. Scientific Frontline: Paleontology
Showing posts with label Paleontology. Show all posts
Showing posts with label Paleontology. Show all posts

Tuesday, March 22, 2022

A sulphurous end for the dinosaurs, according to new research

Artist's impression of dinosaur extinction
Credit: James McKay
Climate cooling associated with Sulphur gases directly contributed to the extinction of the dinosaurs, research carried out at the Universities of St Andrews and Bristol has found.

The gases were ejected into the Earth’s atmosphere after a six-mile-wide asteroid hit what is now the Yucatan Peninsula, around 66 million years ago.

The research, published today in PNAS (Proceedings of the National Academy of Sciences) in collaboration with Syracuse University (New York, US), and Texas A&M explored the consequences of the asteroid impact known as the Chicxulub impact.

The research team found that Sulphur gases circulated globally for years in the Earth’s atmosphere, cooling the climate and contributing to the mass extinction of life. This extinction event was catastrophic for dinosaurs and other life but also allowed for the diversification of mammals including primates.

Dr James Witts of the School of Earth Sciences at the University of Bristol said: “Our data provides the first direct evidence for the massive amounts of Sulphur released by the Chicxulub impact. It’s amazing to be able to see such rapid and catastrophic global change in the geological record.”

Dr Aubrey Zerkle of the School of Earth and Environmental Sciences at the University of St Andrews, explained: “One reason this particular impact was so devastating to life seems to be that it landed in a marine environment that was rich in Sulphur and other volatiles. The dinosaurs were just really unlucky!”

Monday, March 21, 2022

Ancient ancestors evolved to be strong and snappy, study finds

Dunkleosteus - one of the animals involved in the study.
Credit: Nobu Tamura

Researchers, led by the University of Bristol, have shown that the earliest jaws in the fossil record were caught in a trade-off between maximizing their strength and their speed.

Almost all vertebrates are jawed vertebrates, including humans, first evolving more than 400 million years ago and distinguished by their teeth-bearing jaws. Humans owe their evolutionary success to the evolution of jaws, which allowed animals to process a wider variety of foods.

Jaws evolved from the gill arches, a series of structures in fish that support their gills. A new study, published in the journal Science Advances, explores how a breathing structure came to be a biting structure. To do this, researchers based at Bristol’s School of Earth Sciences collected data on the shapes of fossil jaws during their early evolution and mathematical models to characterize them. These models allowed the team to extrapolate a wide range of theoretical jaw shapes that could have been explored by the first evolving jaws. These theoretical jaws were tested for their strength - how likely they were to break during a bite, and their speed - how efficiently they could be opened and closed. These two functions are in a trade-off – meaning that increasing strength usually means decreasing speed or vice versa.

Wednesday, February 9, 2022

Fossils excavated in the 1960s add missing link to crocodile evolution

Credit: Gabriel Ugueto

A set of Triassic archosaur fossils, excavated in the 1960s in Tanzania, have been formally recognized as a distinct species, representing one of the earliest-known members of the crocodile evolutionary lineage.

Researchers at the University of Birmingham, the Natural History Museum and Virginia Tech University have named the animal Mambawakale ruhuhu. It is among the last to be studied of a collection of fossils dug up nearly 60 years ago from the Manda Beds, a geological formation in southern Tanzania.

The remains, which are the only known example of Mambawakale ruhuhu, include a partial skull, lower jaw, several vertebrae and a hand. From these, the research team were able to identify several distinctive features that set it apart from other archosaurs found in the Manda Beds.

These included a large skull, more than 75 cm in length, and a particularly large nostril, as well as a notably narrow lower jaw and strong variation in the sizes of the teeth at the front of the upper jaws.

Monday, January 31, 2022

New study finds some flowers unchanged for 100 million years

Flower preserved in amber
Credit: The Open University
An international research team has discovered 100-million-year-old fossil flowers preserved in amber, showing that some flowers found living today in South Africa have remained unchanged since the time of the dinosaurs.

The flowers, discovered by experts from The Open University, Qingdao University, and others, are nearly identical to those of modern Phylica species, which are part of the Cape Fynbos flora that is exposed to frequent wildfires.

The fossils were found alongside long-extinct burned plants, pointing to wildfires being an important aspect of early flower evolution.

