Repenomamus is a gobiconodontid mammal genus containing two species, R. robustus and R. giganticus. Both species are known from fossils found in China that date to the early Cretaceous period, about 125 million years ago. R. robustus is the only Mesozoic mammal for which there is good evidence that it fed on small vertebrates, including young dinosaurs, though it is not possible to determine if it actively hunted live dinosaurs or scavenged dead ones. R. giganticus is the largest mammal known from the Mesozoic era…

(read more: Wikipedia)

illustration of R. robustus by Dmitry Bogdanov; photo of skull fossil of R. giganteus by Laikayiu

Dingoes Aren’t Just Wild Dogs
Rather than being the descendants of feral mutts, dingoes are actually in their own unique taxonomical corner
by Rachel Nuwer
Dingoes might look like your run-of-the-mill mongrel pooch, and for years, researchers assumed the dingo’s ancestors were domesticated dogs from East Asia that subsequently went wild. But it turns out that dingoes are more unique than that. They are not only a distinct species, but also a distinct group of predators, separate from dogs and wolves, The Scientist reports.
Dingoes arrived in Australia several thousands years ago, and they were first mentioned as a species in 1793. At that time, they were called Canis dingo. However, their official name was soon changed to Canis lupus dingo, on the assumption that dingoes were, in fact, a subspecies of wolf and within the same evolutionary clade as domestic dogs.
In a new study, researchers challenged that assumption. They examined 69 dingo skulls that dated back to 1900 or earlier—presumably before dingoes would have encountered and interbred with domesticated dogs, which only arrived in Australia when Europeans did. Dingoes, the researchers found, have anatomical features that set them apart from dogs and wolves, including a wider head and longer snout, The Scientist writes. The team also found that dingoes don’t necessarily have to be tan-colored; they can be black, white or dark brown, too…
(read more: http://www.smithsonianmag.com/smart-news/dingoes-arent-just-wild-dogs-180950384/?utm_source=facebook.com&no-ist)
photo: PartnerHund

Dingoes Aren’t Just Wild Dogs

Rather than being the descendants of feral mutts, dingoes are actually in their own unique taxonomical corner

by Rachel Nuwer

Dingoes might look like your run-of-the-mill mongrel pooch, and for years, researchers assumed the dingo’s ancestors were domesticated dogs from East Asia that subsequently went wild. But it turns out that dingoes are more unique than that. They are not only a distinct species, but also a distinct group of predators, separate from dogs and wolves, The Scientist reports.

Dingoes arrived in Australia several thousands years ago, and they were first mentioned as a species in 1793. At that time, they were called Canis dingo. However, their official name was soon changed to Canis lupus dingo, on the assumption that dingoes were, in fact, a subspecies of wolf and within the same evolutionary clade as domestic dogs.

In a new study, researchers challenged that assumption. They examined 69 dingo skulls that dated back to 1900 or earlier—presumably before dingoes would have encountered and interbred with domesticated dogs, which only arrived in Australia when Europeans did. Dingoes, the researchers found, have anatomical features that set them apart from dogs and wolves, including a wider head and longer snout, The Scientist writes. The team also found that dingoes don’t necessarily have to be tan-colored; they can be black, white or dark brown, too…

(read more: http://www.smithsonianmag.com/smart-news/dingoes-arent-just-wild-dogs-180950384/?utm_source=facebook.com&no-ist)

photo: PartnerHund

One person above all others can be regarded as the ‘parent’ of the Speculative Zoology Movement, his several books and innumerable ideas inspiring virtually everything that’s appeared since. I refer of course to writer, artist, editor, consultant and visionary Dougal Dixon, author of a huge number of books and winner of an intimidating number of awards relating to educational journalism and authorship. Dougal has been the go-to person for speculative zoology ever since the 1981 publication of his famous, beautifully illustrated book After Man (Dixon 1981). This was followed by The New Dinosaurs (Dixon 1988), a book that told the story of a parallel Earth where the end-Cretaceous extinction event never occurred, and Man After Man (Dixon 1990), a fantastic and slightly disturbing look at a possible future for humankind. Dougal was also substantially involved in the TV series The Future Is Wild and wrote the accompanying book (Dixon & Adams 2004). And then there’s Greenworld (Dixon 2010), on which more below…

