palaeopedia
palaeopedia:

The first whale, Protocetus (1904)
Phylum : ChordataClass : MammaliaOrder : CetaceaSuborder : ArchaeocetiFamily : ProtocetidaeGenus : ProtocetusSpecies : P. atavus
Middle Eocene (42 - 38 Ma)
2,5 m long and 100 kg (size)
Mokattam formation, Egypt (map)
Despite its name, Protocetus wasn’t technically the “first whale;” as far as we know, that honor belongs to the four-legged, land-bound Pakicetus, which lived a few million years earlier.
Whereas the dog-like Pakicetus ventured only occasionally into the water, Protocetus was much better adapted to an aquatic lifestyle, with a lithe, seal-like body and powerful front legs. Also, the nostrils of this prehistoric whale were located midway up its forehead, foreshadowing the blowholes of its modern descendants, and its ears were better adapted to hearing underwater.

palaeopedia:

The first whale, Protocetus (1904)

Phylum : Chordata
Class : Mammalia
Order : Cetacea
Suborder : Archaeoceti
Family : Protocetidae
Genus : Protocetus
Species : P. atavus

  • Middle Eocene (42 - 38 Ma)
  • 2,5 m long and 100 kg (size)
  • Mokattam formation, Egypt (map)

Despite its name, Protocetus wasn’t technically the “first whale;” as far as we know, that honor belongs to the four-legged, land-bound Pakicetus, which lived a few million years earlier.

Whereas the dog-like Pakicetus ventured only occasionally into the water, Protocetus was much better adapted to an aquatic lifestyle, with a lithe, seal-like body and powerful front legs. Also, the nostrils of this prehistoric whale were located midway up its forehead, foreshadowing the blowholes of its modern descendants, and its ears were better adapted to hearing underwater.

Mysterious 500 Million-Year-Old Ocean Predators Could Be the Ancestors of Spiders
by Annalee Newitz
Anomalocarids are one of the oldest families of animals on Earth, and they looked like nightmarish sea scorpions. But a new fossil discovery actually contains traces of their brain structure — and amazingly, their half-billion-year-old brains look a lot like an arachnid’s.
Though some anomalocarids may have been as big as 7 feet long, these newly-discovered specimens are closer to the size of today’s arachnids. The critters you see fossilized below are about 8 cm long. Still, they look pretty insane — especially when you consider that their segmented heads are so similar to what we’d see in an arachnid today. A team of paleontologists led by Peiyun Cong found the three gorgeously-preserved anomalocarid fossils in Yunnan Province, and described them today in Nature…
(read more at io9)
Anomalocarid illustration by John Meszaros

Mysterious 500 Million-Year-Old Ocean Predators Could Be the Ancestors of Spiders

by Annalee Newitz

Anomalocarids are one of the oldest families of animals on Earth, and they looked like nightmarish sea scorpions. But a new fossil discovery actually contains traces of their brain structure — and amazingly, their half-billion-year-old brains look a lot like an arachnid’s.

Though some anomalocarids may have been as big as 7 feet long, these newly-discovered specimens are closer to the size of today’s arachnids. The critters you see fossilized below are about 8 cm long. Still, they look pretty insane — especially when you consider that their segmented heads are so similar to what we’d see in an arachnid today. A team of paleontologists led by Peiyun Cong found the three gorgeously-preserved anomalocarid fossils in Yunnan Province, and described them today in Nature

(read more at io9)

Anomalocarid illustration by John Meszaros

Flightless dino-bird wore full-body feathers
New Archaeopteryx fossil complicates plumage evolution
by Thomas Sumner
A fully feathered fossil of the dinosaur-like bird Archaeopteryx is ruffling scientists’ understanding of what drove early feather evolution, scientists report July 2 in Nature.
Archaeopteryx was one of the earliest birds, spanning the evolutionary gap between feathered dinosaurs and modern birds. The flightless fowl roamed 150 million years ago during the Jurassic period and grew to the size of a well-fed pigeon.
Paleontologist Christian Foth of the Ludwig Maximilian University of Munich and colleagues examined a recently unearthed Archaeopteryx fossil, only the 11th known specimen. While Archaeopteryx is known for its feathers, the well-preserved fossil has quill-like feathers not only on the wings and tail but also on its body and legs…
(read more: Science News)
images: model - Bavarian State Archaeological Collection; fossil - Helmut Tischlinger

Flightless dino-bird wore full-body feathers

New Archaeopteryx fossil complicates plumage evolution

by Thomas Sumner

A fully feathered fossil of the dinosaur-like bird Archaeopteryx is ruffling scientists’ understanding of what drove early feather evolution, scientists report July 2 in Nature.