The sudden appearance of flowering plants as fossils in middle Cretaceous time was described by Charles Darwin as an “abominable mystery” and usually, flower fossils are rare, not well preserved and come from an extinct group of species.

However, this study, published in Nature Plants, found an exception – the research team found flowers, trapped in fossil ambers, that are almost identical to plants living today near Cape Town, South Africa.

Robert A. Spicer, Emeritus Professor at The Open University, described the historical context of the flowers and what the findings can tell us about the plant evolution:

“These exquisitely preserved flowers, fruits, leaves and pollen from 100 million years ago provide a snapshot of an important time in the evolution of flowering plants, showing that early flowers were not primitive as many people suppose, but were already superbly adapted to survive the frequent wildfires that ravaged the warm ‘greenhouse’ world of the Cretaceous.

Low Volcanic Temperature Ushered in Global Cooling and the Thriving of Dinosaurs

Researchers in Japan, Sweden, and the US have unearthed evidence that low volcanic temperatures led to the fourth mass extinction, enabling dinosaurs to flourish during the Jurassic period.

Large volcanic eruptions create climatic fluctuations, ushering in evolutionary changes. Yet it is the volcanic temperature of the eruption that determines whether the climate cools or warms.

Since the emergence of early animals, five mass extinctions have taken place. The fourth mass extinction occurred at the end of the Triassic Period - roughly 201 million years ago. This mass extinction saw many marine and land animals go extinct, especially large-body, crocodilian-line reptiles known as pseudosuchia. Approximately 60-70% of animal species disappeared. As a result, small bodied dinosaurs were able to grow and prosper.

Scientists think the fourth mass extinction was triggered by the eruptions in the Central Atlantic Magmatic Province - one of the largest regions of volcanic rock. But the correlation between the eruption and mass extinction has not yet been clarified.

Tuesday, December 21, 2021

Exquisitely preserved embryo found inside fossilized dinosaur egg

Dinosaur egg and embryo reconstruction
Credit: Julius Csotonyi

A 72- to 66-million-year-old embryo found inside a fossilized dinosaur egg sheds new light on the link between the behavior of modern birds and dinosaurs, according to a new study.

The embryo, dubbed ‘Baby Yingliang’, was discovered in the Late Cretaceous rocks of Ganzhou, southern China and belongs to a toothless theropod dinosaur, or oviraptorosaur. Among the most complete dinosaur embryos ever found, the fossil suggests that these dinosaurs developed bird-like postures close to hatching.

Scientists found the posture of ‘Baby Yingliang’ unique among known dinosaur embryos — its head lies below the body, with the feet on either side and the back curled along the blunt end of the egg. Previously unrecognized in dinosaurs, this posture is similar to that of modern bird embryos.

In modern birds, such postures are related to ‘tucking’ — a behavior controlled by the central nervous system and critical for hatching success. After studying egg and embryo, researchers believe that such pre-hatching behavior, previously considered unique to birds, may have originated among non-avian theropods.

Extinct reptile discovery reveals earliest origins of human teeth, study finds

Infographic showing differentiated teeth
Credit: Dr Suresh Singh
A new extinct reptile species has shed light on how our earliest ancestors became top predators by modifying their teeth in response to environmental instability around 300 million years ago.

In findings published in Royal Society Open Science, researchers at the University of Bristol have discovered that this evolutionary adaptation laid the foundations for the incisor, canine and molar teeth that all mammals - including humans - possess today.

Shashajaia is one of the most primitive members of a group called the Sphenacodontoidea, which includes the famous sail-backed Dimetrodon, and mammal-like reptiles known as therapsids, which eventually evolved into mammals. It is remarkable for its age and anatomy, possessing a very unique set of teeth that set it apart from other synapsids – meaning the animal lineage that mammals belong to - of the time.

Dr Suresh Singh of the School of Earth Sciences explained: “The teeth show clear differentiation in shape between the front and back of the jaw, organized into distinct regions. This is the basic precursor of what mammals have today – incisors and canines up front, with molars in the back. This is the oldest record of such teeth in our evolutionary tree”.

