Meet your distant relative, Entelognathus primordialis, possibly the first earthling with a face. Or at least a familiar face.

Entelognathus primordialis (where Entelognathus means “complete jaw”) is described this week in Nature. Discovered in a quarry in China, the remarkably well-preserved fossil is somewhat 3D, displaying a modern type of jaw.

E. primordialis is a placoderm, an early class of fish that lived 430 to 360 million years ago. These fish were covered with an armor of bony plates and gave rise to two later groups—bony fish and cartilaginous fish.

The evolution of jaws is one of the key episodes in the evolution of vertebrates, but the gap between jawed and jawless vertebrates is so large that it has been hard to work out the individual evolutionary steps in the transition. Min Zhu and his colleagues hope to make the link with E. primordialis.

The 419 million-year-old fish fossil has jawbone features previously restricted to bony fishes, but has the full body armor seen in placoderms. It would have been around 20 centimeters (eight inches) long.

Prior to this recent find, most scientists agreed that placoderms had no jaw and were more similar to the cartilaginous fish, like modern day sharks, while the bony fishes are believed to be our ancestors. According to Nature News:

Such fishes went on to dominate the seas and ultimately gave rise to land vertebrates.

In addition to facing off with placoderms, the new study puts cartilaginous fishes into a whole new light—perhaps they are even more evolved than previously thought.

With their short wings relative to body size, hummingbirds are built for hovering. Their relatives, swifts, have super-long wings, built for gliding and high-speed flight. Their common ancestor, Eocypselus rowei, had wings sized between the two and they were built for… well, it’s hard to say.

“[Based on its wing shape] it probably wasn’t a hoverer like a hummingbird, and it probably wasn’t as efficient at fast flight as a swift,” says Daniel Ksepka of the National Evolutionary Synthesis Center.

Ksepka and his colleagues discovered a fossil of E. rowei in southwestern Wyoming at a fossil site known as the Green River Formation. The small bird—only twelve centimeters from head to tail—lived about 50 million years ago. Feathers account for more than half of the bird’s total wing length.

The researchers compared the specimen to extinct and modern day species. Their analyses suggest that the bird was an evolutionary precursor to the group that includes today’s swifts and hummingbirds. “This fossil bird represents the closest we’ve gotten to the point where swifts and hummingbirds went their separate ways,” says Ksepka.

Their study was published last week in the Proceedings of the Royal Society B.

The shape of the E. rowei’s wings, coupled with its tiny size, suggest that the ancestors of today’s swifts and hummingbirds got small before each group’s unique flight behavior came to be. “Hummingbirds came from small-bodied ancestors, but the ability to hover didn’t come to be until later,” Ksepka explains.

Closer study of the feathers under a scanning electron microscope revealed that carbon residues in the fossils—once thought to be traces of bacteria that fed on feathers—are fossilized melanosomes, tiny cell structures containing melanin pigments that give birds and other animals their color. The findings suggest that the ancient bird was probably black and may have had a glossy or iridescent sheen, like swifts living today. Based on its beak shape it probably ate insects, the researchers say.

Hummingbirds and swifts are two of many animals built for speed. Later this week, the Academy will open a new exhibit called Built for Speed, that will feature fast fishes and marine mammals. Learn more here.

Image: Mdf/Wikipedia

With six research papers in the current issue of Science, and numerous articles and blog posts surrounding those papers, Australopithecus sediba is the hominin du jour.

The papers reveal different anatomical features of Au. sediba and discuss their similarities to, and differences from, early human features. One news article calls them a “hodgepodge,” while another describes them as a “mosaic.”

“Amalgam” is how Zeray Alemseged, the Academy’s curator of anthropology, describes Au. sediba’s combination of human-like and more primitive features. Take the species’ heel. You and I walk by putting our broad and robust heel down and rolling to our toes, but Au. sediba’s heel was so narrow, these hominins couldn’t land on their heel, and likely walked on the sides of their feet and then pronated.

