my top priority to address these broader, regional questions,” said Gorscak, who also participates in ongoing projects in Egypt and Kenya. “With Mnyamawamtuka and other discoveries, I’m not sure to view it as writing or reading the next chapters in the paleontological book of Africa. I’m just excited to see where this story is going to take us.”

New Asian turtle species discovered, endangered


This 2014 video says about itself:

Chinese soft-shell turtle (Pelodiscus sinensis) hatching

Several juveniles of the Chinese soft-shell turtle hatching at the same time.

From ScienceDaily:

Newly discovered turtle species is facing extinction

February 13, 2019

Summary: A new species in the family of Softshell Turtles is described from Northern Vietnam and China by a Hungarian-Vietnamese-German team of researchers. The newly discovered reptile has a distinctly blotched shell and is so critically endangered that it is close to extinction.

For decades, it has been assumed that the Chinese Softshell Turtles from East Asia all belonged to one and the same species, Pelodiscus sinensis. Widely distributed all the way from the Russian Far East through the Korean Peninsula to China and Vietnam, the species was said to vary substantially in terms of its looks across localities. However, around the turn of the century, following a series of taxonomic debates, scientists revalidated or discovered a total of three species distinct from the ‘original’.

Recently, a Hungarian-Vietnamese-German team of researchers described a fifth species in the genus. Their discovery is published in the open-access journal ZooKeys.

The new species, which differs both genetically and morphologically from the other four, has well-pronounced dark blotches on the underside of its shell. The markings are also the reason why these turtles are going by the scientific name Pelodiscus variegatus, where “variegatus” translates to “spotted” in Latin.

“This morphological feature, among others, led to the discovery that these animals belong to a hitherto undescribed species,” explains Professor Dr. Uwe Fritz of the Senckenberg Natural History Collections in Dresden.

Unfortunately, the identification of multiple species within what used to be a single one has its potentially ill-fated consequences. While the Chinese Softshell Turtle was once considered widespread and not threatened, each newly discovered species “reduces” the individual population numbers.

“When we look at each species, the distribution range as well as the number of individuals is much smaller than when all were combined. Until now, the newly described Spotted Softshell Turtle was considered part of the Lesser Chinese Softshell Turtle Pelodiscus parviformis, which was discovered by Chinese researchers in 1997. Pelodiscus parviformis was already considered critically endangered. Now that its southern representatives have been assigned to a different species, the Spotted Softshell Turtle, the overall population size of each species is even smaller,” explains Balázs Farkas, the study’s Hungarian lead author.

Because of its restricted range and the levels of exploitation it is subjected to, the conservation status of the new species is proposed to be Critically Endangered, according to the criteria of the IUCN Red List of Threatened Species.

Triassic turtle had bone cancer


This July 2015 video says about itself:

Resembling a broad-bodied, short-snouted lizard, Pappochelys appears to be an ancestor of modern turles.

By Aimee Cunningham, 6:00am, February 11, 2019:

A rare, ancient case of bone cancer has been found in a turtle ancestor

A 240-million-year-old fossil is the oldest known example of this disease in amniotes

A 240-million-year-old case of bone cancer has turned up in a fossil of an extinct ancestor of turtles. Dating to the Triassic Period, the fossil is the oldest known example of this cancer in an amniote, a group that includes mammals, birds and reptiles, researchers report online February 7 in JAMA Oncology.

The fossilized left femur from the shell-less stem-turtle Pappochelys rosinae was recovered in southwestern Germany in 2013. A growth on the leg bone prompted a team of paleontologists and physicians to analyze the fossil with a micro CT scan, an imaging technique that provides a detailed, three-dimensional view inside an object.

“When we saw that this was not a break or an infection, we started looking at other growth-causing diseases,” says Yara Haridy, a paleontologist at the Museum für Naturkunde in Berlin. The verdict? Periosteal osteosarcoma, a malignant bone tumor. “It looks almost exactly like human periosteal osteosarcoma,” Haridy says.

“It is almost obvious that ancient animals would have cancer, but it is so very rare that we find evidence of it,” she says. The discovery of this tumor from the Triassic offers evidence that cancer is “a vulnerability to mutation deeply rooted in our DNA.”

Cancer genes in mucosal melanoma, a rare and poorly understood subtype of melanoma, have been compared in humans, dogs and horses for the first time. Researchers sequenced the genomes of the same cancer across different species to pinpoint key cancer genes. The results give insights into how cancer evolves across the tree of life and could guide the development of new therapies: here.

Sea snakes don’t drink seawater


This 2014 video says about itself:

In this exciting adventure, Jonathan travels to Manuk, a tiny, uninhabited volcanic island several hundred miles from the nearest populated island in Indonesia, on a mission to discover why the waters of this remote place are teeming with thousands of venomous sea snakes!

