Tuatara reptiles’ genome, similar to mammals

This January 2020 video says about itself:

Today, Department of Conservation rangers Lee and Joyce are in search of a rare animal found only on an island in New Zealand. Follow them on their quest to find and breed two Tuataras, an ancient reptile that predates the dinosaurs.

From Northern Arizona University in the USA:

Dinosaur relative’s genome linked to mammals: Curious genome of ancient reptile

August 5, 2020

A lizard-like creature whose ancestors once roamed the Earth with dinosaurs and today is known to live for longer than 100 years may hold clues to a host of questions about the past and the future.

In a study published Aug. 5 in Nature, an interdisciplinary, international team of researchers, in partnership with Maori tribe Ngatiwai, sequenced, assembled and analyzed the complete genome of the Sphenodon punctatus, or the tuatara, a rare reptile whose ancestors once roamed the earth with dinosaurs. It hasn’t changed much in the 150 million to 250 million years since then.

“We found that the tuatara genome has accumulated far fewer DNA substitutions over time than other reptiles, and the molecular clock for tuataras ticked at a much slower speed than squamates, although faster than turtles and crocodiles, which are the real molecular slowpokes,” said co-author Marc Tollis, an assistant professor in the School of Informatics, Computing, and Cyber Systems at Northern Arizona University. “This means in terms of the rate of molecular evolution, tuataras are kind of the Toyota Corolla — nothing special but very reliable and persistently ticking away over hundreds of millions of years.”

Tuatara have been out on their own for a staggering amount of time, with prior estimates ranging from 150-250 million years, and with no close relatives the position of tuatara on tree of life has long been contentious. Some argue tuatara are more closely related to birds, crocodiles and turtles, while others say they stem from a common ancestor shared with lizards and snakes. This new research places tuatara firmly in the branch shared with lizards and snakes, but they appear to have split off and been on their own for about 250 million years — a massive length of time considering primates originated about 65 million years ago, and hominids, from which humans descend, originated approximately six million years ago.

“Proving the phylogenetic position of tuatara in a robust way is exciting, but we see the biggest discovery in this research as uncovering the genetic code and beginning to explore aspects of the biology that makes this species so unique, while also developing new information that will help us better conserve this taonga or special treasure,” said lead author Neil Gemmell, a professor at the University of Otago.

One area of particular interest is to understand how tuataras, which can live to be more than 100 years old, achieve such longevity. Examining some of the genes implicated in protecting the body from the ravages of age found that tuatara have more of these genes than any other vertebrate species thus far examined, including humans. This could offer clues into how to increase humans’ resistance to the ailments that kill humans.

But the genome, and the tuatara itself, has so many other unique features all on its own. For one, scientists have found tuatara fossils dating back 150 million years, and they look exactly the same as the animals today. The fossil story dates the tuatara lineage to the Triassic Period, when dinosaurs were just starting to roam the Earth.

“The tuatara genome is really a time machine that allows us to understand what the genetic conditions were for animals that were vying for world supremacy hundreds of millions of years ago,” he said. “A genome sequence from an animal this ancient and divergent could give us a better idea about what the ancestral amniote genome might have looked like.”

While modern birds are the descendants of dinosaurs, they are less suitable for this type of research because avian genomes have lost a significant amount of DNA since diverging from their dinosaur ancestors.

But the tuataras, which used to be spread throughout the world, have other unusual features. Particularly relevant to this research is the size of its genome; the genome of this little lizard has 5 billion bases of DNA, making it 67 percent larger than a human genome. Additionally, tuataras have temperature-based sex determination, which means the ratio of males to females in a clutch of eggs depends on the temperatures at which they are incubated. They also have a pronounced “third eye” — a light sensory organ that sticks through the top of their skulls. Mammals’ skulls have completely covered the third eye, though they still contain the pineal gland underneath, which helps maintain circadian rhythms.

The tuatara also is unique in that it is sacred to the Maori people. This research, for all the scientific knowledge that came from it, was groundbreaking for its collaboration with the Indigenous New Zealanders. The purpose was to ensure the research aligned with and respected the importance of the tuatara in their culture, which has never been done before in genomic research.

“Tuatara are a taonga, and it’s pleasing to see the results of this study have now been published,” Ngatiwai Trust Board resource management unit manager Alyx Pivac said. “Our hope is that this is yet another piece of information that will help us understand tuatara and aid in the conservation of this special species. We want to extend a big mihi to all of those who have been involved in this important piece of work.”