Similarly, Au. sediba’s torso had a conical and quite primitive shape, and their shoulders were “shrugged.” Alemseged explains, “With short necks and a narrow clavicle, they appeared to be ape-like with a substantial adaptation for climbing.”

However, the lower ribs were slightly human-like and the teeth were a mixture “of primitive and human traits,” according to an accompanying article in Science.

The findings are based on fossils found in South Africa by Lee Berger’s team in 2008, and include three skeletons.  The recent studies pinpoint Au. sediba’s existence to around 1.98 million years ago and make a few proposals on how to place the species in our lineage. In fact, Berger suggests that Au. sediba could be the direct ancestor to our genus, Homo.

“Lee is a good colleague, but I happen to disagree with him about that,” Alemseged says. “It’s a fascinating discovery and the quality of preservation of the fossils and number of skeletons are great,” but Alemseged sees no evidence that Homo descended from Au. sediba. “The fossil record indicates that by 2.33 million years ago, Homo already exists,” predating Au. sediba, Alemseged explains.

In addition, the findings (especially in regards to the dental study) suggest that Au. sediba was closely related to Australopithecus africanus, but not Australopithecus afarensis, the species Alemseged studies. He finds the evidence linking Au. sediba and Au. africanus solid, but that doesn’t leave Au. afarensis out. Given the timing, Au. afarensis, which lived between 3.8 and 2.9 million years ago, was likely the ancestor of Au. africanus, which lived between 3.3 and 2.1 million years ago and in turn was the ancestor of Au. sediba.

Alemseged notes that the studies underscore the diversity of our lineage. “It’s not surprising, in the natural world, to find multiple species of any given group,” so why should our family tree be any different?

Despite his scientific disagreement with his colleague, Alemseged lauds Berger’s generous sharing of the fossils and studies related to Au. sediba. “He’s introduced a new culture in paleontology of being very open.”

Finally, the image accompanying many of the articles (above right) is very similar to an animation comparing Au. afarensis, humans and chimpanzees in the Academy’s current exhibit, Human Odyssey that Alemseged curated. If you haven’t visited it yet, it explores Australopithecus, Homo, and more!

Image: Lee R. Berger And The University of the Witwatersrand

The fossils date from 542 to 635 million years ago and, since their discovery in 1947, have been described as marine fossils. Now, a researcher at the University of Oregon believes new evidence prove the fossils to be terrestrial—making them the first terrestrial fossils ever. If true, it would mean that life on land evolved 10 to 100 million years earlier than previously thought.

But the caveat “if true” is quite a big question. Could they possibly be terrestrial? I spoke to the Academy’s Peter Roopnarine about this latest hypothesis, published last month in Nature.

“The fossils in question date to the Vendian and earliest Paleozoic—just before and in the earliest days of the animal fossil record that begins with the Cambrian Explosion,” Roopnarine explains. “The fossils are usually referred to as the Ediacaran Fauna, based on the region of their first discovery in Australia. But they have since been found all over the world.

“They are extremely important because they give us our first material evidence of complex life forms on Earth, either many-celled colonies of eukaryotic organisms or true multicellular organisms,” he adds. “They are evidence that the world was changing dramatically, and really set the stage for the next big leap, the Cambrian Explosion.”

Given this description of these fossils, it’s easy to understand why the newly proposed definition—from marine species to terrestrial species—is a big deal. In addition, the author of this new study, Greg Retellack, has been making this claim for years. The latest study is just further evidence for this claim, according to Retellack.

Using chemical and microscopic techniques, Retellack studied numerous Ediacaran fossils and claims that the diversity reflects a preference by the ancient organisms for “unfrozen, low salinity soils, rich in nutrients, like most terrestrial organisms.” In other words, the soils that these organisms inhabited were terrestrial, not underwater. His study determines that instead of ancient marine creatures, these fossils could have been lichens, microbes, fungus or slime molds.

