What a Bunch of Dodos! Catastrophic Mass Extinction of Birds in Pacific Islands Followed Arrival of First People
Mar. 25, 2013 — Research carried out by the Zoological Society of London (ZSL) and collaborators reveals that the last region on earth to be colonised by humans was home to more than 1,000 species of birds that went extinct soon after people reached their island homes.
Almost 4,000 years ago, tropical Pacific Islands were an untouched paradise, but the arrival of the first people in places like Hawaii and Fiji caused irreversible damage to these natural havens, due to overhunting and deforestation. As a result, birds disappeared. But understanding the scale and extent of these extinctions has been hampered by uncertainties in the fossil record.
Professor Tim Blackburn, Director of ZSL’s Institute of Zoology says: “We studied fossils from 41 tropical Pacific islands and using new techniques we were able to gauge how many extra species of bird disappeared without leaving any trace.”
They found that 160 species of non-passerine land birds (non-perching birds which generally have feet designed for specific functions, for example webbed for swimming) went extinct without a trace after the first humans arrived on these islands alone.
“If we take into account all the other islands in the tropical Pacific, as well as seabirds and songbirds, the total extinction toll is likely to have been around 1,300 bird species,” Professor Blackburn added.
Species lost include several species of moa-nalos, large flightless waterfowl from Hawai’i, and the New Caledonian Sylviornis, a relative of the game birds (pheasants, grouse, etc) but which weighed in at around 30kg, three times as heavy as a swan.
Certain islands and bird species were particularly vulnerable to hunting and habitat destruction. Small, dry islands lost more species because they were more easily deforested and had fewer places for birds to hide from hunters. Flightless birds were over 30 times more likely to become extinct that those that could fly.
Bird extinctions in the tropical Pacific did not stop with these losses. Forty more species disappeared after Europeans arrived, and many more species are still threatened with extinction today.
Strange Spaghetti-Shaped Creature Is Missing Link: Discovery Pushes Fossil Record Back 200 Million Years
Mar. 13, 2013 — Canada’s 505 million year-old Burgess Shale fossil beds, located in Yoho National Park, have yielded yet another major scientific discovery — this time with the unearthing of a strange spaghetti-shaped creature.
It’s a discovery that pushes back the fossil record of a group of creatures known as enteropneusts by 200 million years — and provides the crucial “missing link” in an important evolutionary transformation.
“Unlike animals with teeth and bones, these spaghetti-shaped creatures were soft-bodied, so the fossil record for them is extremely scarce,” said Jean-Bernard Caron, associate professor of Earth Sciences and Ecology & Evolutionary Biology at the University of Toronto and curator of invertebrate palaeontology at the Royal Ontario Museum.
“Our analysis of Spartobranchus tenuis, a creature previously unknown to science, pushes the fossil record of the enteropneusts back by 200 million years and illuminates our understanding of the early evolution of this group of organisms,” Caron said.
Caron is the lead author of the study published online in the journal Nature March 13 2013 which found Spartobranchus tenuis is a member of the acorn worms group. Acorn worms are marine animals that belong to the phylum hemichordates, a group which is closely related to todays sea stars and sea urchins. While Spartobranchus tenuis is long extinct, other species of acorn worms thrive in the fine sands and mud of deep and shallow waters in present-day ecosystems.
Since the discovery of hemichordates in the 19th century, some of the biggest questions in hemichordate evolution have focused on the group’s origins and the relationship between its two main branches: the enteropneusts and pterobranchs. Enteropneusts and pterobranchs look very different, yet share many genetic and developmental characteristics that reveal an otherwise unexpected close relationship.
“Spartobranchus tenuis represents a crucial missing link that serves not only to connect the two main hemichordate groups but helps to explain how an important evolutionary transformation was achieved,” said Caron. “Our study suggests that primitive enteropneusts developed a tubular structure — the smoking gun — which has been retained over time in modern pterobranchs.”
Hemichordates also share many of the same characteristics as chordates — a group of animals that includes humans — with the name hemichordate roughly translating to ‘half a chordate.’
Spartobranchus tenuis probably fed on small particles of matter at the bottom of the oceans.
“There are literally thousands of specimens at the Walcott Quarry in Yoho National Park, so it’s possible Spartobranchus tenuis may have played an important role in recycling organic matter in the early Burgess Shale environment, similar to the ecological service provided by earth worms today on land,” said Caron.
