The Unbroken Thread

A new dinosaur named Brontomerus mcintoshi, or “thunder-thighs” after its enormously powerful thigh muscles, has been discovered in Utah, USA. The new species is described in a paper recently published in the journal Acta Palaeontologica Polonica by an international team of scientists from the UK and the US.

A member of the long-necked sauropod group of dinosaurs which includes Diplodocus and Brachiosaurus, Brontomerus may have used its powerful thighs as a weapon to kick predators, or to help travel over rough, hilly terrain. Brontomerus lived about 110 million years ago, during the Early Cretaceous Period, and probably had to contend with fierce “raptors” such as Deinonychus and Utahraptor.

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The shape of the bone indicates that the animal would likely have had the largest leg muscles of any dinosaur in the sauropod family. This is reflected in the name Brontomerus, which literally means “thunder-thighs.” The dinosaur’s species name, mcintoshi, was chosen in honor of John “Jack” McIntosh, a retired physicist at Wesleyan University, Conn., and lifelong avocational paleontologist.

I would never have imagined something so large could support itself and maneuver its body well enough to use kicks to defend itself! It sounds like there’s no direct evidence for this, but it is an exciting possibility.

(Source: sciencedaily.com)

thisisfoolishreally:

this,

and this,

and also this, 

and all these:

…..were all made by accident?

On the contrary: Evolution is no accident, and while evolution certainly happens for a reason, it does not happen for a purpose, as creationists insist. The selection of beneficial genes (and the selection against harmful genes) for roughly 4 billion years has given us the wonderfully varied forms of life that surround us.

In fact, many complex systems have very simple origins. Bees pollinate flowers because flowers bribe them with food. Flowers bribe bees with food because it is more efficient to produce a small amount of pollen than to fill the entire air with pollen as gymnosperms do. If even one plant has an advantage over its peers by bribing bees into doing their pollination for them, over many generations their descendants will become more proliferate than their competitors.

Even the brilliant plumage of the Mandarin duck (which pales in comparison to the even more fantastic plumage and displays of the birds of paradise) is easily explained through sexual selection. Female Mandarin ducks just find colorful plumage sexy—which, in many bird species, is thought to be due to bright plumage signalling a good diet and good health—so colorful male Mandarin ducks have an advantage over their less colorful kin and eventually outbreed them.

Even the golden child of creationist “proof” for intelligent design, the eye, has humble origins as photosensitive cells clustered together simply to detect whether light was present or not. This graphic provides a nice summary of the different stages of evolution for the eye. I would also like to point out that, despite its complexity, the eye has many flaws. Blind spots, grainy night vision, and we can’t even see all the colors that birds and some types of shrimp see! A strange fact for something designed by a creator and made entirely in their image, but perfect sense when you take into account evolution.

(via munchalittlehappiness-deactivat)

Scientists have favored a model of evolution in which beneficial gene mutations quickly and dramatically sweep through a population due to the evolutionary advantages they confer. Such mutations would become nearly universal in a population. But this selective sweep model may not be accurate for humans, a new study indicates. Human evolution likely followed a more subtle and complicated path, say population geneticists Molly Przeworski of the University of Chicago and Guy Sella of Hebrew University of Jerusalem and colleagues.

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It may have been difficult for selective sweeps to take hold in humans because of demographics, Clark says. People are scattered throughout the globe, so a beneficial mutation would have a long way to spread. Such a mutation would have to have dramatic effects on evolutionary fitness to go global.

Good evidence does exist for some mutations that did undergo selective sweeps in humans, such as those for skin pigmentation, hair and teeth morphology and the genetic change that allows adults in some populations to digest the milk sugar lactose. But those examples are the exception rather than the rule in human evolution.

The rest of the article discusses the findings more in depth. This is definitely intriguing, and I’d like to take a stab in the dark and guess that the lack of genetic sweeps are due to human intelligence rather than distance… we can solve many of our own problems that other species simply don’t have the capability for, so we don’t need to evolve thicker hair, stronger jaws, etc.

Now what would be really interesting is doing the same study, only with local populations. If genetic sweeps are rare even in local populations, that would make a good argument for intelligence ridding us of most of the problems other species turn to evolution to solve.

(Source: sciencenews.org)

In the upcoming issue of the journal Nature, the anthropologists question the claims that several prominent fossil discoveries made in the last decade are our human ancestors. Instead, the authors offer a more nuanced explanation of the fossils’ place in the Tree of Life. They conclude that instead of being our ancestors the fossils more likely belong to extinct distant cousins.

“Don’t get me wrong, these are all important finds,” said co-author Bernard Wood, University Professor of Human Origins and professor of Human Evolution Anatomy at GW and director of its Center for the Advanced Study of Hominid Paleobiology. “But to simply assume that anything found in that time range has to be a human ancestor is naïve.”

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“We are not saying that these fossils are definitively not early human ancestors,” said co-author Terry Harrison, a professor in NYU’s Department of Anthropology and director of its Center for the Study of Human Origins. “But their status has been presumed rather than adequately demonstrated, and there are a number of alternative interpretations that are possible. We believe that it is just as likely or more likely that they are fossil apes situated close to the ancestry of the living great ape and humans.”

While a reasonable and good point, especially considering the media’s tendency to sensationalize any fossil find, I feel it’s something that was probably better left unsaid. The nuance is irrelevant to most people, and all creationists are going to take away from it is that there is still debate about human ancestors and thus evolution.

(Source: sciencedaily.com)

The team recorded and quantified the captive birds’ night-time restlessness – a proxy for migratory behaviour in the wild – and took blood samples to look for genetic signatures that could account for variations in nocturnal activity.

