Extinct horse with fossil uterus discovery

A skeleton of a Eurohippus messelensis mare is shown with its fetus (white ellipse). (photo: Sven Traenkner)

From the Los Angeles Times in the USA:

Oldest preserved uterus found in ancient horse-like fossil

Deborah Netburn

October 7, 2015

Talk about a mother of a discovery: Researchers in Germany have found the fossil of a 48-million-year-old pregnant horse relative, her fetus and bits of her preserved uterus as well.

It is the oldest and only the second fossil uterus ever described, according to Jens Franzen of the Senckenberg Research Institute in Frankfurt, Germany.

Franzen and his colleagues described the find in a paper published Wednesday in PLOS One.

Less than 2% of fossil mammal finds have yielded anything more than fragments of jaw material and other bones, which makes this discovery particularly unexpected.

The primitive horse relative is known as Eurohippus messelensis. It was much smaller than modern-day horses. Even fully grown, the ancient equine was about the size of a fox terrier — about 12 inches high at the shoulders. It was discovered in Grube Messel, near Darmstadt, Germany.

In the picture above, you are looking mostly at the fossilized remains of the mare. The fetus is located in the white oval.

Franzen and his colleagues report that the 48-million-year-old uterus looks nearly identical to those found in modern horses. This suggests that the uteral system was already well developed by the Eocene period (56 to 34 million years ago), and may date back to the Paleocene era (66 million to 56 million years ago) or even earlier.

Grube Messel is a former shale quarry that is famous for its complete vertebrate skeletons. Back in the time when Eurohippus messelensis roamed, it was a freshwater lake, surrounded by a tropical rainforest.

Animals that fell in the lake were preserved thanks to an interaction between bacteria in the lake and iron in the water.

After a dead animal was submerged in the lake, bacteria gathered on its soft tissue and started producing CO2. The CO2 reacted with the iron in the lake to form iron carbonate minerals. This material hardened on the bacteria, creating a fixed bacterial mat that exactly followed the lines of the decomposing soft tissue.

“The bacteria petrified themselves,” Franzen said.

The preserved bit of uterus was not immediately obvious, however. The researchers said they first noticed a “conspicuous gray shadow” between the fetus and the lumbar vertebrae of the mother, after taking a micro X-ray of the fossil.

They eliminated the possibility that the shadow was an artifact of preparation or an abdominal muscle. Eventually, they concluded that they were looking at the oldest bit of fossilized uterus ever seen.

The authors are still not sure what killed the mother Eurohippus messelensis, but it is unlikely that childbirth was to blame. Although the fetus was near term when its mother died, it was not yet positioned to enter the birth canal.

See also here. And here.

Extinct human Homo naledi’s hands and feet, new study

This video says about itself:

10 September 2015

Paleoanthropologist and explorer Lee Berger has made an important new discovery in the human family tree: a new species called Homo naledi. In this interview with journalist Bill Blakemore, Berger gives the details of the find, how it came about, the difficulty in recovering the fossils, and why it’s such an important find.

From Nature Communications:

The foot of Homo naledi

6 October 2015


Modern humans are characterized by a highly specialized foot that reflects our obligate bipedalism. Our understanding of hominin foot evolution is, although, hindered by a paucity of well-associated remains.

Here we describe the foot of Homo naledi from Dinaledi Chamber, South Africa, using 107 pedal elements, including one nearly-complete adult foot. The H. naledi foot is predominantly modern human-like in morphology and inferred function, with an adducted hallux, an elongated tarsus, and derived ankle and calcaneocuboid joints. In combination, these features indicate a foot well adapted for striding bipedalism.

However, the H. naledi foot differs from modern humans in having more curved proximal pedal phalanges, and features suggestive of a reduced medial longitudinal arch. Within the context of primitive features found elsewhere in the skeleton, these findings suggest a unique locomotor repertoire for H. naledi, thus providing further evidence of locomotor diversity within both the hominin clade and the genus Homo.

Also from Nature Communications:

The hand of Homo naledi

6 October 2015


A nearly complete right hand of an adult hominin was recovered from the Rising Star cave system, South Africa. Based on associated hominin material, the bones of this hand are attributed to Homo naledi.

This hand reveals a long, robust thumb and derived wrist morphology that is shared with Neandertals and modern humans, and considered adaptive for intensified manual manipulation.