Detailed analysis suggests Spartobranchus tenuis (illustration at right by Marianne Collins) had a flexible body consisting of a short proboscis, collar and narrow elongate trunk terminating in a bulbous structure, which may have served as an anchor.
The largest complete specimens examined were 10 centimetres long with the proboscis accounting for about half a centimetre. A large proportion of these worms was preserved in tubes, of which some were branched, suggesting the tubes were used as a dwelling structure.
Other members of the Spartobranchus tenuis research team are Simon Conway Morris of the University of Cambridge and Christopher B. Cameron of the Université de Montréal. Last year Conway Morris and Caron published a well-publicized study on Pikaia, believed to be one of the planet’s first human relatives.
The Burgess Shale is found in Yoho National Park, part of the Canadian Rocky Mountain Parks World Heritage Site, and is one of the most important fossil deposits for understanding the origin and early evolution of animals that took place during the Cambrian Explosion starting about 542 million years ago.
Four Dinosaur Egg Species Identified in Lleida, Spain
Mar. 12, 2013 — A study headed by the Miquel Crusafont Catalan Palaeontology Institute has for the first time documented detailed records of dinosaur egg fossils in the Coll de Nargó archaeological site in Lleida, Spain. Up until now, only one type of dinosaur egg had been documented in the region
The archaeological site in Coll de Nargó containing dinosaur eggs lies some 8 kilometres to the west of the town that bears the same name in the province of Lleida. This region is home to different types of geological formations, including the Areniscas de Arén Formation and the Tremp Formation, which have provided a rich and varied yield of dinosaur fossils through the entire Pyrenees region.
“Eggshells, eggs and nests were found in abundance and they all belong to dinosaurs, sauropods in particular. Up until now, only one type of dinosaur egg had been documented in the region: Megaloolithus siruguei. After analysing more than 25 stratus throughout the Tremp Formation, a minimum of four different additional types were identified: Cairanoolithus roussetensis, Megaloolithus aureliensis, Megaloolithus siruguei and Megaloolithus baghensis,” as explained by Albert García Sellés from the Miquel Crusafont Catalan Palaeontology Institute and lead author of the study.
One of the main problems faced by palaeontologists when studying fossil remains is determining the age of the sediments that contain them. There are fossils known as “guide fossils” whose characteristics allow for the age of rocks to be deduced. However, these fossils are frequent in marine sediments but more scarce and difficult to find in land sediments.
“It has come to light that the different types of eggs (oospecies) are located at very specific time intervals. This allows us to create biochronological scales with a precise dating capacity. In short, thanks to the collection of oospecies found in Coll de Nargó we have been able to determine the age of the site at between 71 and 67 million years,” ensures the expert.
The paleontological sites in the south of Europe containing dinosaur remains have a high scientific value since they allow us to understand and thus reconstruct the ecosystems at the end of the Mesozoic Era.
The latest scientific investigations show that the dinosaur fauna of the European Continent living for a short time before the great extinction some 66 million years ago can be found exactly on the southern side of the Pyrenees.
A connection between French and Spanish dinosaurs
The discovery of Cairanoolithus fossils in this area is an important finding. Given that this type of eggs is only known in the south of France, they are the first of their kind found in the Iberian Peninsula.
According to García Sellés, this discovery constitutes a new proof of the connection between dinosaur fauna in France and in the Iberian Peninsula some 70 million years ago.
Furthermore, finding dinosaur eggs and nests in more than 25 stratigraphic levels provides clear evidence that these sauropods used the Coll de Nargó region as a nesting area for millions of years.
“We had never found so many nests in the one area before. In addition, the presence of various oospecies at the same level suggests that different types of dinosaurs shared the same nesting area,” concludes the scientist.
Light Shed on Ancient Origin of Life
Mar. 6, 2013 — University of Georgia researchers discovered important genetic clues about the history of microorganisms called archaea and the origins of life itself in the first ever study of its kind. Results of their study shed light on one of Earth’s oldest life forms.
“Archaea are an ancient form of microorganisms, so everything we can learn about them could help us to answer questions about the origin of life,” said William Whitman, a microbiology professor in the Franklin College of Arts and Sciences and co-author on the paper.
Felipe Sarmiento, lead author and doctoral student in the microbiology department, surveyed 1,779 genes found in the genome of Methanococcus maripaludis, aquatic archaea commonly found in sea marshes, to determine if they were essential or not and learn more about their functions. He found that roughly 30 percent, or 526 genes, were essential. We now know which genes are driving the most important functions of the cell. The results of the study were published March 4 in the PNAS Early Edition and were performed with Jan Mrázek, an associate professor in the department of microbiology and the UGA Institute of Bioinformatics.