The Trouble With Turtles: Paleontology at a Crossroads

Scientists debate whether modern turtles are more closely related to snakes and lizards or birds and crocodiles.

by Naomi Lubick

Traditional paleontological research has been upended over the past few decades, as less traditional fields, such as genomics and developmental biology, have weighed in on vertebrate evolution. Researchers have examined the lingering color elements in dinosaur feathers, the genetics of woolly mammoths, purported proteins and blood from dinosaurs, and other ancient fossil signatures using modern tools. But the question of turtle evolution has remained resistant to both traditional and novel methods.

More than 300 species of turtles exist today, but where they came from isn’t entirely clear. Turtles are the last big living vertebrate group to be placed firmly on the tree of life, and the arguments are getting messy. Three fields in particular — paleontology, developmental biology and microbiology/genomics — disagree about how, and from what, turtles may have evolved.

Traditional paleontologists have placed turtles, which are indisputably reptiles, in relation to a group of mostly extinct reptilian animals called anapsids, which don’t have holes in their skulls; however, analyses in the 1990s put turtles in the diapsid camp, which originally had two holes in their skulls, and closer to modern reptiles like snakes. Morphology places them near the group made up of lizards and birds and crocodiles…

(read more: EARTH Magazine)

images: T - Kathleen Cantner, AGI.; Bottom 3 - Tyler Lyson, NMNH

treehugga asked:

Are there any ideas as the evolutionary reason for eyebrows? Is it because as speech progressed we needed ways to express ourselves? I was just thinking today how odd it is that of all parts of the face hair grows there on females even though they don't grow any other facial hair like men do due to hormones. Do you have any thoughts or links?? Thanks!

well some popular ideas for the evolutionary advantage of eyebrows are:

they help keep sweat and particulate matter out of the eyes, along with the structure of the brow ridge

it could also be another way to detect small insects and debris on the face, before it gets into the eye (and damage it), giving a person advance warning to remove such things from the face before they enter the eye. working as vibrissae (whiskers).

there is also the idea, of course, popularaized by British naturalist Desmond Morris, and others, that the eye brows aid so much in communication that they provide an evolutionary advantage. we are of course cooperative creatures, who rely a great deal on effective communication of intention and interpretation of mood, etc.

some people believe that when humans began sleeping on the ground, they became exposed to all sorts of nocturnal predators. many predators, like tigers, tend not to attack people face on, when they can see the eyes (but like to attack from behind or when the animal/human is sleeping.) the idea is that the line of the eyelashes and the line of the eye brow form an “eye spot” that may look like an open eye in the dark to some predators… this seems like a bit of a stretch to me, but its an idea that’s out there.

YOUR INNER FISH | Tritheledont | PBS

The Bay of Fundy in Nova Scotia, Canada, is home not only to the world’s largest tides, but also to some incredibly important fossils. Paleontologist Neil Shubin describes one particularly striking specimen from these cliffs: an animal in the midst of the reptile-to-mammal transition.

YOUR INNER FISH premieres Wednesday, April 9 at 10/9c following NATURE at 8/7c and NOVA at 9/8c as part of PBS’ THINK WEDNESDAY.

PBS:  Your Inner Fish - LUCY

Fossils of human ancestors from millions of years ago can be found in the rocks of Ethiopia. Paleontologist Don Johanson recounts his discovery of one iconic fossil, and the impact it had on our understanding of where we come from.

YOUR INNER FISH premieres Wednesday, April 9 at 10/9c following NATURE at 8/7c and NOVA at 9/8c as part of PBS’ THINK WEDNESDAY.