However, the finger bones are longer and more curved than in most australopiths, indicating frequent use of the hand during life for strong grasping during locomotor climbing and suspension. These markedly curved digits in combination with an otherwise human-like wrist and palm indicate a significant degree of climbing, despite the derived nature of many aspects of the hand and other regions of the postcranial skeleton in H. naledi.

Sharks, 450 million years ago till today

This 2014 video says about itself:

Wherein we take an adventure into the deep oceans of history in pursuit of fossilized sharks.

From the BBC:

The epic history of sharks

There are many strange sharks but their ancestors were even weirder and more wonderful than those swimming today

By Lucy Jones

3 October 2015

When you imagine a shark, you may think of a torpedo-shaped, streamlined creature with a prominent dorsal fin, a large mouth ringed by sharp, triangular teeth and a crescent-shaped tail. Jaws, basically.

Actually, the shark group of fish are widely varied. The Epaulette shark (Hemiscyllium ocellatum) can walk on land, the frilled shark (Chlamydoselachus anguineus) is flatter-bellied, adapted to hunt in the deep-sea, the tasselled wobbegong (Eurcrossorhinus dasypogon) is a carpet shark that resembles an old patterned rug and the goblin shark (Mitsukurina owstoni) is eel-like with a long dagger-shaped snout.

These are just a handful of over 500 species of shark that we know about today, each well-adapted to its particular environment.

Yet in the past, there were many more: fossil records suggest more than 3,000 types of shark and their relatives existed at one time. And some of the ancestors of modern sharks were even weirder and more wonderful than those swimming today.

Their long history starts in the late Silurian period, about 450 million years ago. It was a time when sea levels were high and coral reefs began to form. The Earth’s climate was warm and stable. Molluscs, crinoids and trilobites were some of the only living creatures on the Earth before scorpions and centipedes appeared on the land.

Around this time, sharks too appeared, evidenced by the oldest known shark scales found in Siberian deposits.

Jawed and bony fish began to diversify, including the evolution of a group of fish called acanthodians, or “spiny sharks”. These extinct fish looked like small sharks but had varying numbers of fins.

“It appears that sharks arose from within those,” says Charlie Underwood of Birkbeck University of London, UK. “Where they end and sharks begin is quite up for debate. Certainly we know that some of these acanthodians have teeth that formed in a very similar way to sharks. The teeth will grow on the inside of the mouth and move forward as they get bigger, in a sort of conveyor belt. Among these are the earliest sharks.”

Fast forward 50 million years to the Early Devonian, a warm and arid time on Earth when forests spread across the land, seed-bearing plants first appeared and the planet underwent great geological change.

This is when we have the first remains of shark teeth, from the Leonodus shark. These teeth are both small (4mm) and two-pronged, but they offer few clues as to what the Leonodus shark actually looked like. They are similar to the teeth of another shark called Xenacanthus that appeared millions of years later in the Late Devonian, leading to speculation that Leonodus, like Xenacanthus, lived in freshwater.

It may seem that teeth are not much to go by, but everything we think we know about shark evolution is from the teeth, says Lisa Whitenack of Allegheny College in Pennsylvania, US. From teeth, she says, we can learn about what environment the shark lived in, what they ate and how they are related to other sharks.

But we have to wait until 380 million years ago for the next clue to shark evolution. That comes from the braincase of Antarctilamna, a so-called lamnid shark from Antarctica. Its head, fin, spines and teeth suggest that it was eel-like.

There’s a reason the Devonian period is referred to as the ‘Age of Fishes‘. It was the time when they diversified greatly. A skeleton of the now extinct shark Cladoselache, shows just how much. It was very different from its eel-like ancestors. It was a 2m-long, torpedo-shaped shark with equal-sized dorsal fins, a short stout spine in the front, five fill slits and large eyes. It took its prey tail-first, indicating it could easily outswim its meals.

At this time, a school-bus sized group of fish called Dunkleosteus, also swam the seas. These were giant, heavily-armoured fish and may have competed for similar prey. This could have been just the trigger sharks needed to evolve further. Other armour-plated fish existed too, but it was early sharks that seemed to have something that allowed them to thrive, while these other giants died out.

Enter the golden age of sharks, 360 million years ago during the Carboniferous period. The largest predators of the sea at this time were the Chondrichthyans (cartilage fish). They had their skeletal jaws and tough scaly skin to thank for that. The enamel on their teeth was also frequently replaced.