Thursday, December 16, 2021

Theropod dinosaur jaws became stronger as they evolved

Life reconstruction of the Late Cretaceous Iren Dabasu Formation fauna, showing theropod dinosaurs of various diets
Credit: Gabriel Ugueto

Theropod dinosaurs evolved more robust jaws through time allowing them to consume tougher food, a new study reveals.

Researchers used digital modelling and computer simulation to uncover a common trend of jaw strengthening in theropods - expanding the rear jaw portion in all groups, as well as evolving an upturned jaw in carnivores and a downturned jaw in herbivores.

Publishing their findings today in Current Biology, scientists revealed that biomechanical analysis showed these form changes made jaws mechanically more stable when biting - minimizing the chance of bone fracture.

The international team, led by scientists at the University of Birmingham, created digital models of more than 40 lower jaws from five different theropod dinosaur groups, including typical carnivores like Tyrannosaurus and Velociraptor, and lesser-known herbivores like ornithomimosaurs, therizinosaurs and oviraptorosaurs.

Fion Waisum Ma, PhD researcher at the University of Birmingham, who led the study, said: “Although theropod dinosaurs are always depicted as fearsome predators in popular culture, they are in fact very diverse in terms of diets. It is interesting to observe the jaws becoming structurally stronger over time, in both carnivores and herbivores. This gives them the capacity to exploit a wider range of food items.

Friday, December 10, 2021

Dinosaurs’ Last Spring: Study Pinpoints Timing of Asteroid Impact

Credit: Florida Atlantic University/Getty Images

A groundbreaking study led by researchers at Florida Atlantic University and an international team of scientists conclusively confirms the time year of the catastrophic Chicxulub asteroid, responsible for the extinction of dinosaurs and 75 percent of life on Earth 66 million years ago. Springtime, the season of new beginnings, ended the 165-million-year reign of dinosaurs and changed the course of evolution on Earth. 

Robert DePalma (left) and Anton Oleinik, Ph.D. at the site in North Dakota.
Credit: Florida Atlantic University
Results of the study, published in the journal Scientific Reports , greatly enhances the ability to trace the first stages of damage to life on Earth. FAU’s Robert DePalma, senior author and an adjunct professor in the Department of Geosciences, Charles E. Schmidt College of Science, and a doctoral student at the University of Manchester; and Anton Oleinik, Ph.D., second author and an associate professor, FAU’s Department of Geosciences, contribute to a major scientific advancement in the ability to understand the massive impact that brought an end to the dinosaurs.

“Time of year plays an important role in many biological functions such as reproduction, feeding strategies, host-parasite interactions, seasonal dormancy, and breeding patterns,” said DePalma. “Hence, it is no surprise that the time of year for a global-scale hazard can play a big role in how harshly it impacts life. The seasonal timing of the Chicxulub impact has therefore been a critical question for the story of the end-Cretaceous extinction. Until now, the answer to that question has remained unclear.”

Wednesday, December 8, 2021

Ancient DNA found in soil samples reveals mammoths survived thousands of years longer than believed

Anthropology PhD student Tyler Murchie is a lead author on research
about a new DNA recovery technique that pulls genomes of thousands
of ancient species from less than a gram of soil.
Photo by Emil Karpinski/McMaster University
Mere spoonsful of soil pulled from Canada’s permafrost are opening vast windows into ancient life in the Yukon, revealing rich new information and rewriting previous beliefs about the extinction dynamics, dates and survival of megafauna like mammoths, horses and other long-lost life forms.

In a new paper, published in the journal Nature Communications, researchers from McMaster University, the University of Alberta, the American Museum of Natural History and the Yukon government present a 30,000-year DNA record of past environments, drawn from cored permafrost sediments extracted from the Klondike region of central Yukon.

Researchers used DNA capture-enrichment technology developed at McMaster to isolate and rebuild, in remarkable detail, the fluctuating animal and plant communities at different time points during the Pleistocene-Holocene transition, an unstable climatic period 11,000-14,000 years ago when a number of large species such as mammoths, mastodons and sabre-toothed cats disappeared.

They reconstructed the ancient ecosystems using tiny soil samples which contain billions of microscopic genomic sequences from animal and plant species.