Archaeopteryx was one of the earliest birds, spanning the evolutionary gap between feathered dinosaurs and modern birds. The flightless fowl roamed 150 million years ago during the Jurassic period and grew to the size of a well-fed pigeon.

Paleontologist Christian Foth of the Ludwig Maximilian University of Munich and colleagues examined a recently unearthed Archaeopteryx fossil, only the 11th known specimen. While Archaeopteryx is known for its feathers, the well-preserved fossil has quill-like feathers not only on the wings and tail but also on its body and legs…

(read more: Science News)

images: model - Bavarian State Archaeological Collection; fossil - Helmut Tischlinger

libutron
libutron:

Lerista skinks and the evolution of limb loss
The Australian scincid clade Lerista (Scincidae) provides perhaps the best available model for studying limb reduction in squamates (lizards and snakes), comprising more than 75 species.
Among extant tetrapods, Lerista is exceptional in comprising a large number of closely-related species displaying prodigious variability of body form; several species possessing well-developed, pentadactyl limbs resemble typical non-fossorial scincids in body proportions, while many other species exhibit varying degrees of limb reduction and body elongation, including two that are highly elongate and entirely limbless.
Inferred phylogeny reveals extraordinary evolutionary mutability of limb morphology in Lerista. Ancestral state reconstructions indicate at least ten independent reductions in the number of digits from a pentadactyl condition.
An estimated age of 13.4 million years for Lerista entails that limb reduction has occurred not only repeatedly, but also very rapidly. At the highest rate, complete loss of digits from a pentadactyl condition is estimated to have occurred within 3.6 million years.
A relatively recent research about the phylogeny and evolution of Lerista, hypothesizes that an increase in the extent of seasonally dry and arid habitats coincident with the origination of the genus would have facilitated limb reduction and body elongation by furnishing an environment conducive to the adoption of fossorial habit.
The photo shows a Pilbara Flame-tailed Slider orRedtail Lerista, Lerista flammicauda, endemic to West Australia and found only in the Pilbara shrublands and the Western Australian Mulga shrublands.
References: [1] - [2] - [3]
Photo credit: ©Jordan Vos
Locality: The Pilbara, Western Australia

libutron:

Lerista skinks and the evolution of limb loss

The Australian scincid clade Lerista (Scincidae) provides perhaps the best available model for studying limb reduction in squamates (lizards and snakes), comprising more than 75 species.

Among extant tetrapods, Lerista is exceptional in comprising a large number of closely-related species displaying prodigious variability of body form; several species possessing well-developed, pentadactyl limbs resemble typical non-fossorial scincids in body proportions, while many other species exhibit varying degrees of limb reduction and body elongation, including two that are highly elongate and entirely limbless.

Inferred phylogeny reveals extraordinary evolutionary mutability of limb morphology in Lerista. Ancestral state reconstructions indicate at least ten independent reductions in the number of digits from a pentadactyl condition.

An estimated age of 13.4 million years for Lerista entails that limb reduction has occurred not only repeatedly, but also very rapidly. At the highest rate, complete loss of digits from a pentadactyl condition is estimated to have occurred within 3.6 million years.

A relatively recent research about the phylogeny and evolution of Lerista, hypothesizes that an increase in the extent of seasonally dry and arid habitats coincident with the origination of the genus would have facilitated limb reduction and body elongation by furnishing an environment conducive to the adoption of fossorial habit.

The photo shows a Pilbara Flame-tailed Slider orRedtail Lerista, Lerista flammicauda, endemic to West Australia and found only in the Pilbara shrublands and the Western Australian Mulga shrublands.

