The remains of a buried pine forest at the foot of Mont Saint Genis in Southern France yield insightful information on a drastic climate change event. The pine tree stand initiated around 12,900 years ago during the relatively warm “Allerød” period, and continued growing into the cold snap of the “Younger Dryas” period. Researchers at the GFZ German Research Centre for Geosciences in Potsdam, together with international colleagues, have for the first time combined classic tree-ring width measurements with chemical (stable isotope) analyses of carbon and oxygen in tree-rings to reconstruct climate variables. Thus, they were able to calculate local soil water composition (precipitation) and relative humidity at annual time resolution. This resulted in novel insights into the hydrological variability and atmospheric circulation changes during an abrupt climate change event. The team reports about its findings in the journal Scientific Reports.

The sudden cold snap in the northern hemisphere between 12,700 and 11,600 years ago has been found in climate records from Greenland ice cores and Central European lake sediments. It was named after the mountain avens (Latin: Dryas octopetala) — an Arctic plant species that predominantly spreads during cold conditions. The discovery of fossil pines in a French river valley near Avignon now close an important knowledge gap, as they shows how the climate in the Mediterranean changed in this period. With accurate radiocarbon dating, the scientists were able to prove that the buried pines had started their growth in the warm days of the Allerød just before the Younger Dryas and had survived the sudden cold snap for several decades. They were thus witnesses of this extreme climate change.

In their analyzes, the researchers found signs of increased air mass transport from the North Atlantic. “We were surprised that about sixty years before the actual climate change, a significant alteration in the precipitation source was recognized,” says first author Maren Pauly of the GFZ. According to the results, humid air masses arriving from the Atlantic side enhanced, while rainfall originating from the Mediterranean side diminished, evidenced by a steadily increasing variability of the oxygen isotopes of the soil water. Isotopes are atoms with a different number of neutrons in the nucleus. From the ratios of light and heavy isotopes conclusions can be drawn on the origin of air masses and thus of precipitation. “Especially striking is the increase of extreme polar air surges, winter precipitation and winter storms at the beginning of the Younger Dryas,” adds Achim Brauer, Head of GFZ’s section Climate Dynamics and Landscape Evolution and Director of Department 5 at GFZ. Maren Pauly works as a PhD student in his group.

With this study, the scientists proved that it was not a change in mean temperatures that was problematic, but rather the environmental stress presumably leading to the tree die off. This stress was caused by the accumulation of extreme weather conditions in single years or even decades. In general, this study shows that periods of massive climate change can be associated with more instability in atmospheric circulation patterns, leading to greater variability on annual or decadal scales. “Here, paleoclimate research shows how it can close knowledge gaps with information from natural climate archives,” says Achim Brauer. This is also important because “we lack experience on what exactly happens during a sudden climate change, how quickly the climate can change, and what regional differences occur.”

The study was funded by the DFG project (HE 3089 / 9-1) and supported by the Helmholtz REKLIM initiative.

Reference:
Maren Pauly, Gerhard Helle, Cécile Miramont, Ulf Büntgen, Kerstin Treydte, Frederick Reinig, Frédéric Guibal, Olivier Sivan, Ingo Heinrich, Frank Riedel, Bernd Kromer, Daniel Balanzategui, Lukas Wacker, Adam Sookdeo, Achim Brauer. Subfossil trees suggest enhanced Mediterranean hydroclimate variability at the onset of the Younger Dryas. Scientific Reports, 2018; 8 (1) DOI: 10.1038/s41598-018-32251-2

Note: The above post is reprinted from materials provided by GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre.

A new analysis is shedding light on Earth’s first macroscopic animals: the 570-million-year-old, enigmatic Ediacara biota.

Ediacaran fossils have a slightly bizarre appearance not shared by any modern animal groups. For decades, researchers believed these enigmatic fossils were ecologically simple. However, borrowing a method from modern ecology — fitting species to relative abundance distributions — Vanderbilt University paleontologist Simon A.F. Darroch and his team learned that these organisms were more like modern animals than once thought.

The analyses showed that a majority of fossil assemblages bear the hallmarks of being ecologically complex, and Ediacara biota were forming complex communities tens of millions of years before the Cambrian explosion. The creatures lived partially submerged in what was once the ocean floor, some of them suspension feeding, others filter feeding, still others passively absorbing nutrition. A few were even mobile.