Although archaea are relatively simple organisms, the genetic systems they use to build cellular life are similar to those of more complicated eukaryotic cells found in complex organisms including animals and plants. For this reason, many scientists believe that eukaryotes evolved from ancient archaea.
These genetic systems are what allow information coded on DNA to build life.
“DNA by itself is a rock,” Whitman said. “You need all these other systems to make the DNA become a living cell.”
Because DNA is so fundamental to the modern cell, DNA synthesis has long been thought to be one of the most conserved processes in living organisms.
“It was a surprise when this study found that the system for making DNA was unique to the archaea,” Whitman said. “Learning that it can change in the archaea suggest that ability to make DNA formed late in the evolution of life. Possibly, there may be unrecognized differences in DNA biosynthesis the eukaryotes or bacteria as well.”
Other essential genes in these archaea are necessary for methane production. Methanogensis, or the process of making methane gas, is how these microorganisms make energy for life.
“Humans burn glucose and reduce oxygen to water, these guys burn hydrogen gas and reduce CO2 to methane,” Whitman explained.
Methanogenesis requires six vitamins not commonly found in other organisms. Understanding how these vitamins are made and how they are involved in the process of changing carbon dioxide to methane sheds light on developing new and better processes for methane production for fuel.
“This was a general investigation, but there are many questions it can answer, like possibly making methane better or more efficiently,” Whitman said.
The study yielded many other important results.
“We found 121 proteins that are essential for this organism that we know nothing about,” Sarmiento said. “This finding asks questions about their functions and the specific roles that they are playing.”
“We are starting to get some insights about how this organism was actually formed,” Sarmiento said. “There is a lot of information and it is interesting because it gives insights into a complete domain of life.”
Remains of Extinct Giant Camel Discovered in High Arctic
Mar. 5, 2013 — A research team led by the Canadian Museum of Nature has identified the first evidence for an extinct giant camel in Canada’s High Arctic. The discovery is based on 30 fossil fragments of a leg bone found on Ellesmere Island, Nunavut and represents the most northerly record for early camels, whose ancestors are known to have originated in North America some 45 million years ago.
The fossils were collected over three summer field seasons (2006, 2008 and 2010) and are about three-and-a-half million years old, dating from the mid-Pliocene Epoch. Other fossil finds at the site suggest this High Arctic camel lived in a boreal-type forest environment, during a global warm phase on the planet.
The research by Dr. Natalia Rybczynski and co-authors including Dr. John Gosse at Dalhousie University, Halifax and Dr. Mike Buckley at the University of Manchester, England is described in the March 5, 2013 edition of the online journal Nature Communications.
“This is an important discovery because it provides the first evidence of camels living in the High Arctic region,” explains Rybczynski, a vertebrate paleontologist with the Canadian Museum of Nature, who has led numerous field expeditions in Canada’s Arctic. “It extends the previous range of camels in North America northward by about 1,200 km, and suggests that the lineage that gave rise to modern camels may been originally adapted to living in an Arctic forest environment.”
The camel bones were collected from a steep slope at the Fyles Leaf Bed site, a sandy deposit near Strathcona Fiord on Ellesmere Island. Fossils of leaves, wood and other plant material have been found at this site, but the camel is the first mammal recovered. A nearby fossil-rich locality at Strathcona Fiord, known as the Beaver Pond site, has previously yielded fossils of other mammals from the same time period, including a badger, deerlet, beaver and three-toed horse.
Determining that the bones were from a camel was a challenge. “The first time I picked up a piece, I thought that it might be wood. It was only back at the field camp that I was able to ascertain it was not only bone, but also from a fossil mammal larger than anything we had seen so far from the deposits,” explains Rybczynski, relating the moment that she and her team had discovered something unusual.
Some important physical characteristics suggested the fossil fragments were part of a large tibia, the main lower-leg bone in mammals, and that they belonged to the group of cloven-hoofed animals known as arteriodactyls, which includes cows, pigs and camels. Digital files of each of the 30 bone fragments were produced using a 3D laser scanner, allowing for the pieces to be assembled and aligned. The size of the reconstituted leg bone suggested it was from a very large mammal. At the time in North America, the largest arteriodactyls were camels.