With the genome now sequenced, the international science community has a blueprint through which to examine the many unique features of tuatara biology, which will aid human understanding of the evolution of the amniotes, a group that includes birds, reptiles and mammals.

Dinosaurs could get cancer

This 4 August 2020 video, in Indonesian, is about the recent discovery that a Centrosaurus dinosaur had bone cancer.

Translated from Dutch NOS radio today:

Canadian scientists have for the first time found evidence that dinosaurs could also develop bone cancer.

Paleontologists discovered this when they re-examined malformations on the fossil of a Centrosaurus – a horned, herbivorous dinosaur that lived in the Cretaceous period more than 70 million years ago.

The fossil was excavated in the Canadian province of Alberta in 1989 and was notable for a fibula defect, which was then assessed by scientists as a healed fracture. New research with detailed CT scans found it likely to be an aggressive form of bone cancer.

The tumor was the size of an apple, the scientists said in an article in the scientific journal Lancet Oncology.

Triassic dinosaurs family tree, new research

This 2016 video says about itself:


Dinosaurs are a diverse group of animals of the clade Dinosauria. They first appeared during the Triassic period, 231.4 million years ago, and were the dominant terrestrial vertebrates for 135 million years, from the start of the Jurassic (about 200 million years ago) until the end of the Cretaceous (66 million years ago), when the Cretaceous–Paleogene extinction event led to the extinction of most dinosaur groups at the end of the Mesozoic Era.

The fossil record indicates that birds are modern feathered dinosaurs, having evolved from theropod ancestors during the Jurassic Period. Birds were the only dinosaurs to survive the extinction event that occurred 66 million years ago.

From the Massachusetts Institute of Technology in the USA:

Study sheds light on the evolution of the earliest dinosaurs

Geological evidence suggests the known dinosaur groups diverged early on, supporting the traditional dinosaur family tree

July 29, 2020

Summary: Geological evidence suggests the known dinosaur groups diverged early on, supporting the traditional dinosaur family tree.

The classic dinosaur family tree has two subdivisions of early dinosaurs at its base: the Ornithischians, or bird-hipped dinosaurs, which include the later Triceratops and Stegosaurus; and the Saurischians, or lizard-hipped dinosaurs, such as Brontosaurus and Tyrannosaurus.

In 2017, however, this classical view of dinosaur evolution was thrown into question with evidence that perhaps the lizard-hipped dinosaurs evolved first — a finding that dramatically rearranged the first major branches of the dinosaur family tree.

Now an MIT geochronologist, along with paleontologists from Argentina and Brazil, has found evidence to support the classical view of dinosaur evolution. The team’s findings are published today in the journal Scientific Reports.

The team reanalyzed fossils of Pisanosaurus, a small bipedal dinosaur that is thought to be the earliest preserved Ornithiscian in the fossil record. The researchers determined that the bird-hipped herbivore dates back to 229 million years ago, which is also around the time that the earliest lizard-hipped Saurischians are thought to have appeared.

The new timing suggests that Ornithiscians and Saurischians first appeared and diverged from a common ancestor at roughly the same time, giving support to the classical view of dinosaur evolution.

The researchers also dated rocks from the Ischigualasto Formation, a layered sedimentary rock unit in Argentina that is known for having preserved an abundance of fossils of the very earliest dinosaurs. Based on these fossils and others across South America, scientists believe that dinosaurs first appeared in the southern continent, which at the time was fused together with the supercontinent of Pangaea. The early dinosaurs are then thought to have diverged and fanned out across the world.

However, in the new study, the researchers determined that the period over which the Ischigualasto Formation was deposited overlaps with the timing of another important geological deposit in North America, known as the Chinle Formation.

The middle layers of the Chinle Formation in the southwestern U.S. contain fossils of various fauna, including dinosaurs that appear to be more evolved than the earliest dinosaurs. The bottom layers of this formation, however, lack animal fossil evidence of any kind, let alone early dinosaurs. This suggests that conditions within this geological window prevented the preservation of any form of life, including early dinosaurs, if they walked this particular region of the world.

“If the Chinle and Ischigualasto formations overlap in time, then early dinosaurs may not have first evolved in South America, but may have also been roaming North America around the same time,” says Jahandar Ramezani, a research scientist in MIT’s Department of Earth, Atmospheric, and Planetary Sciences, who co-authored the study. “Those northern cousins just may not have been preserved.”