Quetzalcoatlus, Earth’s largest flier ever

An artist’s rendition of Quetzalcoatlus northropi, a type of pterosaur and the largest flying animal that ever lived on Earth. Quetzalcoatlus stood about 12 feet tall and walked with a unique gait because of its enormous 20-foot wings, which touched the ground when folded.
Artwork courtesy of James Kuether

Look around any wetland today and you’re likely to see 3-foot-tall egrets or 4-foot-tall herons wading in the shallows in stealthy search of fish, insects or crustaceans.

But 70 million years ago, along the Rio Grande River in Texas, a more impressive and scarier creature stalked the marshes: the 12-foot-tall pterosaur known as Quetzalcoatlus. With a 37- to 40-foot wingspan, it was the largest flying animal that ever lived on Earth.

In six papers published today as a Memoir by the Society of Vertebrate Paleontology, scientists and an artist provide the most complete picture yet of this dinosaur relative, the largest example of which is represented by just a single set of fossilized bones collected in the late 1970s from Big Bend National Park. The papers describe the pterosaur’s geological and ecological setting during the Upper Cretaceous, its anatomy and taxonomic position, and how it moved on the ground and in the air.

One of the papers, co-authored by University of California, Berkeley, paleontologist Kevin Padian, emeritus professor of integrative biology and emeritus curator in the UC Museum of Paleontology, answers some of the mysteries surrounding the flying and walking behavior of this unique animal, about which little has been published since its discovery more than 45 years ago. How can an animal walk with wings so long that they touch the ground when folded? What did it eat, and how did it feed? How strong a flier was it? And how does an animal whose wings span 40 feet, yet whose legs are only 6 feet high at the hip, launch itself into the air?

Monday, November 29, 2021

Nibbling prehistoric herbivore sheds new light on Triassic diversity

Credit: Mark Witton
A Triassic herbivore, known for its supposed similarities to a modern-day ostrich, has been revealed to have entirely different approach to feeding from previously thought, according to research at the University of Birmingham.

The new discovery reveals a much broader diversity of herbivore behavior during the Triassic period than has been recognized to date.

Called Effigia, the animal was about the size of a gazelle and lived in North America around 205 million years ago. Its fossil remains were found in the Ghost Ranch Quarry in New Mexico in the 1940s, although the material was not formally described by paleontologists until 2006.

The remains had been relatively poorly preserved in the quarry and the skull, in particular, was quite badly deformed, making accurate reconstruction problematic. Early analysis of the specimen concluded that it belonged to the group of reptiles that includes crocodilians and birds and which started to flourish in the Triassic period.

Although more closely related to crocodilians, Effigia’s lightweight body, elongated neck, large eyes and beak shared many similarities with a modern-day ostrich, leading researchers to believe the animal fed by pecking plant material from the ground.

Thursday, November 11, 2021

Humans hastened the extinction of the woolly mammoth

New research shows that humans had a significant role in the extinction of woolly mammoths in Eurasia, occurring thousands of years later than previously thought.

An international team of scientists led by researchers from the University of Adelaide and University of Copenhagen, has revealed a 20,000-year pathway to extinction for the woolly mammoth.

“Our research shows that humans were a crucial and chronic driver of population declines of woolly mammoths, having an essential role in the timing and location of their extinction,” said lead author Associate Professor Damien Fordham from the University of Adelaide’s Environment Institute.

“Using computer models, fossils and ancient DNA we have identified the very mechanisms and threats that were integral in the initial decline and later extinction of the woolly mammoth.”

Signatures of past changes in the distribution and demography of woolly mammoths identified from fossils and ancient DNA show that people hastened the extinction of woolly mammoths by up to 4,000 years in some regions.

“Our research shows that humans were a crucial and chronic driver of population declines of woolly mammoths, having an essential role in the timing and location of their extinction.” 
Dr Damien Fordham
The Environment Institute, University of Adelaide

Wednesday, November 10, 2021

Rapidly evolving species more likely to go extinct, study suggests

Pleurosaurus from the Late Jurassic, some 150 million years ago, of southern Germany, a remarkable, long-bodied swimming rhynchocephalian.

Researchers at the University of Bristol have found that fast evolution can lead to nowhere.

In a new study of lizards and their relatives, Dr Jorge Herrera-Flores of Bristol’s School of Earth Sciences and colleagues have discovered that ‘slow and steady wins the race’.