Complex communities are ones that comprise species competing for numerous different resources or species that create niches for others (as in many modern-day ecosystems). The team found that the signature of complex communities extends all the way back to the oldest Ediacaran fossils. In other words, as soon as macroscopic life evolved, it began forming diverse ecological communities not unlike those in the present day.

“The main impact of our work was testing between the simple and complex models for Ediacaran ecosystems,” said Darroch, an assistant professor in Vanderbilt’s Earth and Environmental Sciences Department.

“Supporting a simple model would suggest that these mysterious organisms were universally primitive, sharing the same basic ecology and all competing for the same resources,” he said. “Support for the complex model would instead suggest that they likely competed for a variety of different resources, just like modern animals. Our analyses support the complex model, illustrating that — even though they may look bizarre — these mysterious fossils may have far more in common with modern animals than we thought.”

Their paper, “High ecological complexity in benthic Ediacaran communities,” is available online today in Nature Ecology & Evolution.

The team first compiled all Ediacaran fossil data from the published literature then added a dataset collected during fieldwork in southern Namibia. These Namibian fossils are the some of the youngest from anywhere in the world and record communities that were living immediately prior to the onset of the Cambrian explosion.

The fossils formed one of the few simple communities in the analysis, suggesting that these organisms were ecologically stressed. That lends support to the idea that the Ediacara biota were gradually going extinct in the run-up to the Cambrian explosion. Although it’s an exciting idea, Darroch said, it’s only one data point and will need much more research to prove.

The team is also using 3D modeling based on the fossil record to better characterize Ediacara biota, which completely disappeared 540 million years ago — as early arthropods, mollusks and sponges began to appear.

Reference:
Simon A. F. Darroch, Marc Laflamme, Peter J. Wagner. High ecological complexity in benthic Ediacaran communities. Nature Ecology & Evolution, 2018; DOI: 10.1038/s41559-018-0663-7

Note: The above post is reprinted from materials provided by Vanderbilt University. Original written by Heidi Hall.

Insect pollination played an important role in the evolution of angiosperms. Little is known, however, about ancient pollination insects and their niche diversity during the pre-angiosperm period due to the rarity of fossil evidence of plant-pollinator interactions.

Recently, a research group led by Prof. Wang Bo from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) has provided new insight into the niche diversity, chemical communication, and defense mechanisms of Mesozoic pollinating insects. Its findings were published in Nature Communications on September 17.

One of the most intensely investigated examples of pollination niches is the morphological match between insect proboscis and floral tube length, which Darwin described in a publication in 1877. Kalligrammatid lacewings are among the largest and most conspicuous Mesozoic insects with siphoning mouthparts.

The NIGPAS researchers reported 27 well-preserved kalligrammatids from late Cretaceous Burmese amber (99 Ma) and Chinese Early Cretaceous (125 Ma) and Middle Jurassic (165 Ma) compression rocks.

Kalligrammatid proboscides vary greatly in length, from 0.6 to 3.2 mm in amber inclusions and about 5 to 18 mm in compression fossils. The high diversity of kalligrammatids and large variation in proboscis length strongly suggest diverse plant hosts with different floral tube lengths. Therefore, pollination niche partitioning may have been present among some Mesozoic insects.

If pollination niches were partitioned, as in extant ecosystems, this likely increased pollination effectiveness and reduced the cost of pollination mutualism, thus contributing to the high diversity of pollinating insects and the success of pollinator-dependent plants during the Cretaceous period.

Kalligrammatid species diversification was potentially promoted by coevolution between pollinating kalligrammatids and their host plants under highly partitioned pollination niches.

Traits such as wing eyespots, which likely functioned as a defense in large-sized species, and sexually dimorphic antennae, which were likely used for pre-mating chemical communication, elucidate how kalligrammatids survived in the Mesozoic terrestrial ecosystem under intense competition.

However, such elaborate associations between kalligrammatids and their host plants (mostly confined to gymnosperms) could have been a key factor contributing to the extinction of kalligrammatids, which likely occurred during the late Cretaceous with the decline in gymnosperm diversity.

Reference:
Qing Liu et al, High niche diversity in Mesozoic pollinating lacewings, Nature Communications (2018). DOI: 10.1038/s41467-018-06120-5

Note: The above post is reprinted from materials provided by Chinese Academy of Sciences.

Stephen Pates, a researcher from Oxford University’s Department of Zoology, has uncovered secrets from the ancient oceans.

With Dr. Rudy Lerosey-Aubril from New England University (Australia), he meticulously re-examined fossil material collected over 25 years ago from the mountains of Utah, USA. The research, published in a new study in Nature Communications, reveals further evidence of the great complexity of the oldest animal ecosystems.