The other researchers on the study are first author Julia Desojo from the National University of La Plata Museum, and a team of paleontologists from institutions across Argentina and Brazil.

“Following footsteps”

The earliest dinosaur fossils found in the Ischigualasto Formation are concentrated within what is now a protected provincial park known as “Valley of the Moon” in the San Juan Province. The geological formation also extends beyond the park, albeit with fewer fossils of early dinosaurs. Ramezani and his colleagues instead looked to study one of the accessible outcrops of the same rocks, outside of the park.

They focused on Hoyada del Cerro Las Lajas, a less-studied outcrop of the Ischigualasto Formation, in La Rioja Province, which another team of paleontologists explored in the 1960s.

“Our group got our hands on some of the field notes and excavated fossils from those early paleontologists, and thought we should follow their footsteps to see what we could learn,” Desojo says.

Over four expeditions between 2013 to 2019, the team collected fossils and rocks from various layers of the Las Lajas outcrop, including more than 100 new fossil specimens, though none of these fossils were of dinosaurs. Nevertheless, they analyzed the fossils and found they were comparable, in both species and relative age, to nondinosaur fossils found in the park region of the same Ischigualasto Formation. They also found out that the Ischigualasto Formation in Las Lajas was significantly thicker and much more complete than the outcrops in the park. This gave them confidence that the geological layers in both locations were deposited during the same critical time interval.

Ramezani then analyzed samples of volcanic ash collected from several layers of the Las Lajas outcrops. Volcanic ash contains zircon, a mineral that he separated from the rest of the sediment, and measured for isotopes of uranium and lead, the ratios of which yield the mineral’s age.

With this high-precision technique, Ramezani dated samples from the top and bottom of the outcrop, and found that the sedimentary layers, and any fossils preserved within them, were deposited between 230 million and 221 million years ago. Since the team determined that the layered rocks in Las Lajas and the park match in both species and relative timing, they could also now determine the exact age of the park’s more fossil-rich outcrops.

Moreover, this window overlaps significantly with the time interval over which sediments were deposited, thousands of kilometers northward, in the Chinle Formation.

“For many years, people thought Chinle and Ischigualasto formations didn’t overlap, and based on that assumption, they developed a model of diachronous evolution, meaning the earliest dinosaurs appeared in South America first, then spread out to other parts of the world including North America,” Ramezani says. “We’ve now studied both formations extensively, and shown that diachronous evolution isn’t really based on sound geology.”

A family tree, preserved

Decades before Ramezani and his colleagues set out for Las Lajas, other paleontologists had explored the region and unearthed numerous fossils, including remains of Pisanosaurus mertii, a small, light-framed, ground-dwelling herbivore. The fossils are now preserved in an Argentinian museum, and scientists have gone back and forth on whether it is a true dinosaur belonging to the Ornithiscian group, or a ” basal dinosauromorph” — a kind of pre-dinosaur, with features that are almost, but not quite fully, dinosaurian.

“The dinosaurs we see in the Jurassic and Cretaceous are highly evolved, and ones we can nicely identify, but in the late Triassic, they all looked very much alike, so it’s very hard to distinguish them from each other, and from basal dinosauromorphs,” Ramezani explains.

His collaborator Max Langer from the University of São Paulo in Brazil painstakingly reanalyzed the museum-preserved fossil of Pisanosaurus, and concluded, based on certain key anatomical features, that it is indeed a dinosaur — and what’s more, that it is the earliest preserved Ornithiscian specimen. Based on Ramezani’s dating of the outcrop and the interpretation of Pisanosaurus, the researchers concluded that the earliest bird-hipped dinosaurs appeared around 229 million years ago — around the same time as their lizard-hipped counterparts.

“We can now say the earliest Ornithiscians first showed up in the fossil record roughly around the same time as the Saurischians, so we shouldn’t throw away the conventional family tree,” Ramezani says. “There are all these debates about where dinosaurs appeared, how they diversified, what the family tree looked like. A lot of those questions are tied to geochronology, so we need really good, robust age constraints to help answer these questions.”

This research was mainly funded by the National Council for Scientific and Technical Research (Argentina) and the São Paulo State Research Support Foundation (Brazil). Geochronologic research at the MIT Isotope Lab has been supported in part by the U.S. National Science Foundation.

Rattlesnakes can stand a bit of cold

This 2017 video from thed USA is called Explore The Western Diamondback Rattlesnake! | Real Wild.