This group included rays (close relatives of sharks), skates and a bizarre branch called the chimaeras, which featured species such as ratfish, ghost sharks and spook fish. It was within this last group, the chimaeras, that extremely weird and wonderful sharks appeared, says Underwood. “By the Carboniferous period, the majority of shark-like things are on the chimaeras branch, rather than the branch towards modern sharks.”

Prehistoric sharks certainly looked much stranger than the modern sharks we share the planet with today, even weirder than the Port Jackson, with its strange patterning and smoothed, numerous fins.

This video is called Port Jackson Sharks (Heterodontus portusjacksoni ), 4 young sharks chilling out on the sand, Sydney, Australia.

The Stethacanthus, for example, had an anvil-shaped dorsal fin on its back. “No one really knows what it used it for,” says Christopher Bird, of the National Oceanography Centre, Southampton, UK and Shark Devocean blog. It is one of many evolutionary mysteries in the shark world.

Another was the spiral-shaped tooth structure, called a tooth whorl, of the Helicoprion. These were dinner-plate sized and likely sat at the tip of the lower jaw. Some of these tooth spirals were 40cm across.

“As they grow and move into the mouth position, rather than falling out, the teeth just stay stuck to each other,” explains Underwood. “The shark doesn’t lose teeth as they move outside the mouth. So you end up with the bottom lower jaw having a big circular blade sticking out and behind that… crushing teeth. It’s a very strange arrangement.”

These bizarre traits aside, ancient sharks actually had the same basic features as the sharks we know today.

More innovation occurred at the start of the Jurassic period, 213 million years ago, when 12 new groups evolved. Sharks with flexible jaws started to appear. This meant they could feed on things that were bigger than themselves, says Bird. “They were able to exploit the newly emerging habitats as the world was changing.”

Their protruding jaws came to good use. They could eat, crunch or suck prey into their mouths. “Sharks in the Jurassic period often had teeth with a flat-ridged surface to make it easier to crunch on crunchy things,” says Whitenack.

As environments changed, sharks evolved different features. A tail fin allowed sharks to swim faster for long distances to pursue prey. Most sharks evolved a mouth under their snout, although a few species have mouths at the front of their snouts such as the frilled shark and angel shark.

Sharks were certainly tenacious. The creatures that thrived during this period survived right into the Cretaceous, often defined by its end. Sixty-five million years ago most of the dinosaurs were wiped out. Many other animals died too but sharks lived on.

And why wouldn’t they? They had already survived four other catastrophic mass extinctions. Their bodies were clearly well adapted to survive.

What’s more, they could exploit the fact that so many other creatures were wiped out. It was during these “recovery stages following historic mass extinctions” that the biggest number of new species appeared, says Bird.

Following the asteroid that wiped out the dinosaurs, for example, there was a second wave of deep-sea sharks. “The sharks are able to recolonise the water. We start seeing the cookie-cutter sharks and lantern sharks move in after this post-crisis event,” says Bird.

These also exploited new habitats following extinction events. They even managed to survive during times when the ocean lost its oxygen – including one such event in the Cretaceous period, when many other, larger, species died out. As a refuge, sharks moved deeper underwater, says Bird. And while there, they had another cunning trick. Some evolved the ability to glow in the dark.

The end of the Cretaceous gave sharks the opportunity to flourish. Not all survivors were successful though, including one giant of the sea, once thought to be a direct relative of the great white shark.

About 16 million years ago the Carcharodon megalodon first appeared. It could grow up to 16.8m and weighed 25 tonnes. Its mouth would gape open an impressive 2m, showing its 15cm-long teeth, perfect for eating everything else big in the ocean. It made the great white shark look like a goldfish in comparison.

We don’t know why the megalodon went extinct. One idea is that climate change disrupted the availability of prey. It was big, so needed to eat a lot. Any tiny change could therefore have threatened its survival. It’s likely that many factors combined to cause this giant to disappear two million years ago.

Other survivors from the Cretaceous lived on to become the sharks we know today. Hammerhead sharks for example, are among the most recent to appear in the fossil record and are assumed to be one of the last modern shark orders to evolve.

Their t-shaped heads increase lift as the sharks swim through the water, allowing them to make sharp turns. It also helps them sense more of their environment.

And we now have greater insight into how their strange-shaped heads evolved. Genetic techniques allow us to peer back in time at the evolution of modern-day sharks. In one such experiment in 2010, scientists looked at the DNA of eight species of hammerhead to build a genetic family tree going back thousands, possibly even millions, of generations.