Twenty hours of work with a needle on the specimen while submerged underwater exposed numerous, delicate microscopic hair-like structures known as setae. This revelation of a frontal appendage with fine filtering setae has allowed researchers to confidently identify it as a radiodont – an extinct group of stem arthropods and distant relatives of modern crabs, insects and spiders.

“Our new study describes Pahvantia hastasta, a long-extinct relative of modern arthropods, which fed on microscopic organisms near the ocean’s surface,” says Stephen Pates. “We discovered that it used a fine mesh to capture much smaller plankton than any other known swimming animal of comparable size from the Cambrian period. This shows that large free-swimming animals helped to kick-start the diversification of life on the sea floor over half a billion years ago.”

Causes of the Cambrian Explosion—the rapid appearance in the fossil record of a diverse animal fauna around 540-500 million years ago—remain hotly debated. Although it probably included a combination of environmental and ecological factors, the establishment of a system to transfer energy from the area of primary production (the surface ocean) to that of highest diversity (the sea floor) played a crucial role.

Even though relatively small for a radiodont (FIG), Pahvantia was 10-1000 times larger than any mesoplanktonic primary consumers, and so would have made the transfer of energy from the surface oceans to the deep sea much more efficient. Primary producers such as unicellular algae are so small that once dead they are recycled locally and do not reach the deep ocean. In contrast large animals such as Pahvantia, which fed on them, produce large faecal pellets and carcasses, which sink rapidly and reached the seafloor, where they become food for bottom-dwelling animals.

Amateur enthusiasts provide research gold-dust

The presence of Pahvantia in the Cambrian of Utah has been known for decades thanks to the efforts of local amateur collectors Bob Harris and the legendary Gunther family.

“This work also provides an opportunity to celebrate the exceptional contribution of local and amateur collectors to modern palaeontology,” explains Stephen. “Without their tireless efforts, knowledge, and generosity, thousands of specimens representing hundreds of new species, would not be known to science.”

Bob Harris is rumoured to have turned down a job offer from the CIA, instead opening up a fossil shop and a number of quarries in the spectacular House Range, Utah. He discovered the first specimens of Pahvantia in the 1970s, and donated them to Richard Robison, a leading expert on Cambrian life from the University of Kansas. The Gunther family are famous for their extensive fossil collecting in Utah and Nevada. Over a dozen species have been named in honour of their contributions to palaeontology, as they have shared thousands of specimens with museums and schools over the years. Among these were specimens of Pahvantia which they uncovered between 1987 and 1997. Donated to the Kansas University Museum of Invertebrate Paleontology (KUMIP), these specimens are described for the first time in our study.

“I visited the KUMIP in the first year of my Ph.D.,” says Stephen. “It was awesome, exploring such a fantastic collection of fossils from the Cambrian of Utah and Nevada.”

The study has produced the most up-to-date analysis of evolutionary relationships between radiodonts. It shows that filter feeding evolved twice, possibly three times in this group, which otherwise essentially comprised fearsome predators such as Anomalocaris canadensis from the Burgess Shale in Canada.

Pahvantia adds to an ever-growing body of evidence that radiodonts were vital in the structure of Cambrian ecosystems, in this case linking the primary producers of the surface waters to the highly diverse fauna on the sea floor. It also shows the importance of museum collections like the KUMIP, and local collectors, such as Bob Harris and the Gunther family, in uncovering new and exciting findings about early animal life.

Reference:
Rudy Lerosey-Aubril et al. New suspension-feeding radiodont suggests evolution of microplanktivory in Cambrian macronekton, Nature Communications (2018). DOI: 10.1038/s41467-018-06229-7

Note: The above post is reprinted from materials provided by University of Oxford.

Analysis of bones, from what was once the world’s largest bird, has revealed that humans arrived on the tropical island of Madagascar more than 6,000 years earlier than previously thought — according to a study published today, 12 September 2018, in the journal Science Advances.

A team of scientists led by international conservation charity ZSL (Zoological Society of London) discovered that ancient bones from the extinct Madagascan elephant birds (Aepyornis and Mullerornis) show cut marks and depression fractures consistent with hunting and butchery by prehistoric humans. Using radiocarbon dating techniques, the team were then able to determine when these giant birds had been killed, reassessing when humans first reached Madagascar.