From the University of California – Riverside in the USA:

Hot or cold, venomous vipers still quick to strike

Cold weather makes rattlesnakes more vulnerable — but not much

July 23, 2020

Most reptiles move slower when temperatures drop, but venomous rattlesnakes appear to be an exception. The cold affects them, but not as much as scientists expected.

“Many reptiles and other animals that rely on external sources of heat have muscles that don’t contract as well when temperature drops. We wanted to know if that was the case with rattlesnakes,” explained UC Riverside biologist Tim Higham.

To answer their question, Higham and a team from San Diego State University examined the speed at which rattlers struck out at perceived threats in temperature-controlled containers. The team’s work is detailed in a new paper published this week in the Journal of Experimental Biology.

The team investigated how quickly the snakes struck out to defend themselves when faced with predators, as this speed can make the difference between life and death in nature.

“Although humans often fear snakes, it is important to realize that snakes are vulnerable to predation by animals such as birds, mammals, and other snakes,” Higham said. “Defensive strikes are important for protecting them against predation.”

When placed in the experimental containers, the research team found that rattlers continued to strike quickly at a balloon filled with warm water that played the role of an intruder.

“By far, the hardest part of the study was working with snakes in the 35 C treatment,” said San Diego State University doctoral student Malachi Whitford, first author of the new study. “The snakes were extremely fast, making them very difficult to corral.”

The strike speed was affected when the temperature dropped, but not as much as the team thought it would be.

“We expected their strike to be about half as fast for every 10-degree drop in temperature, but they’re still able to uncoil and strike fairly rapidly, even at our lowest test temperatures,” said SDSU ecologist and research team member Rulon Clark.

At most, the snakes were about 25 percent slower at the lowest temperature. The finding means that pit vipers, the type of rattlesnake studied, are slightly more vulnerable to real or perceived threats in colder temperatures but not by a lot.

This might help explain how rattlesnakes can thrive even in cooler climates like southern Canada. It also suggests that the snakes are using a mechanism other than just muscles in order to strike, as muscle movement becomes more difficult in the cold.

Kangaroos use tendons like elastic bands to bounce and hop without using much energy, the way that humans use a bow and arrow. The findings suggest that snakes may also be storing elastic energy somehow.

“Striking in any way is important to do quickly,” Higham said. “As global temperatures increase, it’s possible that snakes will become even more effective predators.”

Triassic era catastrophes and wildlife

This 18 June 2020 video from the USA says about itself:

Big Amphibians of the Chinle Formation!

Dinosaur Journey Re-Opens today! And to celebrate we wanted to share a video of Dr. Julia McHugh talking amphibians. Ever noticed the large red rock base of Independence Monument?! Well, that’s the Triassic age rock these amazing creatures were discovered. WATCH now to learn more!

From the University of Texas at Austin in the USA:

Arizona rock core sheds light on Triassic dark ages

July 20, 2020

A rock core from Petrified Forest National Park, Arizona, has given scientists a powerful new tool to understand how catastrophic events shaped Earth’s ecosystems before the rise of the dinosaurs.

The quarter-mile core is from an important part of the Triassic Period when life on Earth endured a series of cataclysmic events: Our planet was struck at least three times by mountain-sized asteroids, chains of volcanoes erupted to choke the sky with greenhouse gases, and tectonic movement tore apart Earth’s single supercontinent, Pangea.

Among the chaos, many plants and animals, including some of the long-snouted and armored reptiles that ruled Pangea throughout the Triassic, vanished in a possible shake-up of life on Earth that scientists have yet to explain.

The study, published July 20 in GSA Bulletin, offers scientists a foundation to explain the changes in the fossil record and determine how these events may have shaped life on Earth.

By determining the age of the rock core, researchers were able to piece together a continuous, unbroken stretch of Earth’s history from 225 million to 209 million years ago. The timeline offers insight into what has been a geologic dark age and will help scientists investigate abrupt environmental changes from the peak of the Late Triassic and how they affected the plants and animals of the time.

“The core lets us wind the clock back 225 million years when Petrified Forest National Park was a tropical hothouse populated by crocodile-like reptiles and turkey-size early dinosaurs,” said Cornelia Rasmussen, a postdoctoral researcher at the University of Texas Institute for Geophysics (UTIG), who led the analysis that determined the age of the core.