Roopnarine disagrees. “I don’t lend much credence to the hypothesis. As indicated in a Nature News piece, there is very little sedimentological evidence to support Retallack’s claim. He sees fossil soils, but every other independent study concludes that the sediments are marine. I also do not buy the lichen or slime-mold ideas. The fossils show a great deal of organization of the bodies. They are recognizable as particular species wherever you find them. At best I would say we’re seeing a highly organized fungus, but a more likely explanation is a combination of early animal body-plans and maybe some other branch of the multi-cellular eukaryotic tree of life that subsequently went extinct.”

Nonetheless, Roopnarine isn’t surprised at the lasting debate over the fossils. “Arguments and competing hypotheses can last for decades, sometimes a century or more in science,” he explains. But, for him, weighing the evidence clearly sides with these Ediacaran fauna as marine species. “Because the Ediacaran fauna is so unlike anything else that we know, we will never truly be able to settle this and say exactly what they were. But we can at least say what is consistent with the data that we do have, and the data here do not support a terrestrial setting, nor, in my opinion, a fauna of terrestrial lichens.”

Image: Greg Retallack

Catching glimpses into our fossil ancestors’ daily lives is a tricky business. Fossil remains of our ancestors can only tell us so much concrete information, and tracing our DNA backwards in time can only get us so far.

But bones and teeth hold more clues than you’d think, if you just know how to extract them. In a new research paper published in the journal Nature, evolutionary anthropologists harnessed cutting-edge chemical tools and analyses to uncover the social patterns of our earliest ancestors and in so doing, discovered that males weren’t too keen on leaving their childhood homes.

The study, led by Sandi Copeland of the Max Planck Institute for Evolutionary Anthropology, looked at fossilized teeth from South Africa: eight Australopithecus africanus (2.2 million years ago) individuals and 11 individuals belonging to the Paranthropus robustus (1.8 million years ago) species. Using a laser, the team extracted a key element from the tooth enamel called strontium.

The strontium found in tooth enamel is like a snapshot into where the person lived during childhood, when permanent teeth developed. The various types of strontium, called isotopes, can be connected with specific geographical regions. “The strontium isotope ratios are a direct reflection of the foods these hominids ate, which in turn are a reflection of the local geology,” Copeland explains.

The research team divided sets of teeth for both species into male and female based on size (male teeth are generally larger). They then performed strontium isotope analysis on each, looking for clues into the each specimen’s childhood geographical landscape. They found that a large majority of male specimens – nearly 90% – grew up in the same general area where the fossilized teeth were uncovered. They were born, grew up, and died in pretty much the same place: the prehistoric equivalent of their hometown.

But analysis of female strontium isotopes revealed a different history. Over 50% of female remains trace to further afield, away from the dolomite cave systems that so many males grew up near. It seems that many females spent their formative years elsewhere, only arriving in the area once they reached adulthood.

Chimpanzees, our closest living primate relatives, exhibit a similar social structure. Male chimps are highly territorial, and will not leave their home base, even upon reaching adulthood. To prevent inbreeding, females are often forced to leave their childhood groups in search of new mating partners in other groups. Copeland’s strontium-isotope analysis lends support to the idea that early hominids might have done the same. If this structure exists in both chimpanzees and early hominids, perhaps its origins extend much further back in time.

“One of our goals was to try to find out something about early hominin landscape use. Here we have the first direct glimpse into the geographic movements of early hominids,” says Copeland.

The study not only provides insight into previously unknown aspects of ancient hominin social structure, it also highlights exactly how much new information can be squeezed out of a fossil specimen. As Julia Lee-Thorp, one of the study’s co-authors, explains, “Studies like these really bring home that finding and describing fossils is not the end of the story. Thoughtful application of these new analytical methods can tell us such a lot more about the details and lives of the distant past.”

Anne Holden, a docent at the California Academy of Sciences, is a PhD trained genetic anthropologist and science writer living in San Francisco.