Previous research on lemur bones and archaeological artefacts suggested that humans first arrived in Madagascar 2,400-4,000 years ago. However, the new study provides evidence of human presence on Madagascar as far back as 10,500 years ago — making these modified elephant bird bones the earliest known evidence of humans on the island.

Lead author Dr James Hansford from ZSL’s Institute of Zoology said: “We already know that Madagascar’s megafauna — elephant birds, hippos, giant tortoises and giant lemurs — became extinct less than 1,000 years ago. There are a number of theories about why this occurred, but the extent of human involvement hasn’t been clear.

“Our research provides evidence of human activity in Madagascar more than 6,000 years earlier than previously suspected — which demonstrates that a radically different extinction theory is required to understand the huge biodiversity loss that has occurred on the island. Humans seem to have coexisted with elephant birds and other now-extinct species for over 9,000 years, apparently with limited negative impact on biodiversity for most of this period, which offers new insights for conservation today.”

Co-author Professor Patricia Wright from Stony Brook University said: “This new discovery turns our idea of the first human arrivals on its head. We know that at the end of the Ice Age, when humans were only using stone tools, there were a group of humans that arrived on Madagascar. We do not know the origin of these people and won’t until we find further archaeological evidence, but we know there is no evidence of their genes in modern populations. The question remains — who these people were? And when and why did they disappear?”

The bones of the elephant birds studied by this project were originally found in 2009 in Christmas River in south-central Madagascar — a fossil ‘bone bed’ containing a rich concentration of ancient animal remains. This marsh site could have been a major kill site, but further research is required to confirm.

Reference:
James Hansford, Patricia C. Wright, Armand Rasoamiaramanana, Ventura R. Pérez, Laurie R. Godfrey, David Errickson, Tim Thompson, Samuel T. Turvey. Early Holocene human presence in Madagascar evidenced by exploitation of avian megafauna. Science Advances, 2018; 4 (9): eaat6925 DOI: 10.1126/sciadv.aat6925

Note: The above post is reprinted from materials provided by Zoological Society of London.

Biological anthropologists from The University of Texas at Austin have described three new species of fossil primates that were previously unknown to science. All of the new primates were residents of San Diego County at a time when southern California was filled with lush tropical forests.

Since the 1930s, numerous primate fossils have been uncovered in the sandstones and claystones that make up the Friars Formation in San Diego County. Paleontologist Stephen Walsh and fieldworkers from the San Diego Museum of Natural History (SDNHM) built up a large collection of fossil primates from the San Diego area, but Walsh was unable to describe these specimens before his death in 2007.

A decade later, UT Austin graduate student Amy Atwater and anthropology professor Chris Kirk took up the challenge, describing and naming three previously unknown omomyoid primates that lived 42 million to 46 million years ago. The researchers named these new species Ekwiiyemakius walshi, Gunnelltarsius randalli and Brontomomys cerutti.

These findings double the number of known primate genera represented in the Friars Formation and increase the total number of known omomyine primates of that period from 15 to 18.

Atwater and Kirk’s descriptions were published in the Journal of Human Evolution.

“The addition of these primates provides for a better understanding of primate richness in the middle Eocene,” said Atwater, who is now the paleontology collection manager at the Museum of the Rockies in Bozeman, Montana. “Previous research in the Rocky Mountain basins suggested the primate richness declined during this time period, but we argue that primate richness increased concurrently in other locations.”

Studying the teeth, researchers concluded the three new genera, which represent the bulk of the undescribed Friars Formation omomyoid sample at SDNHM, range in size from 113 to 796 grams and are most likely related to a group of extinct species comprising the primate subfamily Omomyinae.

“Teeth can tell us a lot about evolutionary history and give us a good handle on the size and diet of an extinct primate,” Kirk said. “Enamel is the hardest tissue in the body. And as a result, teeth are more likely to be preserved in the fossil record.”

Ekwiiyemakius walshi, the smallest of the three new species, was estimated to weigh between 113 and 125 grams — comparable in size to some modern bushbabies. It was named for Walsh, who collected and prepared many of the specimens, and also derives from the Native American Kumeyaay tribe’s place name, Ekwiiyemak — meaning “behind the clouds” — for the location of the headwaters of the San Diego and Sweetwater Rivers.

Gunnelltarsius randalli was named for Gregg Gunnell, the researchers’ late colleague and expert on Eocene mammals, and for SDNHM fossil collections manager Kesler Randall. It was estimated to weigh between 275 and 303 grams, about the size of today’s fat-tailed dwarf lemur.

