This 18 Augustus 2019 video says about itself:
In the depths of the prehistoric Amazon lurks one of the largest predators the Earth has ever seen.
Purussaurus lived in the Miocene epoch.
This November 2017 video says about itself:
Climatic cooling during the Ordovician caused explosion of marine diversity
Read more here.
From Ohio University in the USA:
Early species developed much faster than previously thought
Landmark review of Great Ordovician Biodiversification Event
When Earth’s species were rapidly diversifying nearly 500 million years ago, that evolution was driven by complex factors including global cooling, more oxygen in the atmosphere, and more nutrients in the oceans. But it took a combination of many global environmental and tectonic changes occurring simultaneously and combining like building blocks to produce rapid diversification into new species, according to a new study by Dr. Alycia Stigall, Professor of Geological Sciences at Ohio University.
She and fellow researchers have narrowed in a specific time during an era known as the Ordovician Radiation, showing that new species actually developed rapidly during a much shorter time frame than previously thought. The Great Biodiversification Event where many new species developed, they argue, happened during the Darriwilian Stage about 465 million years ago. Their research, “Coordinated biotic and abiotic change during the Great Ordovician Biodiversification Event: Darriwilian assembly of early Paleozoic building blocks”, was published in Palaeogeography, Palaeoclimatology, Palaeoecology as part of a special issue they are editing on the Great Ordovician Biodiversification Event.
New datasets have allowed them to show that what previously looked like species development widespread over time and geography was actually a diversification pulse. Picture a world before the continents as we know them, when most of the land mass was south of the equator, with only small continents and islands in the vast oceans above the tropics. Then picture ice caps forming over the southern pole. As the ice caps form, the ocean recedes and local, isolated environments form around islands and in seas perched atop continents. In those shallow marine environments, new species develop.
Then picture the ice caps melting and the oceans rising again, with those new species riding the waves of global diversification to populate new regions. The cycle then repeats producing waves of new species and new dispersals.
Lighting the Spark of Diversification
The early evolution of animal life on Earth is a complex and fascinating subject. The Cambrian Explosion (between about 540 to 510 million years ago) produced a stunning array of body plans, but very few separate species of each, notes Stigall. But nearly 40 million years later, during the Ordovician Period, this situation changed, with a rapid radiation of species and genera during the Great Ordovician Biodiversification Event.
The triggers of the GOBE and processes that promoted diversification have been subject to much debate, but most geoscientists haven’t fully considered how changes like global cooling or increased oxygenation would foster increased diversification.
A recent review paper by Stigall and an international team of collaborators attempts to provide clarity on these issues. For this study, Stigall teamed up with Cole Edwards (Appalachian State University), a sedimentary geochemist, and fellow paleontologists Christian Mac Ørum Rasmussen (University of Copenhagen) and Rebecca Freeman (University of Kentucky) to analyze how changes to the physical earth system during the Ordovician could have promoted this rapid increase in diversity.
In their paper, Stigall and colleagues demonstrate that the main pulse of diversification during the GOBE is temporally restricted and occurred in the Middle Ordovician Darriwilian Stage (about 465 million years ago). Many changes to the physical earth system, including oceanic cooling, increased nutrient availability, and increased atmospheric oxygen accumulate in the interval leading up to the Darriwilian.
These physical changes were necessary building blocks, but on their own were not enough to light the spark of diversification.
The missing ingredient was a method to alternately connect and isolate populations of species through cycles of vicariance and dispersal. That spark finally occurs in the Darriwilian Stage when ice caps form over the south pole of the Ordovician Earth. The waxing and waning of these ice sheets caused sea level to rise and fall (similar to the Pleistocene), which provided the alternate connection and disconnection needed to facilitate rapid diversity accumulation.
Stigall and her collaborators compared this to the assembly of building blocks required to pass a threshold.
This 2017 video from Florida in the USA says about itself:
The gods of birding and photography were with me on this day. I stopped to capture some shots of a Crested Caracara Family feeding on a carcass in an open field. They were soon in competition with a Vulture and then a Bald Eagle. It was amazing to witness.
Extinct Caribbean bird yields DNA after 2,500 years in watery grave
August 15, 2019
Scientists have recovered the first genetic data from an extinct bird in the Caribbean, thanks to the remarkably preserved bones of a Creighton’s caracara from a flooded sinkhole on Great Abaco Island.
Studies of ancient DNA from tropical birds have faced two formidable obstacles. Organic material quickly degrades when exposed to heat, light and oxygen. And birds’ lightweight, hollow bones break easily, accelerating the decay of the DNA within.
But the dark, oxygen-free depths of a 100-foot blue hole known as Sawmill Sink provided ideal preservation conditions for the bones of Caracara creightoni, a species of large carrion-eating falcon that disappeared soon after humans arrived in the Bahamas about 1,000 years ago.
