Psittacosaurus dinosaur’s camouflage colours discovered


This video from Germany says about itself:

3D camouflage in an ornithischian dinosaur

16 September 2016

We sat down in the Senckenberg Museum, Frankfurt, with Dr Jakob Vinther, University of Bristol, to examine the colour patterns of Psittacosaurus. This exquisite fossil has its skin preserved intact and so we’re able to make inferences about the environment in which it used to live.

Paper available here.

From Current Biology, 26 September 2016:

3D Camouflage in an Ornithischian Dinosaur

In Brief

Countershading camouflage uses a dark-to-light gradient from back to belly to counter the light-to-dark gradient created by illumination. The body appears flatter and less conspicuous.

Vinther et al. use 3D reconstruction and radiance modeling to show that the dinosaur Psittacosaurus was countershaded and cryptic in a forested environment.

Highlights

Preserved pigments in the dinosaur Psittacosaurus suggest countershading camouflage

We predicted the optimal countershading camouflage for different light environments

The dinosaur’s patterns would have been cryptic in a forest, but not open, habitat

We can also infer that dinosaur predators used shape-from-shading cues to detect prey

See also here.

Tyrannosaurus rex in Dutch museum, video


This 9 September 2016 Dutch video shows Tyrannosaurus rex fossil Trix, which arrived recently in Naturalis museum in Leiden in the Netherlands.

Rattlesnakes less venomous than their ancestors


This video from North America says about itself:

GoPro falls into pit of rattlesnakes

9 October 2015

Rattlesnake strikes GoPro and knocks it into pit of snakes.

From Science News in the USA:

Rattlesnakes have reduced their repertoire of venoms

Reptiles’ common ancestor possessed greater variety of toxic proteins

By Laurel Hamers

12:00pm, September 15, 2016

Modern rattlesnakes have pared down their weaponry stockpile from their ancestor’s massive arsenal. Today’s rattlers have irreversibly lost entire toxin-producing genes over the course of evolution, narrowing the range of toxins in their venom, scientists report September 15 in Current Biology.

“After going through all the work of evolving powerful toxins, over time, some snakes have dispensed with them,” says study coauthor Sean B. Carroll, an investigator with the Howard Hughes Medical Institute who is at the University of Wisconsin–Madison. These modern rattlesnakes produce smaller sets of toxins that might be more specialized to their prey.

Carroll, an evolutionary biologist, and his colleagues focused on a family of enzymes called phospholipase A2, or PLA2. Genes in the PLA2 family are one of the main sources of toxic proteins in the deadly cocktail of rattlesnake venom. This set of genes can be shuffled around, added to and deleted from to yield different collections of toxins.

Data from the genome — the complete catalog of an organism’s genetic material — can reveal how those genetic gymnastics have played out over time. Carroll’s team looked at the relevant genome regions in three modern rattlesnake species (western diamondback, eastern diamondback and Mojave) and also measured molecules that help turn genetic instructions into proteins. That showed not just how the genes were arranged, but which genes the snakes were actually using. Then, the scientists blended that data with genetic information about other closely related rattlesnakes to construct a potential evolutionary story for the loss of PLA2 genes in one group of snakes.

The most recent common ancestor of this group probably had a large suite of PLA2 genes 22 million years ago, the scientists found. That collection of genes, which probably came about through many gene duplications, coded for toxins affecting the brain, blood and muscles of the snake’s prey. But 4 million to 7 million years ago, some rattlesnake species independently dropped different combinations of those genes to get smaller and more specialized sets of venom toxins. For instance, three closely related rattlesnake species in the group lost the genes that made their venom neurotoxic.

“The surprise is [the genes’] wholesale loss at two levels: complete disappearance from the venom and complete disappearance from the genome,” Carroll says. In other words, some of the genes are still lurking in the genome but aren’t turned on. The proteins those genes produce don’t show up in the venom in modern snakes. But other genes have left the genome entirely — a more dramatic strategy than simple changes in gene regulation.

Environmental shifts might have encouraged this offloading of evolutionary baggage, Carroll says. If a certain snake species’ main food source stopped responding to a neurotoxin, the snake would waste energy producing a protein that didn’t do anything helpful.

Plus, a rattlesnake doesn’t just invest in producing venom. It also needs to produce antibodies and other proteins to protect itself from its own poison, says Todd Castoe, an evolutionary biologist at the University of Texas at Arlington who wasn’t involved in the study. As a snake’s weapon becomes more complex, its shield does too — and that protection can use up resources.