Full confirmation that the bones belonged to a camel came from a new technique called “collagen fingerprinting” pioneered by Dr. Mike Buckley at the University of Manchester in England. Profiles produced by this technique can be used to distinguish between groups of mammals.
Minute amounts of collagen, the dominant protein found in bone, were extracted from the fossils. Using chemical markers for the peptides that make up the collagen, a collagen profile for the fossil bones was developed. This profile was compared with those of 37 modern mammal species, as well as that of a fossil camel found in the Yukon, which is also in the Canadian Museum of Nature’s collections.
The collagen profile for the High Arctic camel most closely matched those of modern camels, specifically dromedaries (camels with one hump) as well as the Yukon giant camel, which is thought to be Paracamelus, the ancestor of modern camels. The collagen information, combined with the anatomical data, allowed Rybczynski and her colleagues to conclude that the Ellesmere bones belong to a camel, and is likely the same lineage as Paracamelus.
“We now have a new fossil record to better understand camel evolution, since our research shows that the Paracamelus lineage inhabitated northern North America for millions of years, and the simplest explanation for this pattern would be that Paracamelus originated there,” explains Rybczynski. “So perhaps some specializations seen in modern camels, such as their wide flat feet, large eyes and humps for fat may be adaptations derived from living in a polar environment.”
The scientific paper also reports for the first time an accurate age of both the Fyles Leaf Bed site and the Beaver Pond site — at least 3.4 million years old. This was determined by Dr. John Gosse at Dalhousie University using a sophisticated technique that involves dating the sands found associated with the bone. The date is significant because it corresponds to a time period when Earth was 2ºC à 3ºC warmer than today, and the Arctic was 14ºC à 22ºC warmer. The bones of the High Arctic camel are housed in the Canadian Museum of Nature’s research and collections facility in Gatineau, Quebec on behalf of the Government of Nunavut.
New Fossils of Crocodilian, Hippo-Like Species from Panama
Mar. 5, 2013 — University of Florida paleontologists have discovered remarkably well-preserved fossils of two crocodilians and a mammal previously unknown to science during recent Panama Canal excavations that began in 2009.
The two new ancient extinct alligator-like animals and an extinct hippo-like species inhabited Central America during the Miocene about 20 million years ago. The research expands the range of ancient animals in the subtropics — some of the most diverse areas today about which little is known historically because lush vegetation prevents paleontological excavations — and may be used to better understand how climate change affects species dispersal today. The two studies appear online today in the same issue of the Journal of Vertebrate Paleontology.
The fossils shed new light on scientists’ understanding of species distribution because they represent a time before the formation of the Isthmus of Panama, when the continents of North and South America were separated by oceanic waters.
“In part we are trying to understand how ecosystems have responded to animals moving long distances and across geographic barriers in the past,” said study co-author Jonathan Bloch, associate curator of vertebrate paleontology at the Florida Museum of Natural History on the UF campus. “It’s a testing ground for things like invasive species — if you have things that migrated from one place into another in the past, then potentially you have the ability to look at what impact a new species might have on an ecosystem in the future.”
The research was funded by the National Science Foundation Panama Canal Partnerships in International Research and Education project, which supports paleontological excavation of the canal during construction expected to continue through 2014.
“We’re very fortunate we could get the funding for PIRE to take advantage of this opportunity — we’re getting to sample these areas that are completely unsampled,” said Alex Hastings, lead author of the crocodilian study and a visiting instructor at Georgia Southern University who conducted the research for the project as a UF graduate student.
Researchers analyzed all known crocodilian fossils from the Panama Canal, including the oldest records of Central American caimans, which are cousins of alligators. The more primitive species, named Culebrasuchus mesoamericanus, may represent an evolutionary transition between caimans and alligators, Hastings said.
“You mix an alligator and one of the more primitive caimans and you end up with this caiman that has a much flatter snout, making it more like an alligator,” Hastings said. “Before this, there were no fossil crocodilian skulls known from Central America.”
Christopher Brochu, an assistant professor of vertebrate paleontology in the department of geoscience at the University of Iowa, said “the caiman fossil record is tantalizing,” and the new data shows there is still a long way to go before researchers understand the group.
“The fossils that are in this paper are from a later time period, but some of them appear to be earlier-branching groups, which could be very important,” said Brochu, who was not involved with the study. “The problem is, because we know so little about early caiman history, it’s very difficult to tell where these later forms actually go on the family tree.”