“We can now begin to interpret changes in the fossil record, such as whether changes in the plant and animal world at the time were caused by an asteroid impact or rather by slow geographic changes of the supercontinent drifting apart,” she said.

Petrified Forest National Park’s paleontologist Adam Marsh said that despite a rich collection of fossils from the period in North America, until now there was little information on the Late Triassic’s timeline because most of what scientists knew came from studying outcrops of exposed rock pushed to the surface by tectonic movements.

“Outcrops are like broken pieces of a puzzle,” said Marsh, who earned his Ph.D. from The University of Texas at Austin’s Jackson School of Geosciences. “It is incredibly difficult to piece together a continuous timeline from their exposed and weathered faces.”

Marsh was not an author of the study but is part of the larger scientific coring project. UTIG is a unit of the Jackson School.

The Petrified Forest National Park core overcomes the broken puzzle problem by recovering every layer in the order it was deposited. Like tree rings, scientists can then match those layers with the fossil and climate record.

To find the age of each layer, the researchers searched the rock core for tiny crystals of the mineral zircon, which are spewed into the sky during volcanic eruptions. Zircons are a date stamp for the sediments with which they are buried. Researchers then compared the age of the crystals with traces of ancient magnetism stored in the rocks to help develop a precise geologic timeline.

Geoscience is rarely so simple, however, and according to Rasmussen, the analysis of the core gave them two slightly different stories. One shows evidence that a shake-up in the species might not be connected to any single catastrophic event and could simply be part of the ordinary course of gradual evolution. The other shows a possible correlation between the change in the fossil record and a powerful asteroid impact, which left behind a crater in Canada over 62 miles wide.

For Marsh, the different findings are just part of the process to reach the truth.

“The two age models are not problematic and will help guide future studies,” he said.

The research is the latest outcome of the Colorado Plateau Coring Project. The research and the coring project were funded by the National Science Foundation and International Continental Drilling Program.

How sea turtles migrate, new research

This 20212 video says about itself:

An educational video by SEE Turtles about sea turtle migrations including leatherbacks and loggerheads. Learn how these amazing animals swim thousands of miles to find food and nesting beaches.

From ScienceDaily:

Sea turtles’ impressive navigation feats rely on surprisingly crude ‘map’

July 16, 2020

Since the time of Charles Darwin, scientists have marveled at sea turtles’ impressive ability to make their way — often over thousands of kilometers — through the open ocean and back to the very places where they themselves hatched years before. Now, researchers reporting in the journal Current Biology on July 16 have evidence that the turtles pull off these impressive feats of navigation with only a crude map to guide them on their way, sometimes going far off course before correcting their direction.

“By satellite tracking turtles travelling to small, isolated oceanic islands, we show that turtles do not arrive at their targets with pinpoint accuracy,” says Graeme Hays of Australia’s Deakin University. “While their navigation is not perfect, we showed that turtles can make course corrections in the open ocean when they are heading off-route. These findings support the suggestion, from previous laboratory work, that turtles use a crude true navigation system in the open ocean, possibly using the earth’s geomagnetic field.”

Despite much study of sea turtle navigation, many details were lacking. Hays’ team realized that was in part because most sea turtles return to spots along the mainland coast, which are also the easiest places to find.

For the new study, his team had attached satellite tags to nesting green turtles (Chelonia mydas) out of an interest in learning about the extent of the turtles’ movements and to identify key areas for conservation. In the process, they realized that, by serendipity, many of the tracked turtles travelled to foraging sites on isolated islands or submerged banks. It allowed them to explore in more detail how turtles make their way to such small and harder-to-find islands.

In total, the researchers recorded the tracks of 33 green sea turtles migrating across the open ocean from their nesting beaches on the island of Diego Garcia (Indian Ocean) to their foraging grounds across the western Indian Ocean, many of which were isolated island targets. Using individual-based models that incorporated ocean currents, they then compared actual migration tracks against candidate navigational models to show that 28 of the 33 turtles didn’t re-orient themselves daily or at fine-scales.

As a result, the turtles sometimes travelled well out of their way — several hundred kilometers off the direct routes to their goal — before correcting their direction, often in the open ocean. Frequently, they report, turtles did not reach their small island destinations with pinpoint accuracy. Instead, they often overshot and or spent time searching for the target in the final stages of migration.

“We were surprised that turtles had such difficulties in finding their way to small targets,” Hays says. “Often they swam well off course and sometimes they spent many weeks searching for isolated islands.