Evolutionary tree of the tuatara, lizards and snakes.
During the time of the dinosaurs the extinct relatives of the
tuatara evolved rapidly, whereas lizards and snakes evolved slowly.
Credit: Dr Tom Stubbs
The team studied lizards, snakes and their relatives, a group called the Lepidosauria. Today there are more than 10,000 species of lepidosaurs, and much of their recent success is a result of fast evolution in favorable circumstances. But this was not always the case.

Mr Herrera-Flores explained: “Lepidosaurs originated 250 million years ago in the early Mesozoic Era, and they split into two major groups, the squamates on the one hand, leading to modern lizards and snakes, and the rhynchocephalians on the other, represented today by a single species, the tuatara of New Zealand. We expected to find slow evolution in rhynchocephalians, and fast evolution in squamates. But we found the opposite.”

Tuesday, November 9, 2021

Fossil elephant cranium reveals key adaptations

A remarkably well-preserved fossil elephant cranium from Kenya is helping scientists understand how its species became the dominant elephant in eastern Africa several million years ago, a time when a cooler, drier climate allowed grasslands to spread and when habitually bipedal human ancestors first appeared on the landscape. Dated to 4.5 million years ago and recovered from a site on the northeast side of Lake Turkana, it is the only well-preserved elephant cranium—the portion of the skull that encloses the brain—from that time. It is about 85% intact and holds a wealth of previously unavailable anatomical detail, according to University of Michigan paleontologist William Sanders.

Known by its museum number, KNM-ER 63642, the roughly 2-ton cranium belonged to a massive adult male of the species Loxodonta adaurora, an extinct evolutionary cousin of modern African elephants but not a direct ancestor.

Preparators from the National Museums of Kenya at the Ileret research facility of the Turkana Basin Institute, starting manual preparation and supplementing the field consolidation (chemical hardening) of Loxodonta adaurora cranium KNM-ER 63642. From left to right: Cliff Onyango, Robert Moru and Christopher Kiarie.
Image credit: Steve Jabo, Smithsonian Institution

KNM-ER 63642 is both impressively immense and unexpectedly modern in aspect, displaying adaptations that likely gave L. adaurora an edge when competing with other large mammals for grasses, according to Sanders, lead author of a study published online Oct. 21 in the journal Palaeovertebrata. Co-authors include Meave and Louise Leakey, who led the recovery effort and who are best known for the discovery of early hominid specimens and artifacts from Lake Turkana and elsewhere.

Friday, November 5, 2021

A child of darkness

The skull of the child presented in the current study was recovered during further work in the cramped spaces of the cave in 2017. The child’s skull was found alone, and no remains of its body have been recovered.

Meet Leti, a Homo naledi child discovered in the Rising Star Cave System that yielded Africa’s richest site for fossil hominins.

An international team of researchers, led by Professor Lee Berger from Wits University, has revealed the first partial skull of a Homo naledi child that was found in the remote depths of the Rising Star Cave in the Cradle of Humankind World Heritage Site near Johannesburg, South Africa.

Describing the skull and its context in two separate papers in the Open Access journal, PaleoAnthropology, the team of 21 researchers from Wits University and thirteen other universities announced the discovery of parts of the skull and teeth of the child that died almost 250,000 years ago when it was approximately four to six years old.

The first paper, of which Professor Juliet Brophy of Wits and Louisiana State Universities is lead author, describes the skull, while the second paper, of which Dr Marina Elliott, a National Geographic Explorer, is lead author, describe the context of the area and circumstances in which the skull was discovered.

Monday, November 1, 2021

Potential direct ancestor of modern humans identified

Artist rendering of Homo bodoensis
(Credit: Ettore Mazza)
A direct ancestor to modern humans has been identified, providing clarity to an important chapter in human evolution. The announcement by an international team of researchers, including a University of Hawaiʻi at Mānoa professor, was published in Evolutionary Anthropology.

Homo bodoensis lived in Africa during the Middle Pleistocene (774,000-129,000 years ago). The new name is based on a reassessment of existing fossils from Africa and Eurasia from this time period, according to co- and corresponding author Professor and Department Chair Christopher Bae from UH Mānoa’s Department of Anthropology in the College of Social Sciences.