Florida Museum of Natural History postdoctoral researcher Jessica Oswald extracted and sequenced genetic material from a 2,500-year-old C. creightoni femur from the blue hole. Because ancient DNA is often fragmented or missing, Oswald had modest expectations for what she would find — maybe one or two genes. But instead, the bone yielded 98.7% of the bird’s mitochondrial genome, the set of DNA that most living things inherit only from their mothers.
“I was super excited. I would have been happy to get that amount of coverage from a fresh specimen,” said Oswald, lead author of a study describing the work and also a postdoctoral researcher at the University of Nevada, Reno. “Getting DNA from an extinct bird in the tropics is significant because it hasn’t been successful in many cases or even tried.”
The mitochondrial genome showed that C. creightoni is closely related to the two remaining caracara species alive today: the crested caracara, Caracara cheriway, and the southern caracara, Caracara plancus. The three species last shared a common ancestor between 1.2 and 0.4 million years ago.
At least six species of caracara once cleaned carcasses and picked off small prey in the Caribbean. But the retreat of glaciers 15,000 years ago and the resulting rise in sea levels triggered extinctions of many birds, said David Steadman, Florida Museum curator of ornithology.
C. creightoni managed to survive the sweeping climatic changes, but the arrival of people on the islands ultimately heralded the species’ demise, as the tortoises, crocodiles, iguanas and rodents that the caracara depended on for food swiftly disappeared.
“This species would still be flying around if it weren’t for humans,” Steadman said. “We’re using ancient DNA to study what should be modern biodiversity.”
Today, the islands host only a fraction of the wildlife that once flourished in the scrubland, forests and water. But blue holes like Sawmill Sink can offer a portal into the past. Researchers have collected more than 10,000 fossils from the sinkhole, representing nearly 100 species, including crocodiles, tortoises, iguanas, snakes, bats and more than 60 species of birds.
Sawmill Sink’s rich store of fossils was discovered by cave diver Brian Kakuk in 2005 in his quest for horizontal passages in the limestone. The hole was not a popular diving spot: Thirty feet below the surface lay a 20-foot-thick layer of saturated hydrogen sulfide, an opaque mass that not only smells of rotten egg, but also reacts with the freshwater above it to form sulfuric acid, which causes severe chemical burns.
After multiple attempts, Kakuk, outfitted with a rebreather system and extra skin protection, punched through the hydrogen sulfide. His lamp lit up dozens of skulls and bones on the blue hole’s floor.
Soon after, Kakuk and fellow cave diver Nancy Albury began an organized diving program in Sawmill Sink.
“This was found by someone who recognized what it was and never moved anything until it was all done right,” Steadman said.
Though the hydrogen sulfide layer presented a foul problem for divers, it provided excellent insulation for the fossils below, blocking UV light and oxygen from reaching the lower layer of water. Among the crocodile skulls and tortoise shells were the C. creightoni bones, including an intact skull.
“For birds, having an entire head of an extinct species from a fossil site is pretty mind-blowing,” Oswald said. “Because all the material from the blue hole is beautifully preserved, we thought at least some DNA would probably be there.”
Since 2017, Oswald has been revitalizing the museum’s ancient DNA laboratory, testing methods and developing best practices for extracting and analyzing DNA from fossils and objects that are hundreds to millions of years old.
Ancient DNA is a challenging medium because it’s in the process of degradation. Sometimes only a minute quantity of an animal’s original DNA — or no DNA at all — remains after bacteria, fungi, light, oxygen, heat and other environmental factors have broken down an organism.
“With ancient DNA, you take what you can get and see what works,” Oswald said. “Every bone has been subjected to slightly different conditions, even relative to other ones from the same site.”
To maximize her chance of salvaging genetic material, Oswald cleans a bone, freezes it with liquid nitrogen and then pulverizes it into powder with a rubber mallet.
“It’s pretty fun,” she said.
While previous studies required large amounts of bone, Oswald’s caracara work showed ancient DNA could be successfully recovered at a smaller scale.
“This puts an exclamation point on what’s possible with ancient DNA,” said Robert Guralnick, Florida Museum curator of bioinformatics. “We have new techniques for looking at the context of evolution and extinction. Beyond the caracara, it’s cool that we have an ancient DNA lab that’s going to deliver ways to look at questions not only from the paleontological perspective, but also at the beginnings of a human-dominated planet.”
Steadman, who has spent decades researching modern and extinct biodiversity in the Caribbean, said some questions can only be answered with ancient DNA.
“By understanding species that weren’t able to withstand human presence, it helps us better appreciate what we have left — and not just appreciate it, but understand that when these species evolved, there were a lot more things running and flying around than we have today.”
