International team of scientists launches fossil database
Have you ever wondered exactly when a certain group of plants or animals first evolved? This week a groundbreaking new resource for scientists will go live, and it is designed to help answer just those kinds of questions. The Fossil Calibration Database, a free, open-access resource that stores carefully vetted fossil data, is the result of years of work from a worldwide team led by Dr. Daniel Ksepka, Curator of Science at the Bruce Museum in Greenwich, and Dr. James Parham, Curator at the John D. Cooper Archaeological and Paleontological Center in Orange County, California, funded through the National Evolutionary Synthesis Center (NESCent).
“Fossils provide the critical age data we need to unlock the timing of major evolutionary events,” says Dr. Ksepka. “This new resource will provide the crucial fossil data needed to calibrate ‘molecular clocks’ which can reveal the ages of plant and animal groups that lack good fossil records. When did groups like songbirds, flowering plants, or sea turtles evolve? What natural events were occurring that may have had an impact? Precisely tuning the molecular clock with fossils is the best way we have to tell evolutionary time.”
More than twenty paleontologists, molecular biologists, and computer programmers from five different countries contributed to the design and implementation of this new database. The Fossil Calibrations Database webpage launches on Tuesday February 24th, and a series of five peer-reviewed papers and an editorial on the topic will appear in the scientific journal Palaeontologia Electronica, describing the endeavor. Dr. Ksepka is the author of one of the papers and co-author of the editorial.
“This exciting field of study, known as ‘divergence dating,’ is important for understanding the origin and evolution of biodiversity, but has been hindered by the improper use of data from the fossil record,” says Dr. Parham. “The Fossil Calibration Database addresses this issue by providing molecular biologists with paleontologist-approved data for organisms across the Tree of Life.”
The Tree of Life? “Think of it as a family tree of all species,” explains Dr. Ksepka.
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The above story is based on materials provided by Bruce Museum. Note: Materials may be edited for content and length.
Plants survive better through mass extinctions than animals
At least 5 mass extinction events have profoundly changed the history of life on Earth. But a new study led by researchers at the University of Gothenburg shows that plants have been very resilient to those events.
For over 400 million years, plants have played an essential role in almost all terrestrial environments and covered most of the world’s surface. During this long history, many smaller and a few major periods of extinction severely affected Earth’s ecosystems and its biodiversity.
In the upcoming issue of the journal New Phytologist, the team reports their results based on more than 20,000 plant fossils with the aim to understand the effects of such dramatic events on plant diversity. Their findings show that mass extinction events had very different impacts among plant groups. Negative rates of diversification in plants (meaning that more species died out than new species were formed) were never sustained through long time periods. This indicates that, in general, plants have been particularly good at surviving and recovering through tough periods.
“In the plant kingdom, mass extinction events can be seen as opportunities for turnover leading to renewed biodiversity,” says leading author Daniele Silvestro.
Most striking were the results for the Cretaceous-Paleogene mass extinction, caused by the impact of an asteroid off the Mexican coast some 66 million years ago. This event had a great impact on the configuration of terrestrial habitats and led to the extinction of all dinosaurs except birds, but surprisingly it had only limited effects on plant diversity.
Some important plant groups, such as the gymnosperms (including pines, spruce and firs) lost a great deal of their diversity through extinction. On the other hand, flowering plants (angiosperms) did not suffer from increased extinction, and shortly after the impact they underwent a new rapid increase in their diversity. These evolutionary dynamics contributed to make flowering plants dominate today’s global diversity above all other plant groups.
“Mass extinctions are often thought as a bad thing, but they have been crucial in changing the world into how we know it today,” says senior author Alexandre Antonelli.
If that asteroid had not struck the Earth, chances are that large dinosaurs would still be hunting around, mammals would be small and hiding in caves, and humans might never have evolved.
“By studying such extreme events we are trying to learn which groups of organisms and features are more sensitive to changes, so that we can apply this knowledge to protect biodiversity in the face of on-going climate change and human deterioration of natural ecosystems,” concludes Antonelli.