The new mammal species researchers described is an anthracothere, Arretotherium meridionale, an even-toed hooved mammal previously thought to be related to living hippos and intensively studied on the basis of its hypothetical relationship with whales. About the size of a cow, the mammal would have lived in a semi-aquatic environment in Central America, said lead author and UF graduate student Aldo Rincon.
“With the evolution of new terrestrial corridors like this peninsula connecting North America with Central America, this is one of the most amazing examples of the different kind of paths land animals can take,” Rincon said. “Somehow this anthracothere is similar to anthracotheres from other continents like northern Africa and northeastern Asia.”
Researchers also name a second crocodilian species, Centenariosuchus gilmorei, after Charles Gilmore, who first reported evidence of crocodilian fossils collected during construction of the canal 100 years ago. The genus is named in honor of the canal’s centennial in 2014.
Researchers will continue excavating deposits from the Panama Canal during construction to widen and straighten the channel and build new locks. The project is funded by a $3.8 million NSF grant to develop partnerships between the U.S. and Panama and engage the next generation of scientists in paleontological and geological discoveries along the canal.
Study co-authors include Bruce MacFadden of UF and Carlos Jaramillo of the Smithsonian Tropical Research Institute.
New Dinosaur Species: First Fossil Evidence Shows Small Crocs Fed On Baby Dinosaurs
Feb. 28, 2013 — A South Dakota School of Mines & Technology assistant professor and his team have discovered a new species of herbivorous dinosaur and today published the first fossil evidence of prehistoric crocodyliforms feeding on small dinosaurs.
Research by Clint Boyd, Ph.D., provides the first definitive evidence that plant-eating baby ornithopod dinosaurs were a food of choice for the crocodyliform, a now extinct relative of the crocodile family. While conducting their research, the team also discovered that this dinosaur prey was a previously unrecognized species of a small ornithopod dinosaur, which has yet to be named.
The evidence found in what is now known as the Grand Staircase Escalante-National Monument in southern Utah dates back to the late Cretaceous period, toward the end of the age of dinosaurs, and was published today in the online journal PLOS ONE. The complete research findings of Boyd and Stephanie K. Drumheller, of the University of Iowa and the University of Tennessee, and Terry A. Gates, of North Carolina State University and the Natural History Museum of Utah, can be accessed online (see journal reference below).
A large number of mostly tiny bits of dinosaur bones were recovered in groups at four locations within the Utah park — which paleontologists and geologists know as the Upper Cretaceous (Campanian) Kaiparowits Formation — leading paleontologists to believe that crocodyliforms had fed on baby dinosaurs 1-2 meters in total length.
Evidence shows bite marks on bone joints, as well as breakthrough proof of a crocodyliform tooth still embedded in a dinosaur femur.
The findings are significant because historically dinosaurs have been depicted as the dominant species. “The traditional ideas you see in popular literature are that when little baby dinosaurs are either coming out of a nesting grounds or out somewhere on their own, they are normally having to worry about the theropod dinosaurs, the things like raptors or, on bigger scales, the T. rex. So this kind of adds a new dimension,” Boyd said. “You had your dominant riverine carnivores, the crocodyliforms, attacking these herbivores as well, so they kind of had it coming from all sides.”
Based on teeth marks left on bones and the large amounts of fragments left behind, it is believed the crocodyliforms were also diminutive in size, perhaps no more than 2 meters long. A larger species of crocodyliform would have been more likely to gulp down its prey without leaving behind traces of “busted up” bone fragments.
Until now, paleontologists had direct evidence only of “very large crocodyliforms” interacting with “very large dinosaurs.”
“It’s not often that you get events from the fossil record that are action-related,” Boyd explained. “While you generally assume there was probably a lot more interaction going on, we didn’t have any of that preserved in the fossil record yet. This is the first time that we have definitive evidence that you had this kind of partitioning, of your smaller crocodyliforms attacking the smaller herbivorous dinosaurs,” he said, adding that this is only the second published instance of a crocodyliform tooth embedded in any prey animal in the fossil record.
“A lot of times you find material in close association or you can find some feeding marks or traces on the outside of the bone and you can hypothesize that maybe it was a certain animal doing this, but this was only the second time we have really good definitive evidence of a crocodyliform feeding on a prey animal and in this case an ornithischian dinosaur,” Boyd said.