Other co-authors are Julia Allen of the University of Nevada, Reno; Kelsey Witt of the University of California, Merced; Ryan Folk of the Florida Museum and Nancy Albury of the National Museum of the Bahamas.
This 15 August 2019 video says about itself:
Exceptionally Detailed Fossil [Crane-]Fly Eyes Discovered In Denmark
The ancient eyes, each just 1.25mm across, belonged to a tiny crane-fly that lived 54 million years ago. Discovered by Lund University researchers, evidence of pigment within them is shedding new light on the evolution of compound eyes.
From Lund University in Sweden:
Composition of fossil insect eyes surprises researchers
August 15, 2019
Eumelanin — a natural pigment found for instance in human eyes — has, for the first time, been identified in the fossilized compound eyes of 54-million-year-old crane-flies. It was previously assumed that melanic screening pigments did not exist in arthropods.
“We were surprised by what we found because we were not looking for, or expecting it,” says Johan Lindgren, an Associate Professor at the Department of Geology, Lund University, and lead author of the study published this week in the journal Nature.
The researchers went on to examine the eyes of living crane-flies, and found additional evidence for eumelanin in the modern species as well.
By comparing the fossilized eyes with optic tissues from living crane-flies, the researchers were able to look closer at how the fossilization process has affected the conservation of compound eyes across geological time.
The fossilized eyes further possessed calcified ommatidial lenses, and Johan Lindgren believes that this mineral has replaced the original chitinous material.
This, in turn, led the researchers to conclude that another widely held hypothesis may need to be reconsidered. Previous research has suggested that trilobites — an exceedingly well-known group of extinct seagoing arthropods — had mineralized lenses in life.
“The general view has been that trilobites had lenses made from single calcium carbonate crystals. However, they were probably much more similar to modern arthropods in that their eyes were primarily organic,” says Johan Lindgren.
Compound eyes are found in arthropods, such as insects and crustaceans, and are the most common visual organ seen in the animal kingdom. They are made up of multiple tiny and light-sensitive ommatidia, and the perceived image is a combination of inputs from these individual units.
This 2016 video from England says about itself:
How to bring a dinosaur to life in technicolour | Natural History Museum [in London]
A science team from the University of Bristol and palaeoartist Robert Nicholls have created a life-size model of Psittacosaurus featuring real colour patterns. Discover how they did this and what it tells us about the tiny dinosaur’s life 130 million years ago. Find out about fossil evidence of colour in the Museum‘s Colour and Vision exhibition (open until 6 November 2016).
From the University of Bristol in England:
Dinosaur brains from baby to adult
August 15, 2019
New research by a University of Bristol palaeontology post-graduate student has revealed fresh insights into how the braincase of the dinosaur Psittacosaurus developed and how this tells us about its posture.
Psittacosaurus was a very common dinosaur in the Early Cretaceous period — 125 million years ago — that lived in eastern Asia, especially north-east China.
Hundreds of samples have been collected which show it was a beaked plant-eater, an early representative of the Ceratopsia, which had later relatives with great neck frills and face horns, such as Triceratops.
The babies hatched out as tiny, hamster-sized beasts and grew to two metres long as adults.
As they grew, the brain changed in shape, from being crammed into the back of the head, behind the huge eyes in the hatchling, to being longer, and extending under the skull roof in the adults.
The braincase also shows evidence for a change in posture as the animals grew. There is good evidence from the relative lengths of the arms and legs, that baby Psittacosaurus scurried about on all fours, but by the age of two or three, they switched to a bipedal posture, standing up on their elongate hind legs and using their arms to grab plant food.
Claire Bullar from the University of Bristol’s School of Earth Sciences led the new research which has been published this week in PeerJ.
She said: “I was excited to see that the orientation of the semi-circular canals changes to show this posture switch.
“The semi-circular canals are the structures inside our ears that help us keep balance, and the so-called horizontal semi-circular canal should be just that — horizontal — when the animal is standing in its normal posture.
“This is just what we see, with the head of Psittacosaurus pointing down and forwards when it was a baby — just right for moving on all-fours. Then, in the teen or adult, we see the head points exactly forwards, and not downwards, just right for a biped.”
Co-supervisor Dr Qi Zhao from the Institute of Vertebrate Palaeontology and Palaeoanthropology (IVPP) in Beijing, where the specimens are housed, added: “It’s great to see our idea of posture shift confirmed, and in such a clear-cut way, from the orientation of the horizontal ear canal.
“It’s also amazing to see the results of high-quality CT scanning in Beijing and the technical work by Claire to get the best 3D models from these scan data.”
Professor Michael Ryan of Carleton University, Ottawa, Canada, another collaborator, said: “This posture shift during growth from quadruped to biped is unusual for dinosaurs, or indeed any animal. Among dinosaurs, it’s more usual to go the other way, to start out as a bipedal baby, and then go down on all fours as you get really huge.