Researchers also found that venom genes might not be consistent even within a single species of rattlesnake, perhaps because snakes in different areas specialize in different prey. One western diamondback rattlesnake that Carroll’s team sampled had unexpected extra genes that the other western diamondbacks didn’t have. His lab is currently looking into these within-species differences in venom composition to see how dynamic the PLA2 genome region still is today.

As for the ancestral rattlesnake, it’s impossible to say exactly how powerful the now-extinct reptile’s venom was, Carroll says. But the wider variety of enzymes this rattlesnake could hypothetically produce would have given it more flexibility to adapt its poison to environmental curveballs — an ability that Castoe describes as “the pinnacle of nastiness.”

Editor’s note: Sean B. Carroll is on the board of trustees of Society for Science & the Public, which publishes Science News.

Saving rock iguanas on Hispaniola


This video says about itself:

Cyclura ricordi – Video Learning – WizScience.com

11 September 2015

The “Hispaniolan ground iguana“, “Ricord’s ground iguana”, “Ricord’s rock iguana”, or “Ricord’s iguana” is a critically endangered species of rock iguana.

It is found on the island of Hispaniola, and is the only known species of rock iguana to coexist with the rhinoceros iguana. Its natural habitat is dry savanna within three subpopulations in the southwestern Dominican Republic. It is threatened by habitat loss due to agricultural encroachment.

Its generic name is derived from the Ancient Greek “cyclos” meaning “circular” and “ourá” meaning “tail”, after the thick-ringed tail characteristic of all “Cyclura” iguanas. Its specific name is a Latinized form of French Biologist, Alexandre Ricord’s last name; Ricord first wrote of the species in 1826.

Morphological and genetic data indicate that the closest living relative of “C ricordi” is “C. carinata” of the Turks and Caicos Islands.

Ricord’s iguana is a large species of rock iguana with a body length of 49–51 cm in males and 40–43 cm in females with an equally long tail. Ricord’s iguana’s toes are articulated to be efficient in digging and climbing trees.

Their body color is a grayish green flat color marked by five to six bold pale gray chevrons alternating with dark gray to black chevrons. In adults, the dark chevrons are less contrasting than in juveniles. Ricord’s iguana’s eyes have a dark almost black iris and red sclera.

This species, like other species of “Cyclura”, is sexually dimorphic; males are larger than females, and have more prominent dorsal crests as well as larger femoral pores on their thighs, which are used to release pheromones.

From BirdLife:

Digging deep to save Rock Iguana

By Ali North, 13 Sep 2016

This robust, prehistoric looking species is fighting for survival with all populations covering an area of less than 100 km2.

The soil is hot to touch, the temperature reaches over 37° C in the early morning hours, and someone is covered in dust, lying face down on the ground with their head in a hole in the sand. Not an uncommon sight in certain areas of dry forest on the Caribbean island of Hispaniola.

What could at best be considered unusual behaviour, or even mistaken for illegal activity – egg stealing, a threat facing many reptiles across the globe, is a scientist – Dr Stesha Pasachnik – conducting vital research to help save a large reptile from extinction. The Ricord’s Rock Iguana Cyclura ricordii is a stocky, prehistoric looking creature that occurs in just four sub-populations on Hispaniola (an island shared by the Dominican Republic and Haiti).

Classified as Critically Endangered on the IUCN Red List, the species is fighting for its survival, with a total range of less than 100 km2 and an uncertain global population estimate of fewer than 4,000 individuals. The threats facing this island endemic are broad, and are exacerbated by its restricted range: illegal hunting, predation and disturbance by introduced mammals, agricultural expansion and charcoal production are all ramping up the pressure.

In the early 2000s, a Species Recovery Plan was developed by the IUCN and its implementation brought together five partner organisations. Grupo Jaragua (BirdLife in the Dominican Republic) was one, whose contributions have been instrumental in building a greater understanding of the species and raising environmental awareness among local communities. Ground surveys have revealed the existence of a handful of critical nesting sites, including a population in Haiti that was previously thought to be extinct. These sites, locally called fondos, are small areas with deep dirt/clay soils where the iguanas can dig and lay their eggs in synchrony with the rainy season.

One of the most dense concentrations of iguana nests is Fondo de La Tierra, a conservation area of 26 hectares purchased in 2010 by Grupo Jaragua with funding from the International Iguana Foundation. Since 2006, four fondos have seen a three-fold increase in Ricord’s Rock Iguana nest numbers. Research by Grupo Jaragua, INTEC University in Santo Domingo, Mississippi State University and San Diego Zoo’s Institute for Conservation Research is helping to better understand population size, genetics and the ecology of this and another iguana – the Vulnerable Rhinoceros Iguana Cyclura cornuta. This explains the dust-covered scientists, excavating nests to determine hatching success and retrieve temperature loggers.