“We were also surprised at the distance that some turtles migrated. Six tracked turtles travelled more than 4,000 kilometers to the east African coast, from Mozambique in the south, to as far north as Somalia. So, these turtles complete round-trip migrations of more than 8,000 kilometers to and from their nesting beaches in the Chagos Archipelago.”

The findings lend support to the notion that migrating sea turtles use a true navigation system in the open ocean. They also provide some of the best evidence to date that migrating sea turtles have an ability to re-orient themselves in deep waters in the open ocean, the researchers say. This implies that they have and rely on a map sense. But the results also show that their map lacks fine details, allowing them to operate only at a crude level.

As a result of this imperfect navigation system, the turtles reach their destination only imperfectly. In the process, the turtles spend extra energy and time searching for small islands.

The findings also have implications for the turtles’ conservation, Hays says. Turtles travel broadly across the open ocean once nesting season has finished. As a result, he says, “conservation measures need to apply across these spatial scales and across many countries.”

The researchers say that they hope the next generation of tag technology will allow them to directly measure the compass heading of migrating turtles as well as their location. “Then we can directly assess how ocean currents carry turtles off-course and gain further insight into the mechanisms that allow turtles to complete such prodigious feats of navigation,” Hays says.

American crocodiles, new research

This 21 September 2019 video from the USA says about itself:

Dave and Jeremy get you up close to the American Crocodile in the Florida Everglades. It is the only other crocodilian native to the U.S. and the southern tip of Florida is the only place to find them here. This episode is sure to have a lot of bite!

From the University of Bristol in Germany:

Genetic differences between global American Crocodile populations identified in DNA analysis

July 13, 2020

A genetic analysis of the American crocodile (Crocodylus acutus) has re-established our understanding of its population structure, aiding its conservation. The collaborative study spanning seven countries and led by the Wildlife Conservation Society and University of Bristol researchers is published in PLOS ONE.

The American crocodile is widespread across the American continent (from South Florida to Venezuela, across the Greater Antilles, and from Mexico to Ecuador). Successful due to its ability to thrive within brackish and saltwater environments. Efforts to conserve the crocodile species have existed since 1975 when their status was set to vulnerable on the IUCN (International Union for Conservation of Nature) red list. However, although conservation efforts have been put in place, the American crocodile faces further threats including habitat degradation due to coastal development.

Replenishing these populations requires understanding of population structures through genetic analysis, which can elaborate on the evolution of the species’ distribution. Gaining more understanding on how a species has come to be distributed so widely and how populations can differentiate genetically, can inform regions how best to manage their populations.

The study reflected a regional collaborative effort, where DNA sampling occurred across seven countries including Venezuela, Jamaica and Cuba. There has been ongoing discussion on how these regional populations of C.acutus are similar. However, the study’s results found that populations in Northern, Central and Southern America’s and Great Antilles differed genetically. There were similarities found between Costa Rica and Jamaican populations. In Venezuela, they identified three new haplotypes, which are closely related genes that help scientists identify an origin of distribution.

Researchers believe that the mating with different species could have contributed to this distribution, also known as hybridisation. Crocodiles hybridise easily, contributing to their ability to survive since the prehistoric era. Additionally, in Florida genetic analysis showed there had been a case of unintentional translocation, where the species had been moved from a different location over time. This had been flagged by previous research, where crocodiles with haplotypes from Central and South America had been transported to Florida, most likely for the pet trade, and later escaped or released into the wild by owners.

By identifying these differences between regional populations of C. acutus, conservation efforts can establish population clusters which consider the populations as independent management units that may have different needs and focuses.

Natalia Rossi, Country Manager of the Cuba Program at the Wildlife Conservation Society and the study’s co-author explains some of the challenges around taking samples from large crocodiles: “Our study involved several research teams across multiple sites and countries and often in difficult field conditions. For four years between May to July the team would record, mark and sample crocodile hatchings, and juvenile and adult crocodiles in Cuba‘s Birama Swamp, one of the study sites. It was not unusual for us to have to spend hours in the mangrove lakes waiting for one to appear, and when a crocodile was spotted the whole team would have to enter the water to help net it. While both exciting and rewarding work, it is also dangerous as the crocodiles are powerful and it involves lots of team co-ordination and trust to secure the crocodile to enable us to take samples.”

The study was ambitious and could not have been achieved without its global collaboration and efforts from its long list of authors. In particular, the late John Thorbjarnarson and Rafael Crespo, who dedicated their lives to this research.