“Of course, adult Psittacosaurus were not so huge, and the shift maybe reflects different modes of life: the babies were small and vulnerable and so probably hid in the undergrowth, whereas bipedalism allowed the adults to run faster and escape their predators.”
Professor Michael Benton, also from the University of Bristol’s School of Earth Sciences and another collaborator, added: “This is a great example of classic, thorough anatomical work, but also an excellent example of international collaboration.
“The Bristol Palaeobiology Research Group has a long-standing collaboration with IVPP, and this enables the mix of excellent specimens and excellent research.
“Who would have imagined we could reconstruct posture of dinosaurs from baby to adult, and with multiple lines of evidence to confirm we got it right.”
This 14 August 2019 video says about itself:
Was This Dinosaur a Cannibal?
Paleontologists have spent the better part of two decades debating whether Coelophysis ate its own kind. It turns out, the evidence that scientists have had to study in order to answer that question includes some of the strangest and grossest fossils that any expert would ever get to see.
This 5 February 2018 video from Britain says about itself:
New small reptile species that lived 205 million years ago discovered in a quarry in South Wales
Fossils discovered in a quarry in South Wales have been identified as a new small species of reptile that lived 205 million years ago. The species has been called Clevosaurus cambrica, the second part is Latin and refers to the fact that it comes from Wales.
They belong to a new species of Clevosaurus (Gloucester lizard), named in 1939 after Clevum, the Latin name of Gloucester.
We compared it with other examples of Clevosaurus from places around Bristol and South Gloucestershire, but our new beast is quite different in the arrangement of its teeth. In the Late Triassic period, the foothills of south Wales and southwest England formed an archipelago that was inhabited by small dinosaurs and relatives of the tuatara, a reptilian ‘living fossil’ from New Zealand. The limestone quarries of the region have many caves or fissures that contain sediments filled with bones of small species of reptiles that collapsed at the feet of dinosaurs.
Now, another relative of these reptiles, found far from Wales.
From Midwestern University in the USA:
In the shadow of the dinosaurs
A new sphenodontian from Brazil is the oldest record of the group in Gondwana
August 14, 2019
Research published this Wednesday (August 14th) in Scientific Reports describes Clevosaurus hadroprodon, a new reptile species from Rio Grande do Sul state in southern Brazil. Its fossils remains — jaws and associated skull bones — were collected from Triassic rocks (c. 237-228 million-years old) making it the oldest known fossil of its kind in Gondwana, the southern supercontinent that would eventually become Africa, Antarctica, Australia, India, and South America.
Clevosaurus hadroprodon was a small animal, similar in size with common house geckos. It belongs to the Sphenodontia, a group of lepidosaurs (which also includes snakes, lizards and amphisbaenians), that was very diverse and widespread during the Mesozoic era (the “Age of Dinosaurs”), but today has only one remaining living species in New Zealand. Clevosaurus hadroprodon is the oldest member of the Clevosauridae, a group of small sphenodonts that were the first globally distributed lepidosaurs with fossils from the Late Triassic and Early Jurassic of North America, Europe, Asia, Africa and South America.
The dentition of Clevosaurus hadroprodon is an unexpected mix of primitive and derived teeth. It is the oldest occurrence of the typical fully acrodont dentition (teeth fused to the top of the jaw bones) of sphenodontians, but most of its teeth are relatively simple and blade-like, which differs from other, only slightly younger Clevosaurus species that possess well-developed medial-posteromedial (side-to-side) expansions of the teeth for complex grinding. “However, Clevosaurus hadroprodon also possess a large, blunt, tusk-like tooth in the first tooth position of the both premaxilla (upper jaw) and of dentary (lower jaw). This feature is typically observed only in later sphenodontian lineages” says Annie Schmaltz Hsiou, Associate Professor at the University of São Paulo and head of the study. The name “hadroprodon” is Greek for “larger first tooth” in reference to these tusk-like teeth.
“Clevosaurus hadroprodon is an important discovery because it combines a relatively primitive sphenodontian-type tooth row with the presence of massive tusk-like teeth that were possibly not for feeding, but rather used for mate competition or defense. If correct, this means that non-feeding dental specializations predated changes in the sphenodontian dentition related to feeding strategies. This is a very exciting discovery.” says co-author Randall Nydam, Professor at Midwestern University (US).
In addition to its unique dentition, the authors stress that Clevosaurus hadroprodon also adds to the growing evidence that the early diversification of sphenodontians occurred in the widely separated regions of Gondwana destined to become South American and India. This illustrates the importance of the role of the Gondwanan lepidosaur fauna in our growing understanding of the earliest stages of sphenodontian evolution and the global biogeographic distribution of lepidosaurs.