Ancient rocks show life could have flourished on Earth 3.2 billion years ago
A spark from a lightning bolt, interstellar dust, or a subsea volcano could have triggered the very first life on Earth. But what happened next? Life can exist without oxygen, but without plentiful nitrogen to build genes — essential to viruses, bacteria and all other organisms — life on the early Earth would have been scarce.
The ability to use atmospheric nitrogen to support more widespread life was thought to have appeared roughly 2 billion years ago. Now research from the University of Washington looking at some of the planet’s oldest rocks finds evidence that 3.2 billion years ago, life was already pulling nitrogen out of the air and converting it into a form that could support larger communities.
“People always had the idea that the really ancient biosphere was just tenuously clinging on to this inhospitable planet, and it wasn’t until the emergence of nitrogen fixation that suddenly the biosphere become large and robust and diverse,” said co-author Roger Buick, a UW professor of Earth and space sciences. “Our work shows that there was no nitrogen crisis on the early Earth, and therefore it could have supported a fairly large and diverse biosphere.”
The results were published Feb. 16 in Nature.
The authors analyzed 52 samples ranging in age from 2.75 to 3.2 billion years old, collected in South Africa and northwestern Australia. These are some of the oldest and best-preserved rocks on the planet. The rocks were formed from sediment deposited on continental margins, so are free of chemical irregularities that would occur near a subsea volcano. They also formed before the atmosphere gained oxygen, roughly 2.3 to 2.4 billion years ago, and so preserve chemical clues that have disappeared in modern rocks.
Even the oldest samples, 3.2 billion years old — three-quarters of the way back to the birth of the planet — showed chemical evidence that life was pulling nitrogen out of the air. The ratio of heavier to lighter nitrogen atoms fits the pattern of nitrogen-fixing enzymes contained in single-celled organisms, and does not match any chemical reactions that occur in the absence of life.
“Imagining that this really complicated process is so old, and has operated in the same way for 3.2 billion years, I think is fascinating,” said lead author Eva Stüeken, who did the work as part of her UW doctoral research. “It suggests that these really complicated enzymes apparently formed really early, so maybe it’s not so difficult for these enzymes to evolve.”
Genetic analysis of nitrogen-fixing enzymes have placed their origin at between 1.5 and 2.2 billion years ago.
“This is hard evidence that pushes it back a further billion years,” Buick said. Fixing nitrogen means breaking a tenacious triple bond that holds nitrogen atoms in pairs in the atmosphere and joining a single nitrogen to a molecule that is easier for living things to use. The chemical signature of the rocks suggests that nitrogen was being broken by an enzyme based on molybdenum, the most common of the three types of nitrogen-fixing enzymes that exist now. Molybdenum is now abundant because oxygen reacts with rocks to wash it into the ocean, but its source on the ancient Earth — before the atmosphere contained oxygen to weather rocks — is more mysterious.
The authors hypothesize that this may be further evidence that some early life may have existed in single-celled layers on land, exhaling small amounts of oxygen that reacted with the rock to release molybdenum to the water.
“We’ll never find any direct evidence of land scum one cell thick, but this might be giving us indirect evidence that the land was inhabited,” Buick said. “Microbes could have crawled out of the ocean and lived in a slime layer on the rocks on land, even before 3.2 billion years ago.”
Future work will look at what else could have limited the growth of life on the early Earth. Stüeken has begun a UW postdoctoral position funded by NASA to look at trace metals such as zinc, copper and cobalt to see if one of them controlled the growth of ancient life.
Swimming reptiles make their mark in the Early Triassic
Vertebrate tracks provide valuable information about animal behavior and environments. Swim tracks are a unique type of vertebrate track because they are produced underwater by buoyant trackmakers, and specific factors are required for their production and subsequent preservation. Early Triassic deposits contain the highest number of fossil swim track occurrences worldwide compared to other epochs, and this number becomes even greater when epoch duration and rock outcrop area are taken into account.
