Yale researchers have identified the oldest-known, definitive members of the lizard crown group that includes all living lizards and their closest extinct relatives.
The two new species, Eoscincus ornatus and Microteras borealis, fill important gaps in the fossil record and offer tantalizing clues about the complexity and geographic distribution of lizard evolution. The new lizard "kings" are described in a study published in Nature Communications.
"This helps us time out the ages of the major living lizard and snake groups, as well as when their key anatomical features originated," said Chase Brownstein, first author of the study. Brownstein, a Yale senior, collaborated on the study with Yale paleontologists Jacques Gauthier and Bhart-Anjan S. Bhullar.
Gauthier is a professor of Earth and planetary sciences in Yale's Faculty of Arts and Science and curator at the Yale Peabody Museum of Natural History. Bhullar is an associate professor of Earth and planetary sciences and an associate curator at the Peabody Museum.
A 2-million-year-old Ecosystem in Greenland Uncovered by Environmental DNA
December 7, 2022
(Nature) Late Pliocene and Early Pleistocene epochs 3.6 to 0.8 million years ago1 had climates resembling those forecasted under future warming2. Palaeoclimatic records show strong polar amplification with mean annual temperatures of 11–19 °C above contemporary values. The biological communities inhabiting the Arctic during this time remain poorly known because fossils are rare5. Here we report an ancient environmental DNA (eDNA) record describing the rich plant and animal assemblages of the Kap København Formation in North Greenland, dated to around two million years ago. The record shows an open boreal forest ecosystem with mixed vegetation of poplar, birch and thuja trees, as well as a variety of Arctic and boreal shrubs and herbs, many of which had not previously been detected at the site from macrofossil and pollen records. The DNA record confirms the presence of hare and mitochondrial DNA from animals including mastodons, reindeer, rodents and geese, all ancestral to their present-day and late Pleistocene relatives. The presence of marine species including horseshoe crab and green algae support a warmer climate than today. The reconstructed ecosystem has no modern analogue. The survival of such ancient eDNA probably relates to its binding to mineral surfaces. Our findings open new areas of genetic research, demonstrating that it is possible to track the ecology and evolution of biological communities from two million years ago using ancient eDNA.
Scientists Discovered Something Morbidly Mysterious at the Bottom of the Indian Ocean by Tessa Koumoundouros
December 11, 2022
(Science Alert) After discovering a host of bizarre creatures of the deep near Cocos (Keeling) Islands, Australia's national science agency CSIRO has found something quite surprising in the depths of the watery abyss: a shark graveyard, full of fossilized teeth, some millions of years old.
Initially, researchers thought they'd pulled up a net full of disappointing sediment and manganese nodules. Until they had a closer look.
"It was amazing, it really was," Museums Victoria Research Institute collections officer Dianne Bray tells the Australian Broadcasting Corporation (ABC).
"Not all were fossils, some were relatively recent mako sharks and two species of great white shark relatives."
More than 750 mineralized teeth, representing a range of predatory species, were hauled up from a depth of 5.4 kilometers (3.3 miles).
Researchers Uncover 92 Fossil Nests Belonging to Some of India’s Largest Dinosaurs January 19, 2023
(EurekAlert) The discovery of more than 250 fossilized eggs reveals intimate details about the lives of titanosaurs in the Indian subcontinent, according to a study published January 18, 2022 in the open-access journal PLOS ONE by Harsha Dhiman of the University of Delhi, New Delhi and colleagues.
The Lameta Formation, located in the Narmada Valley of central India, is well-known for fossils of dinosaur skeletons and eggs of the Late Cretaceous Period. Recent work in the area uncovered 92 nesting sites containing a total of 256 fossil eggs belonging to titanosaurs, which were among the largest dinosaurs to have ever lived. Detailed examination of these nests has allowed Dhiman and colleagues to make inferences about the life habits of these dinosaurs.
The authors identified six different egg-species (oospecies), suggesting a higher diversity of titanosaurs than is represented by skeletal remains from this region. Based on the layout of the nests, the team inferred that these dinosaurs buried their eggs in shallow pits like modern-day crocodiles. Certain pathologies found in the eggs, such as a rare case of an “egg-in-egg”, indicate that titanosaur sauropods had a reproductive physiology that parallels that of birds and possibly laid their eggs in a sequential manner as seen in modern birds. The presence of many nests in the same area suggests these dinosaurs exhibited colonial nesting behavior like many modern birds. But the close spacing of the nests left little room for adult dinosaurs, supporting the idea that adults left the hatchlings (newborns) to fend for themselves.
Details of dinosaur reproductive habits can be difficult to determine. These fossil nests provide a wealth of data about some of the largest dinosaurs in history, and they come from a time shortly before the age of dinosaurs came to an end. The insights gleaned from this study contribute significantly to paleontologists’ understanding of how dinosaurs lived and evolved.
Aftermath of the K-T impact, which left a crater measuring 180 km (112 mi) in diameter. This occurred around 66 million years ago in what is now southeast Mexico, and led to the extinction of the dinosaurs.
"Furious volcanism continues weeks after the event, the resulting plume wrapping around Earth. Nearby land areas are largely scoured to the bare rock by mega tsunamis, which washed over the closer secondary craters. Acrylic on illustration board."
Embers of an Ancient Inferno Pinpoint the Worst Extinction in Earth's History by
January , 2023
(Science Alert) The link between ancient volcanic eruptions and the most severe extinction event the world has ever seen just got even stronger. A new analysis of mercury isotopes has provided evidence that a quarter of a billion years ago, far-flung places in Earth's Southern Hemisphere were blanketed with debris from volcanic eruptions in Siberia.
The so-called Great Dying, also called the Permian-Triassic mass extinction event, ensued, where most of life was wiped out under ash-filled skies.
While it's clear how things ended – with the loss of more than 90 percent of marine species and over 70 percent of land-dwelling vertebrates – our understanding of how Earth's biggest die-off event unfolded remains a bit cloudy, despite geologists' best efforts.
Through piecing together chemical traces trapped in rocks and ocean sediments, geoscientists are fairly confident that a series of volcanic eruptions unleashed a cascade of dramatic changes in Earth's atmosphere and oceans that eventually suffocated animals.
But an extinction event as big as the Great Dying also needs a pretty solid case before geoscientists can definitively say what caused it, and when it happened. They are squinting back in time some 252 million years, after all.
The CT-scanned skull of a 319-million-year-old fossilized fish, pulled from a coal mine in England more than a century ago, has revealed the oldest example of a well-preserved vertebrate brain.
The brain and its cranial nerves are roughly an inch long and belong to an extinct bluegill-size fish. The discovery opens a window into the neural anatomy and early evolution of the major group of fishes alive today, the ray-finned fishes, according to the authors of a University of Michigan-led study scheduled for publication Feb. 1 in Nature.
The serendipitous find also provides insights into the preservation of soft parts in fossils of backboned animals. Most of the animal fossils in museum collections were formed from hard body parts such as bones, teeth and shells.
The CT-scanned brain analyzed for the new study belongs to Coccocephalus wildi, an early ray-finned fish that swam in an estuary and likely dined on small crustaceans, aquatic insects and cephalopods, a group that today includes squid, octopuses and cuttlefish. Ray-finned fishes have backbones and fins supported by bony rods called rays.