They focused on four genes linked to daily rhythms, changes in which might encourage the birds to migrate at night. Nocturnal restlessness was found to be linked to the gene ADCYAP1. The longer the form of the gene, or allele, the more restless the blackcap.

The gene may do more than simply encourage night-time fidgeting: it encodes a protein called PACAP, which plays a major role in melatonin secretion, energy metabolism and feeding. These functions are crucial for preparing birds for long flights. “This is the first step to bringing research on avian migration down to the molecular level,” says Mueller.

It will be interesting to see if this gene is consistent in all migratory birds. If it is, could it stretch back even to the ancestors migratory mammals share with birds? My guess would be convergent evolution rather than it being that old, but I would love to be pleasantly surprised.

(Source: newscientist.com)

A fossilized foot bone recovered from Hadar, Ethiopia, shows that by 3.2 million years ago human ancestors walked bipedally with a modern human-like foot, a report that appears Feb. 11 in the journal Science, concludes. The fossil, a fourth metatarsal, or midfoot bone, indicates that a permanently arched foot was present in the species Australopithecus afarensis, according to the report authors, Carol Ward of the University of Missouri, together with William Kimbel and Donald Johanson, of Arizona State University’s Institute of Human Origins.

The research helps resolve a long-standing debate between paleoanthropologists who think A. afarensis walked essentially as modern humans do and those who think this species practiced a form of locomotion intermediate between the quadrupedal tree-climbing of chimpanzees and human terrestrial bipedalism. The question of whether A. afarensis had fully developed pedal, or foot, arches has been part of this debate. The fourth metatarsal described in the Science report provides strong evidence for the arches and, the authors argue, support a modern-human style of locomotion for this species.

How exciting to discover such strong evidence for bipedalism so early in human evolution! And yet it only opens up the question of how much earlier it evolved, if A. afarensis was not the first…

(Source: sciencedaily.com)

Dollo’s Law, a theory proposed by the scientist Louis Dollo in the 1800s, states that when a particular trait is lost in a species, it never comes back.

It’s one explanation for why humans no longer have tails, birds and turtles are toothless and snakes have stayed limbless.

But a new analysis, done by a researcher at Stony Brook University, found that while frogs lost teeth in the lower jaw at least 200 million years ago, a particular type of marsupial tree frog regained those lower teeth about 20 million years ago.

“It’s a very clear-cut case of re-evolution because of the large time span,” said John Wiens, the Stony Brook biologist who authored the paper in the journal Evolution.

Although interesting, this shouldn’t be too surprising to anyone. People are occasionally born with “tails” (just as snakes and dolphins are sometimes born with “leg” nubs), and while that particular mutation doesn’t offer any particular selective advantage to people (or snakes/dolphins), the potential benefits of frogs with teeth are obvious.

My initial guess to the question posed for why other frogs hadn’t re-evolved teeth would be that teeth give the marsupial tree frog some special advantage in catching prey that makes it worth the calcium expenditure to produce teeth, whereas teeth might not give other frogs much of an advantage. Or perhaps other species would benefit but just haven’t had the necessary mutation to begin growing teeth again. I’ll be looking forward to any follow up research on this!

(Source: The New York Times)

The research, published online this week in the journal Soft Matter, shows that clay vesicles provide an ideal container for the compartmentalization of complex organic molecules.

The authors say the discovery opens the possibility that primitive cells might have formed inside inorganic clay microcompartments.

The idea that biological reactions could have taken place inside clay “cells” until life advanced enough to form a cell wall is an exciting one! If evidence can be found this actually did happen during evolutionary history it would strike (another) serious blow to the argument that life is too “complex” to simply pop into existence.

(Source: physorg.com)

A novel X-ray imaging technology is helping scientists better understand how in the course of evolution snakes have lost their legs. The researchers hope the new data will help resolve a heated debate about the origin of snakes: whether they evolved from a terrestrial lizard or from one that lived in the oceans. New, detailed 3-D images reveal that the internal architecture of an ancient snake’s leg bones strongly resembles that of modern terrestrial lizard legs.

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Only three specimens exist of fossilised snakes with preserved leg bones. Eupodophis descouensi, the ancient snake studied in this experiment, was discovered ten years ago in 95-million-year-old rocks in Lebanon. About 50 cm long overall, it exhibits a small leg, about 2 cm long, attached to the animal’s pelvis. This fossil is key to understanding the evolution of snakes, as it represents an intermediate evolutionary stage when ancient snakes had not yet completely lost the legs they inherited from earlier lizards. Although the fossil exhibits just one leg on its surface, a second leg was thought to be concealed in the stone, and indeed this leg was revealed in full detail thanks to synchrotron X-rays.

It goes on to suggest that during snake evolution they lost legs because it simply stopped developing earlier and earlier in fetal/young snake development, until they weren’t developing at all. Amazing!

(Source: sciencedaily.com)

African elephants have new distant cousins — other African elephants.

A genetic analysis of elephants and their extinct relatives, woolly mammoths and mastodons, shows that forest-dwelling African elephants are a separate species from Africa’s savanna elephants. 

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Forest and savanna elephants evolved into different species from a common ancestor between 2.6 million and 5.6 million years ago, the new analysis reveals. That’s about the same time as Asian elephants and woolly mammoths came to a fork in their family trees. Asian elephants and mammoths’ many differences mean that some not only consider the animals distinct species but different genera — another level of taxonomic hierarchy.

“If you believe that the mammoth and the Asian elephant are different species, then it’s very difficult to argue that the forest and savanna elephants aren’t separate species,” says David Reich, an evolutionary geneticist at Harvard Medical School in Boston and coauthor of the study.

(Source: sciencenews.org)