Our study indicates the big hammerheads probably evolved into smaller hammerheads, and that smaller hammerheads evolved independently twice,” said Andrew Martin of the University of Colorado at Boulder, at the time of the study.

“As the sharks became smaller, they may have begun investing more energy into reproductive activities instead of growth.”

Recently, it has become clear that we may not even know how many sharks live in the ocean. An elusive shark called the megamouth (Megachasma pelagios), was only discovered several decades ago. In 1976 a US research vessel off the coast of the Hawaiian island of Oahu hauled up a shark nearly 5m in length, with a great fleshy mouth surrounding broad jaws.

ince then, 49 have been found all over the world. Usually they are dead when caught but one living specimen has given scientists some idea of its environment and habits. Its soft cartilage and flabby tissue suggests a slow-steady swimmer that filter-feeds on shrimp, sea jellies and small crustaceans.

But despite new species still being discovered, the very survival of sharks is under threat. Many are endangered and their biggest threat? Us. Climate change, pollution and habitat destruction are all factors affecting their numbers.

The main threat to their survival is overfishing. Humans kill many species in large quantities for meat and fins. Several are now on a list that seeks to protect endangered species from international trade (the CITES list), and includes open-water predators such as basking, whale and great white sharks, which are caught in vast quantities for meat.

Even deep-sea sharks are vulnerable. Despite the incredible features they have evolved to help them succeed, their reproduction rate is slow. That means if any are killed, the knock-on effect is huge.

Deep-sea shark species can’t recover, explains Bird. They don’t have the potential to reproduce offspring quicker than they’re being taken out. These sharks are often targeted for their liver oil. It contains a molecule called squalene, sought after by the cosmetics industry for its moisturising properties.

The International Union for Conservation of Nature (IUCN) now estimates that a quarter of sharks and rays are threatened with extinction. Although sharks have survived several mass extinctions, the rate at which their populations are being reduced by human activity is extreme and many species are not protected. In 2014, scientists said improved management of fisheries and trade is “urgently needed” to promote population recovery.

If their rate of decline continues, the future of sharks is uncertain. “We’re a new predator in the ocean,” says Bird. Sharks were once top predator but “we’re decimating their populations. One day, they may not be able to bounce back and recover.”

Woolly mammoth discovery in Michigan, USA

This video from the USA says about itself:

Woolly mammoth skeleton unearthed by Michigan farmers

3 October 2015

Two farmers in Michigan made an astonishing discovery when they unearthed the remains of a woolly mammoth while digging in a soybean field.

Experts say it is one of the most complete sets ever found in the state.

University of Michigan researchers say there is evidence the mammoth lived 11,700-15,000 years ago.

Fossil bats’ colours revealed

This video says about itself:

12 August 2015

“”Palaeochiropteryx””­; is an extinct genus of bat from the Middle Eocene of Europe. It contains two very similar species – “”Palaeochiropteryx tupaiodon”” and “”Palaeochiropteryx spiegeli“”, both from the famous Messel Pit of Germany. They are usually found complete and exceptionally preserved, even retaining the outlines of their fur, ears, and wing membranes.

They are one of the oldest bats known, existing around 48 million years ago. Despite this, they were already quite advanced, showing evidence of the ability to hunt by echolocation like modern insect-eating bats.

“Palaeochiropteryx” were small bats … Their wings were short but broad, indicating an adaptation for slow but highly maneuverable flight beneath forest canopies and among dense vegetation. They preyed mostly on moths and caddisflies and were probably nocturnal.

Fossils of both species of “Palaeochiropteryx” were first recovered from the Messel Pit, near the village of Messel, Germany in 1917. They were described and named by the Swiss naturalist Pierre Revilliod. He placed them under their own family – Palaeochiropterygidae. The name “Palaeochiropteryx” means “Ancient hand-wing”, from Greek παλαιός, χείρ, and πτέρυξ.

The two species have only been found at Messel. They are quite common and account for three quarters of all bat fossils found there, with “Archaeonycteris”, “Hassianycteris”, and “Tachypteron” making up the rest. Like other fossils from the locality, they are often found in remarkable states of preservation.