This spike in swim track occurrences suggests that during the Early Triassic, factors promoting swim track production and preservation were more common than at any other time. Coincidentally, the Early Triassic period follows the largest mass extinction event in Earth’s history, and the fossil record indicates that a prolonged period of delayed recovery persisted throughout this time period.
During this recovery interval, sediment mixing by animals living within the substrate was minimal, especially in particularly stressful environments such as marine deltas. The general lack of sediment mixing during the Early Triassic was the most important contributing factor to the widespread production of firm-ground substrates ideal for recording and preserving subaqueous trace fossils like swim tracks.
Amber fossil links earliest grasses, dinosaurs and fungus used to produce LSD
A perfectly preserved amber fossil from Myanmar has been found that provides evidence of the earliest grass specimen ever discovered — about 100 million years old — and even then it was topped by a fungus similar to ergot, which for eons has been intertwined with animals and humans.
Ergot has played roles as a medicine, a toxin, and a hallucinogen; been implicated in everything from disease epidemics to the Salem witch trials; and more recently provided the hallucinogenic drug LSD.
Apparently both ergot and the grasses that now form most of the diet for the human race evolved together.
And if they already seemed a little scary, imagine a huge sauropod dinosaur that just ate a large portion of this psychotropic fungus, which in other animal species can cause anything from hallucinations to delirium, gangrene, convulsions or the staggers. The fungus, the grasses it lived on and dinosaurs that ate grass co-existed for millions of years.
The findings and analysis of this remarkable fossil were just published online in the journal Palaeodiversity, by researchers from Oregon State University, the USDA Agricultural Research Service and Germany.
“It seems like ergot has been involved with animals and humans almost forever, and now we know that this fungus literally dates back to the earliest evolution of grasses,” said George Poinar, Jr., an internationally recognized expert on the life forms found in amber and a faculty member in the OSU College of Science.
“This is an important discovery that helps us understand the timeline of grass development, which now forms the basis of the human food supply in such crops as corn, rice or wheat,” Poinar said. “But it also shows that this parasitic fungus may have been around almost as long as the grasses themselves, as both a toxin and natural hallucinogen.
“There’s no doubt in my mind that it would have been eaten by sauropod dinosaurs, although we can’t know what exact effect it had on them.”
Amber begins as a tree sap that can flow around small plant and animal forms and permanently preserve them, as it fossilizes into a semi-precious stone. Poinar is a world leader in examining such specimens and using them to learn more about prehistoric ecosystems.
The fungus in this grass specimen, which is now extinct, was named Palaeoclaviceps parasiticus. It’s very similar to the fungus Claviceps, commonly known as ergot. The fossil, taken from amber mines in Myanmar, dates 97-110 million years ago to the early-to-mid Cretaceous, when the land was still dominated by dinosaurs and conifers, but the earliest flowering plants, grasses and small mammals were beginning to evolve. The fossil shows a grass floret tipped by the dark fungus.
Much later in evolution, grasses would become a powerful life form on Earth, creating vast prairies, nourishing herds of animals, and eventually providing for the domestication of range animals and the cultivation of many food crops. The rise of crop agriculture changed the entire development of the human race, and it’s now estimated that grasses compose about 20 percent of global vegetation.
Researchers also noted in their report that “few fungi have had a greater historical impact on society than ergot.”
Some grasses have natural defense mechanisms, and ergot may be one of them, helping to repel herbivores. It’s bitter and not a preferred food to livestock, and it’s still a problem in cereal and grass seed production, as well as pastures and grazing land.
In animal and human history, the fungus has been known to cause delirium, irrational behavior, convulsions, severe pain, gangrenous limbs and death. In cattle it causes a disease called the “Paspalum staggers.” In the Middle Ages it sometimes killed thousands of people during epidemics when ergot-infected rye bread was more common. It’s been used as a medicine to induce abortion or speed labor in pregnant women, and one researcher — whose findings have been disputed — suggested it may have played a role in the Salem witch trials.