The high concentrations of tiny dinosaur bones led researchers to conclude a type of selection occurred, that crocodyliforms were preferentially feeding on these miniature dinosaurs. “Maybe it was closer to a nesting ground where baby dinosaurs would have been more abundant, and so the smaller crocodyliforms were hanging out there getting a lunch,” Boyd added.
“When we started looking at all the other bones, we starting finding marks that are known to be diagnostic for crocodyliform feeding traces, so all that evidence coming together suddenly started to make sense as to why we were not finding good complete specimens of these little ornithischian dinosaurs,” Boyd explained. “Most of the bites marks are concentrated around the joints, which is where the crocodyliform would tend to bite, and then, when they do their pulling or the death roll that they tend to do, the ends of the bones tend to snap off more often than not in those actions. That’s why we were finding these fragmentary bones.”
In the process of their research, the team discovered through diagnostic cranial material that these baby prey are a new, as yet-to-be-named dinosaur species. Details on this new species will soon be published in another paper.
Feeding Limbs and Nervous System of One of Earth’s Earliest Animals Discovered
Feb. 27, 2013 — An extraordinary find allowing scientists to see through the head of the ‘fuxianhuiid’ arthropod has revealed one of the earliest evolutionary examples of limbs used for feeding, along with the oldest nervous system to stretch beyond the head in fossil record.
Until now, all fossils found of this extremely early soft-bodied animal featured heads covered by a wide shell or ‘carapace’, obscuring underlying contents from detailed study.
But a new fossil-rich site in South China has been found to contain arthropod examples where the carapace has literally been ‘flipped’ over before fossilisation — allowing scientists to examine the fuxianhuiid head to an unprecedented extent.
The study, published today in Nature, highlights the discovery of previously controversial limbs under the head, used to shovel sediment into the mouth as the fuxianhuiid crawled across the seabed, millions of years before creatures emerged from the oceans.
Scientists say that this could be the earliest and simplest example of manipulative limbs used for feeding purposes, hinting at the adaptive ability that made arthropods so successful and abundant — evolving into the insects, spiders and crustaceans we know today.
Using a feeding technique scientist’s call ‘detritus sweep-feeding’, fuxianhuiids developed the limbs to push seafloor sediment into the mouth in order to filter it for organic matter — such as traces of decomposed seaweed — which constituted the creatures’ food.
Fossils also revealed the oldest nervous system on record that is ‘post-cephalic’ — or beyond the head — consisting of only a single stark string in what was a very basic form of early life compared to today.
“Since biologists rely heavily on organisation of head appendages to classify arthropod groups, such as insects and spiders, our study provides a crucial reference point for reconstructing the evolutionary history and relationships of the most diverse and abundant animals on Earth,” said Javier Ortega-Hernández, from Cambridge’s Department of Earth Sciences, who produced the research with Dr Nicholas Butterfield and colleagues from Yunnan University in Kunming, South China. “This is as early as we can currently see into arthropod limb development.”
Fuxianhuiids existed around 520 million years ago, roughly 50 million years before primordial land animals crawled from the sea, and would have been one of the first examples of complex animal life — likely to have evolved from creatures resembling worms with legs. Arthropods were the first jointed animals, enabling them to crawl.
Fuxianhuiid arthropods would have spent most of their time grazing on the sea floor, using these newly discovered limbs to plow sediment into their mouths. They could probably also use their bodies to swim for short distances, like tadpole shrimps.
The fossils date from the early part of the event known as the ‘Cambrian explosion’, when life on Earth went from multi-cellular organisms we know very little about to a relatively sudden and wide spread explosion of diverse marine animals — the first recognisable evolutionary step for the animal kingdom we know today.
“These fossils are our best window to see the most primitive state of animals as we know them — including us,” said Ortega-Hernández. “Before that there is no clear indication in the fossil record of whether something was an animal or a plant — but we are still filling in the details, of which this is an important one.”
While still a mystery, theories about the cause of the ‘Cambrian Explosion’ include possible correlations with oxygen rises, spikes in oceanic nutrient concentration, and genetic complexity reaching critical mass.
But the new site in South China where these fossils were found could prove to be key in uncovering ever more information about this pivotal period in the history of life on Earth. The Xiaoshiba ‘biota’ — that is the collection of all organisms preserved in the new locality — in China’s Yunnan Province is similar to the world-famous Chengjiang biota, which provided many of the best arthropod fossil records to date.