From Reuters news agency:

Mon Sep 28, 2015 3:50pm EDT

Fossilized fur reveals color of 49-million-year-old bats

By Will Dunham

Fossils can do a good job of revealing key aspects of an extinct creature: its bones, teeth, claws, even soft tissue like fur, skin, feathers, organs and sometimes remains of its last meal in the gut. Knowing its color has been a trickier question.

But scientists have figured out how to answer it based on microscopic structures in fossils that divulge pigment, and on Monday disclosed for the first time the fur color of extinct mammals: two of the earliest-known bats.

The bats, called Palaeochiropteryx and Hassianycteris, were a reddish brown.

“Well, the bats are brown. It might not be a big surprise, but that’s what these 49-million-year-old bats are. So they looked perfectly like modern bats,” said molecular paleobiologist Jakob Vinther of Britain’s University of Bristol.

Vinther also has used the method to study colors in dinosaurs, fish, amphibians and fossil squid ink. The method was first described in 2008 regarding a 105-million-year-old black-and-white striped feather from Brazil and also showed that a winged dinosaur from China, Microraptor, boasted iridescent feathers.

“Biologists know a lot about living animals because of color: what sort of environment they live in, how they protect themselves or how they attract mates,” Virginia Tech paleobiologist Caitlin Colleary said.

“But since so little is preserved in the fossil record, the color of extinct animals has always been left up to artists’ interpretations, and important information regarding behavior has been considered inaccessible.”

The bats lived along a lake in the middle of a tropical forest in Germany. The scientists examined the beautifully preserved bat fossils that retained structures called melanosomes.

Melanosomes contain melanin, the pigment that gives color to skin, hair, feathers and eyes. They possess distinctive shapes that indicate pigment color.

“Reddish brown melanosomes are little tiny meatballs around 500 nanometers in diameter, while black melanosomes are elongated sausages about a micron in length,” Vinther said.

Skeptics had questioned whether the structures were bacterial remnants, not melanosomes. But Vinther’s team for the first time got chemical data on the fossils, determining the structures were not bacterial and that they contained melanin remnants.

“I think we’re just scratching the surface in our ability to extract information like this from the fossil record,” Colleary said. “As technology continues to advance, we’ll keep finding information in fossils that we don’t even know is there today.”

The research was published in the Proceedings of the National Academy of Sciences.

(Reporting by Will Dunham; Editing by Sandra Maler)

Hadrosaur dinosaur discovery in Alaska

This video from the USA says about itself:

Research Team Discovers ‘Lost World’ of Cold Weather Dinosaurs

22 September 2015

A collaborative team between Florida State University and the University of Alaska Fairbanks has spent the last five years digging in a remote bone-bed of dinosaur remains in the remote Prince Creek Formation in Alaska. FSU Professor Gregory Erickson is excited for the new species of duck-billed dinosaurs uncovered in the dig and believes it opens up a lost province of Arctic adapted dinosaurs. The new dino, Ugrunaaluk kuukpikensis, is closely related to Edmontosaurus, another duck-billed dinosaur found further south near Alberta, Montana, and South Dakota, but several structural differences in adult skeletons helped Erickson and Pat Druckenmiller of the University of Alaska Fairbanks determine it is in fact a different species.

From the University of Alaska Fairbanks:

22 September 2015

New hadrosaur species discovered on Alaska’s North Slope

Research team finds evidence for ‘lost world’ of cold weather dinosaurs

Researchers working with specimens at the University of Alaska Museum of the North have described a new species of hadrosaur, a type of duck-billed dinosaur that once roamed the North Slope of Alaska in herds, living in darkness for months at a time and probably experiencing snow. Ugrunaaluk (oo-GREW-na-luck) kuukpikensis (KOOK-pik-en-sis) grew up to 30 feet long and was a superb chewer with hundreds of individual teeth well-suited for eating coarse vegetation.

Earth sciences curator Pat Druckenmiller said the majority of the bones used in the study came from the Liscomb Bone Bed, a fossil-rich layer along the Colville River in the Prince Creek Formation, a unit of rock deposited on the Arctic flood plain about 69 million years ago.

“Today we find these animals in polar latitudes,” Druckenmiller said. “Amazingly, they lived even farther north during the Cretaceous Period. These were the northern-most dinosaurs to have lived during the Age of Dinosaurs. They were truly polar.”

The name, which means ancient grazer, was a collaborative effort between scientists and Iñupiaq speakers. Druckenmiller worked with Ronald Brower Sr., an instructor at the University of Alaska Fairbanks Alaska Native Language Center, to develop a culturally and geographically appropriate name that honors the native Iñupiaq people who live there today.