And if you love sea snakes, check out our adventure with sea snakes in Australia:

From the University of Florida in the USA:

Sea snakes that can’t drink seawater

Zoology researchers solve mystery of how sea snakes quench their thirst

February 8, 2019

Summary: New research shows that pelagic sea snakes quench their thirst by drinking freshwater that collects on the surface of the ocean after heavy rainfall.

Surrounded by salty water, sea snakes sometimes live a thirsty existence. Previously, scientists thought that they were able to drink seawater, but recent research has shown that they need to access freshwater. A new study published in PLOS ONE on Feb. 7 and led by Harvey Lillywhite, professor of biology of the University of Florida, shows that sea snakes living where there is drought relieve their dehydration as soon as the wet season hits, and do so by obtaining freshwater from “lenses” that form on the surface of the ocean during heavy rain — events in which the salinity at the surface decreases enough for the water to be drinkable.

The yellow-bellied sea snake (Hydrophis platurus) is the only reptile in the order Squamata that lives on the open sea. It has one of the largest geographic ranges of any vertebrate species. Given its broad range and seafaring existence, during the dry season (6-7 months at the study site in Costa Rica) it has no access to freshwater. How they survive in regions of drought seems to hinge upon access to freshwater lenses, but little is known about how marine vertebrates react to or consume rainfall. “This study contributes to a fuller understanding of how pelagic sea snakes, and possibly other marine animals, avoid desiccation following seasonal drought at sea,” said Lillywhite.

The researchers captured 99 sea snakes off the coast of Costa Rica (interestingly, the snakes have never been observed in estuaries) and offered them freshwater in a laboratory environment. The team happened to be there just as six months of drought broke and the rainy season began. They found that only 13 percent of snakes captured after the rainfall began accepted the offer, compared to 80 percent of those captured before. The rainfall must have quenched their thirst.

The study continues many years of work by Lillywhite. The present paper was coauthored by Mark Sandfoss, Lillywhite’s current PhD student, Coleman Sheehy, his former student who is now the Collections Manager in Herpetology at the Florida Museum of Natural History, and then-Fulbright visiting scholar Jenna Crowe-Riddell.

“How these animals locate and harvest precipitation is important in view of the recent declines and extinctions of some species of sea snakes,” said Lillywhite. The question remains: How will climate change and its effects on precipitation impact the sea snakes?

New dinosaur species discovery in Mongolia


Postcranial elements of the holotype specimen (MPC-D 102/111) of Gobiraptor minutus gen. et sp. nov. (A) Skeletal reconstruction in left lateral view (missing and damaged portions of the bones in gray). Credit: Sungjin Lee et al. A new baby oviraptorid dinosaur (Dinosauria: Theropoda) from the Upper Cretaceous Nemegt Formation of Mongolia

From PLOS:

Fossils of new oviraptorosaur species discovered in Mongolia

Incomplete skeleton of Gobiraptor minutus was likely that of a juvenile

February 6, 2019

A new oviraptorosaur species from the Late Cretaceous was discovered in Mongolia, according to a study published in February 6, 2019 in the open-access journal PLOS ONE by Yuong-Nam Lee from Seoul National University, South Korea, and colleagues.

Oviraptorosaurs were a diverse group of feathered, bird-like dinosaurs from the Cretaceous of Asia and North America. Despite the abundance of nearly complete oviraptorosaur skeletons discovered in southern China and Mongolia, the diet and feeding strategies of these toothless dinosaurs are still unclear. In this study, Lee and colleagues described an incomplete skeleton of an oviraptorosaur found in the Nemegt Formation of the Gobi desert of Mongolia.

The new species, named Gobiraptor minutus, can be distinguished from other oviraptorosaurs in having unusual thickened jaws. This unique morphology suggests that Gobiraptor used a crushing feeding strategy, supporting previous hypotheses that oviraptorosaurs probably fed on hard food items such as eggs, seeds or hard-shell mollusks. Histological analyses of the femur revealed that the specimen likely belonged to a very young individual.

The finding of a new oviraptorosaur species in the Nemegt Formation, which consists mostly of river and lake deposits, confirms that these dinosaurs were extremely well adapted to wet environments. The authors propose that different dietary strategies may explain the wide taxonomic diversity and evolutionary success of this group in the region.

The authors add: “A new oviraptorid dinosaur Gobiraptor minutus gen. et sp. nov. from the Upper Cretaceous Nemegt Formation is described here based on a single holotype specimen that includes incomplete cranial and postcranial elements. The unique morphology of the mandible and the accordingly inferred specialized diet of Gobiraptor also indicate that different dietary strategies may be one of important factors linked with the remarkably high diversity of oviraptorids in the Nemegt Basin.”

How snakes lost their limbs


This February 2018 video says about itself:

90 million years ago, an ancient snake known as Najash had…legs. It is by no means the only snake to have limbs either. But what’s even stranger: we’re not at all sure where it came from.