Using camera traps and frequent field surveys, Grupo Jaragua has also been able to document and help control one of the many threats facing Ricord’s Rock Iguana: invasive alien species. These include cattle and donkeys (which degrade iguana habitat) and cats, dogs, and mongoose. (which prey upon iguana hatchlings and adults). President of Grupo Jaragua, Yolanda León, adds:

“We are also documenting the severe habitat destruction caused by charcoal production and have been actively involved in advocacy activities to reduce this illegal activity. We are working with journalists, filmmakers, and social media to document and expose the situation”.

Grupo Jaragua has trained 400 teachers about the species’ ecology and the importance of iguana conservation to help foster positive attitudes towards the species, while the use of native and endemic plants in an agroforestry programme, alongside the promotion of bee-keeping as a biodiversity friendly activity, is ensuring that critical habitat for iguanas, birds and other wildlife will remain for generations to come. To ensure the future of Ricord’s Rock Iguana and the habitat it relies on, conservation organisations on the island really are having to dig deep. However, through a huge collaborative effort involving research, land protection and local engagement, there is now genuine optimism that the decline can be reversed.

This is just one of many non-avian species that are the focus of work by the BirdLife Partnership across the globe. A recent survey, supported by the Aage V Jensen Charity Foundation, revealed that 74% of BirdLife Partners are conducting work that benefits or focuses on taxa beyond birds. Over 370 projects were identified worldwide, with Grupo Jaragua’s work on Ricord’s Rock Iguana being just one of over sixty projects involving reptiles.

Tyrannosaurus rex Trix in Dutch Naturalis museum


This 9 September 2016 video shows Tyrannosaurus rexTrix‘ after her arrival in Naturalis museum in Leiden in the Netherlands.

Small Cretaceous pterosaurs discovered


This video says about itself:

25 July 2014

Pterosaurs (/ˈtɛrɵsɔr/, from the Greek πτερόσαυρος, pterosauros, meaning “winged lizard”) were flying reptiles of the clade or order Pterosauria. They existed from the late Triassic to the end of the Cretaceous Period (228 to 66 million years ago).

Pterosaurs are the earliest vertebrates known to have evolved powered flight. Their wings were formed by a membrane of skin, muscle, and other tissues stretching from the ankles to a dramatically lengthened fourth finger. Early species had long, fully toothed jaws and long tails, while later forms had a highly reduced tail, and some lacked teeth. Many sported furry coats made up of hair-like filaments known as pycnofibers, which covered their bodies and parts of their wings. Pterosaurs spanned a wide range of adult sizes, from the very small Nemicolopterus to the largest known flying creatures of all time, including Quetzalcoatlus and Hatzegopteryx.

From Science News:

Pterosaurs weren’t all super-sized in the Late Cretaceous

Some of the flying reptiles were smaller than a bald eagle

By Meghan Rosen

7:00am, September 12, 2016

Pterosaurs didn’t have to be gargantuan to survive in the Late Cretaceous.

Fragmentary fossils of a roughly 77-million-year-old pterosaur found in British Columbia suggest it had a wingspan of just 1.5 meters, about a quarter that of a bald eagle.

Bald eagles have wingspans of about two meters. So, the newly discovered pterosaus were smaller than bald eagles; but not four times smaller.

The ancient flier is the smallest pterosaur discovered during this time period — by a lot, report paleontologist Elizabeth Martin-Silverstone of the University of Southampton in England and colleagues August 30 in Royal Society Open Science.

Dozens of larger pterosaurs, some with wings spanning more than 10 meters (nearly the length of a school bus), have been unearthed. But until now, scientists had found only two small-scale versions, with wingspans 2.5 to 3 meters long, from the period stretching from 66 million to 100 million years ago.

Some scientists blamed competition with birds for the scarcity of little flying reptiles. Researchers have proposed that, “the only way pterosaurs could survive was by evolving completely crazy massive sizes,” Martin-Silverstone says.

The new find, she says, may mean that, “pterosaurs were doing better than we thought.”

Tyrannosaurus rex discoverers interviewed


This 24 August 2016 video from Montana in the USA shows an interview with [Dutch born amateur paleontologist] Michele and Blaine Lunstad and ‘Dino Cowboy’ Clayton Phipps; about their discovery of Tyrannosaurus rex fossil ‘Trix‘ in May 2013. Recently, Trix arrived in Naturalis museum in Leiden in the Netherlands.