More than 1,000 compounds have been extracted or derived from it, some of them valuable drugs. They also included, in the mid-1900s, the powerful psychedelic compound lysergic acid diethylamide, or LSD, that is still being studied and has been widely used as an illegal recreational drug.
Ergot is strange. And a very, very old fossil now makes clear that it’s been around about as long as grass itself.
Giant rodent used incisors like tusks
The largest rodent ever to have lived may have used its front teeth just like an elephant uses its tusks, a new study led by scientists at the University of York and The Hull York Medical School (HYMS) has found.
Josephoartigasia monesi, a rodent closely related to guinea pigs, lived in South America approximately 3 million years ago. It is the largest fossil rodent ever found, with an estimated body mass of 1000 kg and was similar in size to a buffalo.
Dr Philip Cox, of the Centre for Anatomical and Human Sciences, a joint research centre of the University’s Department of Archaeology and HYMS, used computer modelling to estimate how powerful the bite of Josephoartigasia could be.
He found that, although the bite forces were very large – around 1400 N, similar to that of a tiger – the incisors would have been able to withstand almost three times that force, based on earlier estimates by co-authors, Dr Andres Rinderknecht, of The Museo Nacional de Historia Natural, Montevideo, and Dr Ernesto Blanco, of Facultad de Ciencias, Instituto de Fısica, Montevideo, who first described the fossil in 2008.
Dr Cox said: “We concluded that Josephoartigasia must have used its incisors for activities other than biting, such as digging in the ground for food, or defending itself from predators. This is very similar to how a modern day elephant uses its tusks.”
The research, which is published in the Journal of Anatomy, involved CT scanning the Josephoartigasia monesi specimen and making a virtual reconstruction of its skull. This was then subjected to finite element analysis, an engineering technique that predicts stress and strain in a complex geometric object.
Fossils from heart of Amazon provide evidence that South American monkeys came from Africa
For millions of years, South America was an island continent. Geographically isolated from Africa as a result of plate tectonics more than 65 million years ago, this continent witnessed the evolution of many unfamiliar groups of animals and plants. From time to time, animals more familiar to us today — monkeys and rodents among others — managed to arrive to this island landmass, their remains appearing abruptly in the fossil record. Yet, the earliest phases of the evolutionary history of monkeys in South America have remained cloaked in mystery. Long thought to have managed a long transatlantic journey from Africa, evidence for this hypothesis was difficult to support without fossil data.
A new discovery from the heart of the Peruvian Amazon now unveils a key chapter of the evolutionary saga of these animals. In a paper published February 4, 2015 in the scientific journal Nature, the discovery of three new extinct monkeys from eastern Peru hints strongly that South American monkeys have an African ancestry.
Co-author Dr. Ken Campbell, curator at the Natural History Museum of Los Angeles County (NHM), discovered the first of these fossils in 2010, but because it was so strange to South America, it took an additional two years to realize that it was from a primitive monkey.
Mounting evidence came as a result of further efforts to identify tiny fossils associated with the first find. For many years, Campbell has surveyed remote regions of the Amazon Basin of South America in search for clues to its ancient biological past. “Fossils are scarce and limited to only a few exposed banks along rivers during the dry seasons,” said Campbell. “For much of the year high water levels make paleontological exploration impossible.” In recent years, Campbell has focused his efforts on eastern Peru, working with a team of Argentinian paleontologists expert in the fossils of South America. His goal is to decipher the evolutionary origin of one of the most biologically diverse regions in the world.
The oldest fossil records of New World monkeys (monkeys found in South America and Central America) date back 26 million years. The new fossils indicate that monkeys first arrived in South America at least 36 million years ago. The discovery thus pushes back the colonization of South America by monkeys by approximately 10 million years, and the characteristics of the teeth of these early monkeys provide the first evidence that monkeys actually managed to cross the Atlantic Ocean from Africa.