From the Fundação de Amparo à Pesquisa do Estado de São Paulo in Brazil:

Research explains how snakes lost their limbs

The study is part of an effort to understand how changes in the genome lead to changes in phenotypes

February 6, 2019

Snakes and lizards are reptiles that belong to the order Squamata. They share several traits but differ in one obvious respect: snakes do not have limbs. The two suborders diverged more than 100 million years ago.

Identification of the genetic factors involved in this loss of limbs is a focus of the article “Phenotype loss is associated with widespread divergence of the gene regulatory landscape in evolution” published by Juliana Gusson Roscito and collaborators in Nature Communications.

Another equally interesting focus of the article is eye degeneration in certain subterranean mammals.

“We investigated these two cases in order to understand a much more general process, which is how genome changes during evolution lead to phenotype changes,” Roscito told.

Currently working as a researcher at the Max Planck Institute for Molecular Cell Biology and Genetics in Dresden, Germany, Roscito has been a postdoctoral fellow in Brazil and a research intern abroad with São Paulo Research Foundation — FAPESP’s support. Her postdoctoral scholarship was linked to the Thematic Project “Comparative phylogeography, phylogeny, paleoclimate modeling and taxonomy of neotropical reptiles and amphibians,” for which Miguel Trefaut Urbano Rodrigues is the principal investigator under the aegis of the FAPESP Research Program on Biodiversity Characterization, Conservation, Restoration and Sustainable Use (BIOTA-FAPESP).

Rodrigues is a Full Professor at the University of São Paulo’s Bioscience Institute (IB-USP) in Brazil and supervised Roscito’s postdoctoral research. He is also a coauthor of the recently published article.

“The research consisted of an investigation of the genomes of several species of vertebrates, including the identification of genomic regions that changed only in snakes or subterranean mammals, while remaining unchanged in other species that have not lost their limbs or have normal eyes,” Roscito said.

“In mammals with degenerated visual systems, we know several genes have been lost, such as those associated with the eye’s crystalline lens and with the retina’s photoreceptor cells. These genes underwent mutations during the evolutionary process. Eventually, they completely lost their functionality, meaning the capacity to encode proteins. But that’s not what happened to snakes, which haven’t lost the genes associated with limb formation. To be more precise, the study that sequenced the genome of a snake did detect the loss of one gene, but only one. Therefore, the approach we chose in our research consisted of investigating not the genes but the elements that regulate gene expression.”

Gene expression depends on regulatory elements for the information the gene contains to be transcribed into RNA (ribonucleic acid) and later translated into protein. This process is regulated by cis-regulatory elements (CREs), which are sequences of nucleotides in DNA (deoxyribonucleic acid) located near the genes they regulate. CREs control the spatiotemporal and quantitative patterns of gene expression.

“A regulatory element can activate or inhibit the expression of a gene in a certain part of the organism, such as the limbs, for example, while a different regulatory element can activate or inhibit the expression of the same gene in a different part, such as the head. If the gene is lost, it ceases to be expressed in both places and can often have a negative effect on the organism’s formation.

However, if only one of the regulatory elements is lost, expression may disappear in one part while being conserved in the other,” Roscito explained.

Tegu lizard

From a computational standpoint, CREs are not as easy to identify as genes. Genes have a characteristic syntax, with base pairs that show where the genes begin and end. This is not the case for CREs, so they have to be identified indirectly. This identification is normally based on the conservation of DNA sequences among many different species.

“To detect the divergence of specific sequences in snakes, it’s necessary to compare the genomes of snakes with the genomes of various reptiles and other vertebrates that have fully developed limbs. Genome sequences for reptiles with well-developed limbs are scarce, so we sequenced and assembled the genome of the fully limbed tegu lizard, Salvator merianae. This is the first species of the teiid lineage ever sequenced,” the authors said.

“Using the tegu genome as a reference, we created an alignment of the genomes of several species, including two snakes (boa and python), three other limbed reptiles (green anole lizard, dragon lizard and gecko), three birds, an alligator, three turtles, 14 mammals, a frog, and a coelacanth. This alignment of 29 genomes was used as the basis for all further analyses.”

The researchers identified more than 5,000 DNA regions that are considered candidate regulatory elements in several species. They then searched the large database using ingenious technical procedures that are described in detail in the article and obtained a set of CREs the mutation of which may have led to the disappearance of limbs in the ancestors of snakes.

“There are several studies concerning a well-known regulatory element that regulates a gene that, when modified, causes various defects in limbs. Snakes have mutations in this CRE. In a study published in 2016, the mouse CRE was replaced with the snake version, resulting in practically limbless descendants. This was a functional demonstration of a mechanism that may have led to limb loss in snakes. However, this CRE is only one of the regulatory elements for one of several genes that control limb formation,” Roscito said.

“Our study extended the set of CREs. We showed that several other regulatory elements responsible for regulating many genes have mutated in snakes. The signature is far more comprehensive. An entire signaling cascade is affected.”