Druckenmiller; UAF graduate student Hirotsugu Mori, who completed his doctoral work on the species; and Florida State University’s Gregory Erickson, a researcher who specializes in the use of bone and tooth histology to interpret the paleobiology of dinosaurs, published their findings in Acta Palaeontologica Polonica, an international quarterly journal that publishes papers from all areas of paleontology.

Druckenmiller and Erickson have previously published documentation suggesting that during this time period, a distinct, polar fauna existed in what is now northern Alaska. At the time, Arctic Alaska was covered in a polar forest because the climate was much warmer. Since it was so far north, the dinosaurs had to contend with months of winter darkness and snow. “The finding of dinosaurs this far north challenges everything we thought about a dinosaur’s physiology,” Erickson said. “It creates this natural question. How did they survive up here?”

The fossil site where the discovery was made is named for geologist Robert Liscomb, who found the first dinosaur bones in Alaska while mapping along the Colville River for Shell Oil Company in 1961. At the time, Liscomb did not recognize that the bones were from a dinosaur.

Since then, museum scientists have excavated and cataloged more than 6,000 bones from the new species, primarily small juveniles estimated to have been about 9 feet long and 3 feet tall at the hips. “It appears that a herd of young animals was killed suddenly, wiping out mostly one similar-aged population to create this deposit,” Druckenmiller said.

Currently, there are three named dinosaurs documented from the North Slope, including two plant eaters and one carnivore. However, most of those species are known from incomplete material. “Ugrunaaluk is far and away the most complete dinosaur yet found in the Arctic or any polar region,” Druckenmiller said. “We have multiple elements of every single bone in the body.”

“So far, all dinosaurs from the Prince Creek Formation that we can identify as species are distinct from those found anywhere else. The recognition of Ugrunaaluk kuukpikensis provides further evidence that the dinosaurs living in polar latitudes in what is now Alaska were not the same species found from the same time periods in lower latitudes.”

The scientists completed a detailed study of all the different skull bones of this animal and compared them to close relatives. Some features were shared while others, particularly those in the skull and around the mouth, were seen only in the Alaska material. Mori, who is now a curator for the Saikai City Board of Education in Japan, said, “The new species has a unique combination of characteristics not seen in other dinosaurs. It lacks a pocket on the orbital rim, which Edmontosaurus has.”

Ancient human species discovered in South Africa?

This video says about itself:

10 September 2015

Within a deep and narrow cave in South Africa, paleoanthropologist Lee Berger and his team found fossil remains belonging to the newest member of our human family. The Homo naledi discovery adds another exciting chapter to the human evolution story by introducing an ancestor that was primitive but shared physical characteristics with modern humans.

From daily The Guardian in Britain:

Homo naledi: New species of ancient human discovered, claim scientists

Bones found in South African cave are Homo naledi, a new species of ancient human relative, say researchers, but some experts are sceptical of find

Ian Sample, Science editor

Thursday 10 September 2015 10.30 BST

A huge haul of bones found in a small, dark chamber at the back of a cave in South Africa may be the remnants of a new species of ancient human relative.

Explorers discovered the bones after squeezing through a fissure high in the rear wall of the Rising Star cave, 50km from Johannesburg, before descending down a long, narrow chute to the chamber floor 40 metres beneath the surface.

The entrance chute into the Dinaledi chamber is so tight – a mere eight inches wide – that six lightly built female researchers were brought in to excavate the bones. Footage from their cameras was beamed along 3.5km of optic cable to a command centre above ground as they worked inside the cramped enclosure.

The women recovered more than 1,500 pieces of bone belonging to at least 15 individuals. The remains appear to be infants, juveniles and one very old adult. Thousands more pieces of bone are still in the chamber, smothered in the soft dirt that covers the ground.

The leaders of the National Geographic-funded project (link to video) believe the bones – as yet undated – represent a new species of ancient human relative. They have named the creature Homo naledi, where naledi means “star” in Sesotho, a local South African language. But other experts on human origins say the claim is unjustified, at least on the evidence gathered so far. The bones, they argue, look strikingly similar to those of early Homo erectus, a forerunner of modern humans who wandered southern Africa 1.5m years ago.