YOUR INNER FISH | Our Fishy Brains | PBS

While the human brain may seem exceptional, the truth is that it has some deep similarities with many other animals’, including fish. Anatomist Neil Shubin dissects a fish brain and a human brain and shows us how much we have in common with sea-dwelling creatures.

YOUR INNER FISH premieres Wednesday, April 9 at 10/9c following NATURE at 8/7c and NOVA at 9/8c as part of PBS’ THINK WEDNESDAY.

Controversies From the World of Ratite and Tinamou Evolution

by Darren Naish

As blasphemous and offensive as it seems to say it, birds are pretty samey. Generally speaking, they’re small flying things with long forelimbs, proportionally large heads with big, globular braincases, and grasping feet where an enlarged first toe (the hallux) opposes the remaining three. A shape like this was – so both the fossil record and inferences made from cladograms show us – ancestral for modern birds, so any bird that deviates from it is weird indeed.

Cue ratites. Gigantic, long-legged, flightless birds with proportionally small heads, short, ridiculously short, or absent wings, they are the closest that any bird group comes to recapturing the body form (and presumably lifestyle) of non-bird dinosaurs.

Conventionally, the term ‘ratite’ is used for the kiwi-emu-rhea-ostrich clade (even though it always feels a bit weird to regard kiwi as ratites). The 11 or so recently extinct moa of New Zealand and the also recently extinct elephant birds or aepyornithids of Madagascar are also clearly members of this group, and then there are a handful of fossil groups as well.

But there’s another modern group we have to consider here: the tinamous of South, Central and southern North America. All 40 or so species are small compared to ratites, capable of flight, and superficially galliform-like. They lack the anatomical specialisations that make ratites so remarkable, like an unkeeled, raft-like sternum, reduced, atrophied or absent forelimbs, proportionally long legs and neck, loose, ‘decomposed’ plumage, and so on…

(read more: Tetrapod Zoology - Scientific American)

top illustration and bttm photos by D. Naish

"Little Foot" Fossil Could Be Human Ancestor
by Michael Balter
He may be called Little Foot, but for human evolution researchers he’s a big deal: His is the most complete skeleton known of an early member of the human lineage. Ever since the skeleton was discovered in a South African cave in the 1990s and named for its relatively small foot bones, researchers have been fiercely debating how old it is, with estimates ranging from about 2 million years to more than 3 million. A new geological study of the cave concludes that Little Foot is at least 3 million years old. If correct, that would mean he is old enough to be a direct ancestor of today’s humans, and could shift South Africa to the forefront of human evolution.
The first traces of the skeleton were found in the early 1990s by Ron Clarke, a paleoanthropologist at the University of the Witwatersrand in Johannesburg, South Africa. He was rummaging through boxes of animal bones previously excavated in the Sterkfontein caves, about 40 kilometers northwest of Johannesburg, where a number of fossils of australopithecines—advanced apes similar to the famous Lucy—have been discovered. Clarke found four small australopithecine foot bones, and set off with his team to unearth the skeleton that they came from…
(read more: Science News/AAAS)
photo: Ron Clarke

"Little Foot" Fossil Could Be Human Ancestor

by Michael Balter

He may be called Little Foot, but for human evolution researchers he’s a big deal: His is the most complete skeleton known of an early member of the human lineage. Ever since the skeleton was discovered in a South African cave in the 1990s and named for its relatively small foot bones, researchers have been fiercely debating how old it is, with estimates ranging from about 2 million years to more than 3 million. A new geological study of the cave concludes that Little Foot is at least 3 million years old. If correct, that would mean he is old enough to be a direct ancestor of today’s humans, and could shift South Africa to the forefront of human evolution.