The Middle Pleistocene is an important time period because it saw the rise of our species (Homo sapiens) in Africa and the Neanderthals (Homo neanderthalensis) in Europe. However, the time period is poorly understood, often being called the “muddle in the middle.”

“The new species, Homo bodoensis, should help to simplify the picture of human evolution during the Middle Pleistocene because it is more clearly defined, where the African fossils can easily fit,” Bae said.

Thursday, October 21, 2021

'Raptor-like’ dinosaur revealed to be a timid vegetarian

A life-reconstruction of herbivorous dinosaurs based on 220-million-year-old fossil footprints from Ipswich, Queensland, Australia.Image credit: Anthony Romilio.

The dinosaur footprint is on display at the
Queensland Museum, Brisbane.
Fossil footprints found in an Ipswich coal mine have long been thought to be that of a large ‘raptor-like’ predatory dinosaur, but scientists have found they were instead left by a timid long-necked herbivore.

University of Queensland paleontologist Dr Anthony Romilio recently led an international team to re-analyze the footprints, dated to the latter part of the Triassic Period, around 220 million-year-ago.

“For years it’s been believed that these tracks were made by a massive predator that was part of the dinosaur family Eubrontes, with legs over two meters tall,” Dr Romilio said.

“This idea caused a sensation decades ago because no other meat-eating dinosaur in the world approached that size during the Triassic period.

“But our research shows the tracks were instead made by a dinosaur from the Evazoum family – vegetarian dinosaurs that were smaller, with legs about 1.4 meters tall and a body length of six meters.”

The research team suspected there was something not-quite-right with the original size estimates and there was a good reason for their doubts.

A crab’s inland odyssey

Researchers have discovered the oldest known modern crab — trapped in amber since the time of the dinosaurs.

The 100-million-year-old fossil of the crab, Cretapsara athanata, comes from Myanmar, in Southeast Asia. It fills a major gap in the fossil record for crabs and resets the timetable for when marine crabs made their way inland.

Yale and Harvard paleontologists led the research, which appears in the journal Science Advances.

“This discovery, in a pristine and spectacular 3D preservation — including fine details of the eyes, antennae, mouthparts, and even the gills — represents the oldest evidence of incursions into land and freshwater by crabs,” said co-lead author Javier Luque, a former Yale researcher who is now a research associate at Harvard. “Crabs are primarily a marine group that only conquered land and freshwater much later, about 75 to 50 million years ago. They are largely known by bits and pieces of their claws — never in the stunning detail of our new discovery.”

The researchers said the new species, Cretapsara, was most likely neither a marine crab nor a fully terrestrial creature. Rather, Cretapsara was a freshwater-to-amphibious crab that lived either on the forest floor or in shallow bodies of water near the forest floor.

Wednesday, October 20, 2021

Extinct ground sloth was an omnivore

Julia Tejada sampling a specimen of the North American ground sloth.
(Copyright: Julia Tejada)
A study co-authored by University of Hawaiʻi at Mānoa scientists suggests that Mylodon—a ground sloth that lived in South America until about 10,000 to 12,000 years ago—was not a strict vegetarian like all of its living relatives. Based on a chemical analysis of amino acids preserved in sloth hair, the researchers uncovered evidence that this gigantic extinct sloth was an omnivore, at times eating meat or other animal protein in addition to plant matter.

Led by researchers at the American Museum of Natural History and published in Scientific Reports, the study contradicts previous assumptions about the animal and provides the first direct evidence of omnivory in an ancient sloth species.

Even though the six living sloth species all are relatively small plant-eating tree dwellers restricted to tropical forests of Central and South America, hundreds of fossil sloth species, some as large as an elephant, roamed ancient landscapes from Alaska to the southern tip of South America. Mylodon darwinii, also known as “Darwin’s ground sloth,” is thought to have weighed between 2,200 and 4,400 pounds and was nearly 10 feet long.

Based on dental characteristics, jaw biomechanics, preserved excrement from some very recent fossil species, and the fact that all living sloths exclusively eat plants, Mylodon and its extinct relatives have long been presumed to be herbivores as well. But these factors could not directly reveal whether an animal might have ingested food that requires little or no preparation and is completely digested, as happens in carcass scavenging or some other kinds of meat eating.

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