“We’ve found a new species that we are placing in the genus Homo, which is really quite remarkable,” said Lee Berger, a paleoanthropologist who led the work at the University of Witwatersrand in Johannesburg. He described the slender, small-brained creatures as “long-legged”, “pinheaded” and “gangly”. The males stood about 5ft, with females a little shorter.

Measurements of the bones show that the creature has a curious blend of ancient ape and modern human-like features. Its brain is tiny, the size of a gorilla’s. Its teeth are small and simple. The thorax is primitive and ape-like, but its hands more modern, their shape well-suited to making basic tools. The feet and ankles are built for walking upright, but its fingers are curved, a feature seen in apes that spend much of their time in the trees. The findings are reported in two papers published in the online journal eLife.

The Dinaledi chamber has been visited by explorers in the past, and the soft sediments in which the bones were found have been badly disturbed. Because the remains were not encased in rock, Berger’s team has not been able to date them. They could be 3m years old, or far more modern. No other animals were found in the chamber that might hint at when the human relative got there.

“If this is an ancient species, like a coelacanth, that has come down through time and is only tens of thousands, or hundreds of thousands of years old, it means that during that time we had a complex species wandering around Africa, perhaps making tools. That would make archaeology very difficult, because we aren’t going to know who made what,” Berger said.

John Hawks, a researcher on the team, said that despite some of its modern features, Homo naledi probably belonged at the origins of our genus, Homo. “It’s telling us that evolutionary history was probably different to what we had imagined,” he said. Paul Dirks, another scientist involved, said that work was ongoing to establish the age of the bones. Some tests, such as carbon dating, will destroy the material, and will only be tried once the bones have been studied more closely.

Without knowing the age of the bones, some researchers see the fossils as little more than novelties. “If they are as old as two million years, then they might be early South African versions of Homo erectus, a species already known from that region. If much more recent, they could be a relic species that persisted in isolation. In other words, they are more curiosities than game-changers for now,” said William Jungers, an anthropologist at Stony Brook School of Medicine in New York.

Christoph Zollikofer, an anthropologist at the University of Zurich, said that many of the bone characteristics used to claim the creature as a new species are seen in more primitive animals, and by definition cannot be used to define a new species. “The few ‘unique’ features that potentially define the new species need further scrutiny, as they may represent individual variation, or variation at the population level,” he said. Tim White, a paleoanthropologist at the University of California, Berkeley, goes further. “From what is presented here, they belong to a primitive Homo erectus, a species named in the 1800s.”

The Dinaledi chamber is extremely hard to access today, raising the question of how the creatures came to be there. They may have clambered in and become stuck, or died when water filled the cave. But Berger and his colleagues favour a more radical explanation. “We have, after eliminating all of the probable, come to the conclusion that Homo naledi was utilising this chamber in a ritualised fashion to deliberately dispose of its dead,” Berger said.

The conclusion is not widely accepted by others. “Intentional disposal of rotting corpses by fellow pinheads makes a nice headline, but seems like a stretch to me,” said Jungers. Zollikofer agrees. “The ‘new species’ and ‘dump-the-dead’ claims are clearly for the media. None of them is substantiated by the data presented in the publications,” he said. Hawks is open to other explanations, but said that disposal made sense. “The evidence really tends to exclude the idea that they entered the chamber one at a time, alive, over some time, because we have infants, small children, and very old adults who would almost certainly not have managed to get into this chamber without being deposited there.”

Chris Stringer, head of human origins at the Natural History Museum in London, said that how the creatures reached their final resting place was a “big puzzle”.

“If we’re talking about intentional disposal, we’re talking about creatures with a brain the size of a gorilla’s going deep into a cave, into the dark, and posting bodies through a small fissure into this cave chamber. It’s remarkably complex behaviour for what we’d think of as a very primitive human-like species. Whether there are other explanations remains to be seen, but it’s one of the plausible explanations,” he said.

MEET THE NEWLY DISCOVERED HUMAN SPECIES “Acting on a tip from spelunkers two years ago, scientists in South Africa discovered what the cavers had only dimly glimpsed through a crack in a limestone wall deep in the Rising Star cave: lots and lots of old bones. The remains covered the earthen floor beyond the narrow opening. This was, the scientists concluded, a large, dark chamber for the dead of a previously unidentified species of the early human lineage — Homo naledi.” Check out this Q&A with the leader of the expedition. [NYT]

Scientists have discovered a new species of human ancestor deep in a South African cave, adding a baffling new branch to the family tree. By Jamie Shreeve, National Geographic: here.