Brontomomys cerutti was large compared with most other omomyoids and was estimated to weigh between 719 and 796 grams — about the size of a living sportive lemur. Due to its large size, its name derives from the Greek word bront?, or “thunder,” as well as for Richard Cerutti, the retired SDNHM paleontologist responsible for collecting many of the Brontomomys specimens.

Reference:
Amy L. Atwater, E. Christopher Kirk. New middle Eocene omomyines (Primates, Haplorhini) from San Diego County, California. Journal of Human Evolution, 2018; DOI: 10.1016/j.jhevol.2018.04.010

Note: The above post is reprinted from materials provided by University of Texas at Austin.

Compared with the rest of the animal kingdom, mammals have the biggest brains and produce some of the smallest litters of offspring. A newly described fossil of an extinct mammal relative — and her 38 babies — is among the best evidence that a key development in the evolution of mammals was trading brood power for brain power.

The find is among the rarest of the rare because it contains the only known fossils of babies from any mammal precursor, said researchers from The University of Texas at Austin who discovered and studied the fossilized family. But the presence of so many babies — more than twice the average litter size of any living mammal — revealed that it reproduced in a manner akin to reptiles. Researchers think the babies were probably developing inside eggs or had just recently hatched when they died.

The study, published in the journal Nature on Aug. 29, describes specimens that researchers say may help reveal how mammals evolved a different approach to reproduction than their ancestors, which produced large numbers of offspring.

“These babies are from a really important point in the evolutionary tree,” said Eva Hoffman, who led research on the fossil as a graduate student at the UT Jackson School of Geosciences. “They had a lot of features similar to modern mammals, features that are relevant in understanding mammalian evolution.”

Hoffman co-authored the study with her graduate adviser, Jackson School Professor Timothy Rowe.

The mammal relative belonged to an extinct species of beagle-size plant-eaters called Kayentatherium wellesi that lived alongside dinosaurs about 185 million years ago. Like mammals, Kayentatherium probably had hair.

When Rowe collected the fossil more than 18 years ago from a rock formation in Arizona, he thought that he was bringing a single specimen back with him. He had no idea about the dozens of babies it contained.

Sebastian Egberts, a former graduate student and fossil preparator at the Jackson School, spotted the first sign of the babies years later when a grain-sized speck of tooth enamel caught his eye in 2009 as he was unpacking the fossil.

“It didn’t look like a pointy fish tooth or a small tooth from a primitive reptile,” said Egberts, who is now an instructor of anatomy at the Philadelphia College of Osteopathic Medicine. “It looked more like a molariform tooth (molar-like tooth) — and that got me very excited.”

A CT scan of the fossil revealed a handful of bones inside the rock. However, it took advances in CT-imaging technology during the next 18 years, the expertise of technicians at UT Austin’s High-Resolution X-ray Computed Tomography Facility, and extensive digital processing by Hoffman to reveal the rest of the babies — not only jaws and teeth, but complete skulls and partial skeletons.

The 3D visualizations Hoffman produced allowed her to conduct an in-depth analysis of the fossil that verified that the tiny bones belonged to babies and were the same species as the adult. Her analysis also revealed that the skulls of the babies were like scaled-down replicas of the adult, with skulls a tenth the size but otherwise proportional. This finding is in contrast to mammals, which have babies that are born with shortened faces and bulbous heads to account for big brains.

The brain is an energy-intensive organ, and pregnancy — not to mention childrearing — is an energy-intensive process. The discovery that Kayentatherium had a tiny brain and many babies, despite otherwise having much in common with mammals, suggests that a critical step in the evolution of mammals was trading big litters for big brains, and that this step happened later in mammalian evolution.

“Just a few million years later, in mammals, they unquestionably had big brains, and they unquestionably had a small litter size,” Rowe said.

The mammalian approach to reproduction directly relates to human development — including the development of our own brains. By looking back at our early mammalian ancestors, humans can learn more about the evolutionary process that helped shape who we are as a species, Rowe said.

“There are additional deep stories on the evolution of development, and the evolution of mammalian intelligence and behavior and physiology that can be squeezed out of a remarkable fossil like this now that we have the technology to study it,” he said.

Funding for the research was provided by the National Science Foundation, The University of Texas Geology Foundation and the Jackson School of Geosciences.

Reference:
Eva A. Hoffman, Timothy B. Rowe. Jurassic stem-mammal perinates and the origin of mammalian reproduction and growth. Nature, 2018; DOI: 10.1038/s41586-018-0441-3

Note: The above post is reprinted from materials provided by University of Texas at Austin.