“The Xiaoshiba biota is amazingly rich in such extraordinary fossils of early organisms,” said Ortega-Hernández. “Over 50 specimens of fuxianhuiids have been found in just over a year, whereas previous areas considered fossil rich such as Chengjiang it took years — even decades — to build up such a collection.”
“So much material is so well preserved. There’s massive potential for Xiaoshiba to become a huge deal for new discoveries in early animal evolution.”
Evolution and the Ice Age
Feb. 26, 2013 — Dr John Stewart has made important contributions to a growing body of work that shows how the evolution of ecosystems has to be taken into account when speculating between different geological eras. Go back to the time of the dinosaurs or to the single-celled organisms at the origins of life, and it is obvious that ecosystems existing more than 65 million years ago and around four billion years ago cannot be simply surmised from those of today.
Although the most drastic evolutionary changes occur over long spans of time, the effects can be seen relatively recently, argues Dr Stewart.
Stewart has studied the interaction between ancient ecosystems — paleoecology — and evolution of humans and other organisms over the past 100,000 years, undertaking everything from excavating cave sites in Belgium to exploring the desert of Abu Dhabi.
In one milestone collaborative study, Dr Stewart has taken existing knowledge of the geographical spread of plant and animal species throughout the warming and cooling of the Ice Ages to provide insights into human origins, including the evolution and extinction of Neanderthals.
He has also examined the rise of the ‘first Europeans’, along with the Denisovans — a newly discovered group — mysterious cousins of the Neanderthals, who occupied a vast realm stretching from the chill expanse of Siberia to the tropical forests of Indonesia.
The key insight in this work, conducted alongside Prof Chris Stringer of London’s Natural History Museum, came from understanding the important role of the refuge taken by a species from harsher conditions — known as a refugium — which has a tremendous influence on the evolutionary future of the species. Once the climate changes again, for instance as ice sheets melt, these refuges can expand or connect up again.
But, of course, there’s a twist. Evolution has also had a huge influence. The inhabitants are not the same as the original populations as a result of genetic mutations. The time spent apart in refuge generally serves to splinter a once unified species.
Previous research into hedgehogs, polar bears and other animals suggest that, even once an Ice Age ends and the different populations start intermingling again, they never really merge back together as a single group. This process drives important evolutionary changes, which can ultimately lead to the origins of a new species.
Ultimately, this explains why Homo sapiens are still here and our archaic human cousins went extinct some 30,000 years ago: our ancestors chose the right refuge to wait out the Ice Age.
Today, Dr Stewart’s work has shifted away from fossil remains to ancient DNA. Traditionally insights into the evolution of species have come from fossils, but we now know that the genetic changes that underlie a major change in body shape can be minor.
“The most exciting development in my field has been the ability to analyse ancient DNA, which has begun to allow us to see evolution happening over the last several dozen thousand years,” explains Dr Stewart.
His claim that climate change caused the Neanderthals’ demise is supported by work by Love Dalén at the Swedish Museum of Natural History in Stockholm, who has looked at the genes in 13 Neanderthal fossils found in southern Europe and western Asia.
All Neanderthal fossils more than 48,000 years old, and those found in Asia, had a higher level of genetic diversity than later European fossils, suggesting that the Neanderthals probably went through an evolutionary ‘bottleneck’ where a significant percentage of them perished.
When a bottleneck occurs, the remaining individuals are often a much less diverse group, which makes it more difficult for them to evolve and adapt to a changing environment.
Dr Stewart, who is doing DNA studies in collaboration with teams at the Natural History Museum in Stockholm and the Universities of York and Royal Holloway, is now focusing on using genetics to elucidate the evolution of a wide range of creatures.
He has conducted recent studies at the cave site of Trou Al’Wesse, a refugium once occupied by Neanderthals, in Belgium. He is studying how animal populations changed as a result of Ice Age climate change to understand the evolutionary processes that have taken place over the last 50,000 years.
But his work is not confined to the past. It informs the present too. Recently there had been a proposal to eradicate the Eagle Owl because it killed other birds, such as hen harriers, and was not thought to be a native species. But Dr Stewart’s studies of fossils and more recent archaeological records revealed the bird, or something like it, has been present in Britain for up to 700,000 years. The plan to cull the birds has now been abandoned.
And his research can help us predict the future. The fear is that our ever-expanding impact on the planet will trigger ecological collapse. But the only way to know for sure is to look back into the past.
“By studying how organisms have reacted to past climate change,” explains Dr Stewart, “we can learn lessons about what may take place due to human-caused global warming.”