The first traces of the skeleton were found in the early 1990s by Ron Clarke, a paleoanthropologist at the University of the Witwatersrand in Johannesburg, South Africa. He was rummaging through boxes of animal bones previously excavated in the Sterkfontein caves, about 40 kilometers northwest of Johannesburg, where a number of fossils of australopithecines—advanced apes similar to the famous Lucy—have been discovered. Clarke found four small australopithecine foot bones, and set off with his team to unearth the skeleton that they came from…

(read more: Science News/AAAS)

photo: Ron Clarke

Hybrid Dolphin Gives Scientists Rare Window into Evolution
by Zoë Shribman
You’ve seen DNA analysis on every forensic criminology show on TV. Normally, it leads detectives to the killer, but in another case—this one on the open ocean—it has led scientists to a hybrid dolphin.
The clymene dolphin (Stenella clymene) is something of a biological riddle. Though these animals were first declared their own species by the American Society of Mammalogists in 1981, they were originally thought to be a subspecies of the spinner dolphin (S. longirostris), despite their similarities to the striped dolphin (S. coeruleoalba). DNA analysis has solved the puzzle, conclusively stating that clymene dolphins are a distinct species.
In her study, Ana Amaral at the University of Lisbon collected both mitochondrial and nuclear DNA from 72 individuals of the three similar dolphin species. Mitochondrial DNA is passed on through the organism’s mother, whereas nuclear DNA comes from both parents. Here, analyzing both was key. In her analysis, Amaral found that the DNA from the nucleus was most similar to the spinner dolphin, while DNA from the mitochondria was most similar to the striped dolphin…
(read more: PBS - NovaNext)                        (photo: NOAA)

Hybrid Dolphin Gives Scientists Rare Window into Evolution

by Zoë Shribman

You’ve seen DNA analysis on every forensic criminology show on TV. Normally, it leads detectives to the killer, but in another case—this one on the open ocean—it has led scientists to a hybrid dolphin.

The clymene dolphin (Stenella clymene) is something of a biological riddle. Though these animals were first declared their own species by the American Society of Mammalogists in 1981, they were originally thought to be a subspecies of the spinner dolphin (S. longirostris), despite their similarities to the striped dolphin (S. coeruleoalba). DNA analysis has solved the puzzle, conclusively stating that clymene dolphins are a distinct species.

In her study, Ana Amaral at the University of Lisbon collected both mitochondrial and nuclear DNA from 72 individuals of the three similar dolphin species. Mitochondrial DNA is passed on through the organism’s mother, whereas nuclear DNA comes from both parents. Here, analyzing both was key. In her analysis, Amaral found that the DNA from the nucleus was most similar to the spinner dolphin, while DNA from the mitochondria was most similar to the striped dolphin…

(read more: PBS - NovaNext)                        (photo: NOAA)

Remnants of an Ancient Forest provide Ecological Context for Early Miocene Fossil Apes  [2014]
The lineage of apes and humans (Hominoidea) evolved and radiated across Afro-Arabia in the early Neogene during a time of global climatic changes and ongoing tectonic processes that formed the East African Rift.
These changes probably created highly variable environments and introduced selective pressures influencing the diversification of early apes. However, interpreting the connection between environmental dynamics and adaptive evolution is hampered by difficulties in locating taxa within specific ecological contexts: time-averaged or reworked deposits may not faithfully represent individual palaeohabitats.
Here we present multiproxy evidence from Early Miocene deposits on Rusinga Island, Kenya, which directly ties the early ape Proconsul to a widespread, dense, multistoried, closed-canopy tropical seasonal forest set in a warm and relatively wet, local climate. These results underscore the importance of forested environments in the evolution of early apes.
read paper: dx.doi.org/10.1038/ncomms4236
(via: NovaTaxa - Species New to Science)

Remnants of an Ancient Forest provide Ecological Context for Early Miocene Fossil Apes  [2014]

The lineage of apes and humans (Hominoidea) evolved and radiated across Afro-Arabia in the early Neogene during a time of global climatic changes and ongoing tectonic processes that formed the East African Rift.