Image: Darryl de Ruiter

Exciting announcements about human evolution have captured our attention recently. First, we added a new branch to our family tree with Ardipithecus ramidus, or “Ardi.” Then we learned our earliest primate ancestors may have evolved not in Africa (contrary to conventional wisdom) but in Asia.  And now, fossil remains from China seem to radically change what we thought we knew about our species’ arrival in East Asia. It’s been a busy year for human evolution, and the year’s not over yet.

In the most recent discovery, published last week in the Proceedings of the National Academy of Sciences, an international team of experts described three fossils: two teeth and part of a jaw. The remains were found in Zhiren Cave in southern China. They date back 100,000 years, and the authors say the fossils are of human origin.

This discovery has ruffled a few feathers among the experts. Why? Because conventional wisdom places the arrival of humans into East Asia just 50,000 years ago. The remains from Zhiren Cave are twice as old.

Both fossil and genetic evidence place the origin of humans in Africa about 150,000 years ago. According to conventional widsom, humans didn’t make the long trek to Asia for another 100,000 years. Once they got there, most experts agree, they pushed out or replaced the groups of earlier ancestors, like Homo erectus, who had been living there for over a million years.

The discovery of these fossils may change that timeline. Erik Trinkaus from Washington University in St. Louis (and one of the paper’s authors) noted, “These fossils are helping to redefine our perceptions of modern human emergence in eastern Eurasia, and across the Old World.”

What makes these fossils so interesting isn’t just their age, the authors say. It’s the fact that they have a mix of human and archaic (you might say “pre-human”) features. The chin especially is decidedly human (our earlier ancestors were chin-impaired), while other features seem much more primitive. Are these remains the result of humans and Homo erectus “intermingling”?

This discovery does not come without its critics, however. John Hawks from the University of Wisconsin questions whether the presence of a chin alongside archaic features is a convincing enough argument. With so few remains, he says, we need to know how genes build the jaw in the first place before we can understand how these remains fit into the twigs and branches of our family tree.

Anne Holden, a docent at the California Academy of Sciences, is a PhD trained genetic anthropologist and science writer living in San Francisco.

According to an article published this week in the journal Nature, Concaveator corcovatus was a shark-toothed predator and, per a supporting article,

… about 4 metres long [13 feet] from nose to tail and lived during the Early Cretaceous period, about 130 million years ago.

Its name literally means “the hunchback hunter from Cuenca,” describing both the location where it was found in central Spain and one of its most unique features. Again, from Nature:

Its eleventh and twelfth vertebrae jut about twice as far from the animal’s body as the rest. Unlike dinosaurs such as Spinosaurus, which had continuous fins or sails on their backs, Corcovenator seems to have had more of a short crest.

Researchers remain uncertain about the reason for this humpbackedness—perhaps it provided a showy display, stored energy or kept the creature cool. As Ed Yong says in his “Not Exactly Rocket Science” blog for Discover,

… sometimes, these [dinosaur] body parts are so bizarre that their purpose is a mystery.

Even though Concavenator’s humpback is super cool, that’s not the reason its discovery has received so much attention. Because the fossil was so well preserved, another exciting trait came to light. From ScienceNews:

Concavenator also has bumps on its forearm bones that look a lot like quill knobs seen on the wing bones of modern birds. Quill knobs are attachment points in the bone for ligaments that support a bird’s flight feathers. This could mean that Concavenator had featherlike structures on its arms.

If other researchers can confirm this finding, it would push back the existence of feathered dinosaurs to much earlier than previously thought.

No wonder all the fuss, funny name or not.

Image above: Raúl Martín

(Some great images of the fossils can be found here.)

The 318 million-year-old reptile footprints were found in sea cliffs on the Bay of Fundy, New Brunswick, Canada. They show that reptiles were the first vertebrates to conquer dry continental interiors. These pioneers paved the way for the diverse ecosystems that exist on land today.

The footprints were discovered by Dr. Howard Falcon-Lang of Royal Holloway, University of London. According to New Scientist,

Around five centimeters long, the five-toed prints were made by small gecko-like creatures. “I discovered them by accident when I tripped over [them],” Falcon-Lang says.