Venomous snakes in Croatia, video

This 9 July 2020 video says about itself:

Croatia has a high diversity of snakes by European standards. Some species are venomous, like the Nose-horned viper (Vipera ammodytes) and Eastern Montpellier snake (Malpolon insignitus).

Living Zoology went for a short trip to Croatia and found both. Nose-horned viper is a front-fanged snake and it was the first venomous snake we found together. That’s why it is in our logo. Malpolon is a rear-fanged species and we found it for the first time during this trip.

Young dinosaur jawbone discovery in Alaska

This January 2019 video from the Milwaukee Public Museum in the USA says about itself:

MPM Untold – The Dromaeosaur

T.rex has a new friend in the Hell Creek exhibit. Want to meet him? Watch MPM Untold and find out what’s been updated!

From PLOS:

Fossil jawbone from Alaska is a rare case of a juvenile Arctic dromaeosaurid dinosaur

This fossil is a clue to the history of how dinosaurs dispersed between continents, showing some dinosaurs likely nested in the far north

July 8, 2020

A small piece of fossil jawbone from Alaska represents a rare example of juvenile dromaeosaurid dinosaur remains from the Arctic, according to a study published July 8, 2020 in the open-access journal PLOS ONE by Alfio Alessandro Chiarenza of the Imperial College London, UK, and co-authors Anthony R. Fiorillo, Ronald S. Tykoski, Paul J. McCarthy, Peter P. Flaig, and Dori L. Contreras.

Dromaeosaurids are a group of predatory dinosaurs closely related to birds, whose members include well-known species such as Deinonychus and Velociraptor. These dinosaurs lived all over the world, but their bones are often small and delicate and rarely preserve well in the fossil record, complicating efforts to understand the paths they took as they dispersed between continents.

The Prince Creek Formation of northern Alaska preserves the largest collection of polar dinosaur fossils in the world, dating to about 70 million years ago, but the only dromaeosaurid remains found so far have been isolated teeth. The jaw fossil described in this study is a mere 14mm long and preserves only the tip of the lower jaw, but it is the first known non-dental dromaeosaurid fossil from the Arctic. Statistical analysis indicates this bone belongs to a close relative of the North American Saurornitholestes.

North American dromaeosaurids are thought to trace their origins to Asia, and Alaska would have been a key region for the dispersal of their ancestors. This new fossil is a tantalizing clue toward understanding what kinds of dromaeosaurs inhabited this crucial region. Furthermore, the early developmental stage of the bone suggests this individual was still young and was likely born nearby; in contrast to previous suggestions that this part of Alaska was exclusively a migratory pathway for many dinosaurs, this is strong evidence that some dinosaurs were nesting here. The authors suggest that future findings may allow a more complete understanding of these mysterious Arctic dromaeosaurids.

Chiarenza summarizes: “There are places where dinosaur fossils are so common that a scrap of bone, in most cases, cannot really add anything scientifically informative anymore: this is not the case with this Alaskan specimen. Even with such an incomplete jaw fragment, our team was not only able to work out the evolutionary relationships of this dinosaur, but also to picture something more on the biology of these animals, ultimately gaining more information on this Ancient Arctic ecosystem.” Fiorillo adds: “Years ago when dinosaurs were first found in the far north, the idea challenged what we think we know about dinosaurs. For some time afterwards, there was a great debate as to whether or not those Arctic dinosaurs migrated or lived in the north year-round. All of those arguments were somewhat speculative in nature. This study of a predatory dinosaur jaw from a baby provides the first physical proof that at least some dinosaurs not only lived in the far north, but they thrived there. One might even say, our study shows that the ancient north was a great place to raise a family and now we have to figure out why.”

How dinosaurs became extinct, video

This 8 July 2020 video says about itself:

Why the Dinosaurs’ Extinction is an Ongoing Puzzle | Nat Geo Explores

Dinosaurs ruled the world for roughly 140 million years—until they suddenly disappeared. While decades of research point to an asteroid impact at Chicxulub crater as the end of the dinosaurs’ reign 66 million years ago, scientists weren’t always so sure what happened to these mesmerizing creatures. Theories varied wildly throughout the twentieth century as the field of paleontology grew, but it wasn’t until the 1980s that one theory emerged as a major breakthrough in the extinction mystery. Today’s scientists continue to piece together the puzzle with discoveries that give us a clearer picture of what happened to the dinosaurs.