These changes probably created highly variable environments and introduced selective pressures influencing the diversification of early apes. However, interpreting the connection between environmental dynamics and adaptive evolution is hampered by difficulties in locating taxa within specific ecological contexts: time-averaged or reworked deposits may not faithfully represent individual palaeohabitats.

Here we present multiproxy evidence from Early Miocene deposits on Rusinga Island, Kenya, which directly ties the early ape Proconsul to a widespread, dense, multistoried, closed-canopy tropical seasonal forest set in a warm and relatively wet, local climate. These results underscore the importance of forested environments in the evolution of early apes.

read paper: dx.doi.org/10.1038/ncomms4236

(via: NovaTaxa - Species New to Science)

Sponges Likely Paved the Way For All Life on Earth
 by Jennifer Viegas
The seemingly lowly sponge, just by its very existence, might have paved the way for the evolution of complex life forms, including our own species, according to a new paper.
Sponges appear to have added oxygen to the deep ocean, creating an environment where more mobile, major oxygen-using animals could have evolved, holds the paper, published in the latest Nature Geoscience.
The research builds on work, presented earlier this year, which found that the most primitive sponges probably could survive in water containing very low levels of oxygen…
(read more: Discovery News)
photo: Deep Sea Expedition, 2007, NOAA-OE

Sponges Likely Paved the Way For All Life on Earth

by Jennifer Viegas

The seemingly lowly sponge, just by its very existence, might have paved the way for the evolution of complex life forms, including our own species, according to a new paper.

Sponges appear to have added oxygen to the deep ocean, creating an environment where more mobile, major oxygen-using animals could have evolved, holds the paper, published in the latest Nature Geoscience.

The research builds on work, presented earlier this year, which found that the most primitive sponges probably could survive in water containing very low levels of oxygen…

(read more: Discovery News)

photo: Deep Sea Expedition, 2007, NOAA-OE

Evolution is just a theory, right?

Not entirely, and no not the way you mean it, so let’s say…

No, and here’s why. There is an overwhelming body of evidence that evolution occurs, and has occurred over the duration of life on Earth. There is simply too much evidence to honestly consider the phenomenon of evolution as a “theory”, even though it IS a scientific theory. I like to say though, that evolution is a fact.

At one time there were no chimps, but there were Deinoneichus. Now, there are chimps and no animals recognizable a Deinoneichus…

We can actually watch organisms, like fruit flies, evolve over generations in much less than a human life time. The selective breeding of domestic animals over time is evolution in action (look at the various forms/breeds of pig, cow, dog, and other animals that have departed radically in form from their wild sources). There is the evidence from comparative embryology of vertebrates, modern knowledge of genetics and rates of genetic variation, the fossil record and geologic stratigraphy, knowledge of zoogeography, understanding of plate tectonics and continental drift, the ability to date both rock and organic material with an amazing amount of accuracy, comparative anatomy and physiology, and comparative biochemistry. 

At this point, there is simply too much evidence AND direct observation to classify evolution as a theory in the popular sense f the word. It is fact. There simply is no reasonable conclusion one can reach scientifically, after over 200 years of work in geology, zoology, genetics, chemistry and a variety of other fields have independently lead us in this direction.

Life on Earth did not start as it is now. It started in a very simple way, probably from one kind of organism, and it branched out into the multitude of complex forms you see today… you and me and the snail and the oak tree, etc. Life continues to evolve right now. Selective pressures and horizontal gene transfer and random genetic mutation are working to change organisms as populations, slightly ever so slightly so that one day they will be markedly different organisms.

To understand all this, one does need to read a bit, but there is so much evidence, there has been so much work… there are very good reasons that the VAST MAJORITY of scientists operate under the framework of evolution, as scientists. I do not use the word “believe”, no more than i would state that I believe that there is gravity or that water will evaporate at a certain temperature under certain conditions.

If you have any more comments or questions about evolution, or the theories of how it operates, feel free to ask. Also, the work is there…

http://rhamphotheca.tumblr.com/tagged/evolution