Hundreds of stunning footprints belonging to at least three different kinds of reptile have been preserved at the site, all in sediments that, at the time the prints were made, were more than 500 kilometers [over 300 miles] inland within the supercontinent Pangaea.

The results of this study are published in the journal Palaeogeography, Palaeoclimatology, Palaeoecology.

New Scientist also reports that “amphibians were the first creatures to make it onto land, hopping up the beach somewhere between 400 and 360 million years ago.” But, it has long been suspected that reptiles were the first to colonize continental interiors since they don’t need aquatic habitats to breed, unlike their amphibian cousins. The new footprint discovery bolsters this theory.

It may have been one small step for reptile-kind, but it was one giant leap for vertebrate diversity.

Image: University of Bristol

In attempting to discover how pre-historic, 300 million year old cockroaches lived and behaved, a team of scientists in London have modeled a fossilized specimen of Archimylacris eggintoni, and published their research in the journal Biology Letters.

Archimylacris eggintoni is an ancient ancestor of modern cockroaches, mantises and termites. This insect scuttled around on Earth during the Carboniferous period 359 — 299 million years ago, which was a time when life had recently emerged from the oceans to live on land.

The study reveals for the first time how Archimylacris eggintoni‘s physical traits helped it to thrive on the floor of Earth’s early forests. The fossils of these creatures are normally between 2cm and 9cm in length and approximately 4cm in width.

“Thanks to our 3D modelling process, we can see how Archimylacris eggintoni‘s limbs were well adapted for all terrains, as it was not only adept in the air but also very agile on the ground,” according to Russell Garwood, a PhD student from the Department of Earth Science and Engineering at Imperial College London and the lead author of the study.

Using a CT scanning device, the researchers were able to take 3,142 x-rays of the fossil and compile the images into an accurate 3D model, creating a ‘virtual fossil’ of the creature.

Because very few limbs of this species—or other roach-like insects from this era—have been preserved in fossils, it has been hard for scientists to glean insights into their way of life. But the new model suggests that Archimylacris eggintoni‘s legs could help it to run fast.

They were able to gleam more information, as well. Garwood adds: “We now think this ancient ancestor of the cockroach spent most of the day on the forest floor, living in and eating lots of rotting plant and insect matter, which was probably the bug equivalent of heaven. We think it could have used its speed to evade predators and its climbing abilities to scale trees and lay eggs on leaves, much in the same way that modern forest cockroaches do today.”

Image Credit: Imperial College London and the Natural History Museum

Found several years ago in Ethiopia, a large team of interdisciplinary scientists (including paleontologists, geologists and microbiologists) studied the amber for the past five years. It dates back 95 million years to the Cretaceous period.

It is known that dinosaurs roamed Africa during that period, but the fossils found inside the amber displayed many more diverse forms of life. The amber held fossilized ants and other insects, spiders, ferns, fungi and even bacteria. The ant finding is significant because it is one of the oldest ant fossils found and could reveal more about ant evolution. Until now, paleontologists thought ants originated in North America or South Asia (the oldest fossils had been found there), but it now seems that Africa could have been their starting point.

In addition, the amber deposit may provide fresh insights into the rise of flowering plants during the Cretaceous. “The first flowering plants appeared and diversified in the Cretaceous,” says lead author Alexander Schmidt of the University of Göttingen in Germany. “Their rise to dominance drastically changed terrestrial ecosystems, and the Ethiopian amber deposit sheds light on this time of change.”

Amber is fossilized tree resin that sometimes contains animals and plant material. The researchers do not know from which tree this amber originated. According to author Paul Nascimbene, of the Division of Invertebrate Zoology at the American Museum of Natural History, “This amber could be from an early flowering plant or a previously-unknown conifer that is quite distinct…”

Amber from the Cretaceous period is primarily found in North America and Eurasia.  This Ethiopian amber is the first major discovery of its kind from the African continent.  And the diversity of life discovered in this deposit promises to reveal new information about Africa’s evolutionary past.

Image courtesy of PNAS/ Matthias Svojtka