References: [1] - [2] - [3]

Photo credit: ©Jordan Vos

Locality: The Pilbara, Western Australia

How Evolution Gave Some Fish Their Electric Powers
by Nick Stockton
The electric eel is one of the many creatures Charles Darwin sliced up and examined in his years aboard the H.M.S. Beagle. When he cut it open, he found that 80 percent of the fish’s body was taken up by three organs made of what looked like muscle tissue, but not quite. This is where the animal makes electricity.
After finding similar organs in other fish, Darwin correctly deduced that the lineages—six in all—came to the same adaptive conclusion independent of one another. Until now, though, no one has known how similar they were. According to a paper published today in Science, at least three of the six lineages evolved their electric organs through the same genetic pathways.
Taxonomically, these lineages were too distantly related to have inherited the organ from a common ancestor. In Origin of Species Darwin wrote that “Natural selection, working for the good of each being and taking advantage of analogous variations, has sometimes modified in very nearly the same manner two parts in two organic beings.” Biologists call this convergent evolution…
(read more: Wired Science)
photograph by Jason Gallant

How Evolution Gave Some Fish Their Electric Powers

by Nick Stockton

The electric eel is one of the many creatures Charles Darwin sliced up and examined in his years aboard the H.M.S. Beagle. When he cut it open, he found that 80 percent of the fish’s body was taken up by three organs made of what looked like muscle tissue, but not quite. This is where the animal makes electricity.

After finding similar organs in other fish, Darwin correctly deduced that the lineages—six in all—came to the same adaptive conclusion independent of one another. Until now, though, no one has known how similar they were. According to a paper published today in Science, at least three of the six lineages evolved their electric organs through the same genetic pathways.

Taxonomically, these lineages were too distantly related to have inherited the organ from a common ancestor. In Origin of Species Darwin wrote that “Natural selection, working for the good of each being and taking advantage of analogous variations, has sometimes modified in very nearly the same manner two parts in two organic beings.” Biologists call this convergent evolution…

(read more: Wired Science)

photograph by Jason Gallant

The Improbable—but True—Evolutionary Tale of Flatfishes

by Ferris Jabr

Every summer there’s a snowfall in the sea. Instead of drifting down, it falls up, and rather than flakes of ice, it’s made of innumerable diaphanous eggs that rise from the bottom of the ocean to the surface. There, they hatch into baby flatfish, each no larger than a pinhead.

For the first few weeks of life, they look and act like typical fish fry, swimming upright through sun-dappled waters, darting after plankton. Soon enough, though, these young flatfish lose all semblance of normalcy during one of the most difficult puberties of any animal on the planet.

As a larval flatfish begins its passage into adulthood, it does not merely experience uneven growth spurts and mood swings. Rather, it changes from a cute, symmetrical little fish into a total anatomical disaster…

(read more: Nova Next - PBS)

photos: Jayvee Fernandez/Flickr, NOAA Fisheries West Coast/Flickr, Josh More/Flickr

From Shakespearean sonnets to impassioned speeches to lovers’ whispers, human language is an amazingly rich form of expression, whose evolution has long puzzled scientists.

Now, some researchers propose that human language represents the blending of two different communication systems, those found in songbirds and monkeys. Content-based language may have its roots in monkey alarm calls, while grammar may come from the expressive parts of bird song…

Maybe Birds Can Have It All: Dazzling Colors and Pretty Songs, Too  
by Hugh Powell
A study of one of the world’s largest and most colorful bird families has dispelled a long-held notion, first proposed by Charles Darwin, that animals are limited in their options to evolve showiness. The study—the largest of its kind yet attempted—was published today in the Proceedings of the Royal Society B. The natural world is full of showstoppers—birds with brilliant colors, exaggerated crests and tails, intricate dance routines, or virtuosic singing. But it’s long been thought that these abilities are the result of trade-offs. For a species to excel in one area, it must give up its edge in another. For example, male Northern Cardinals are a dazzling scarlet but sing a fairly simple whistle, whereas the dull brown House Wren sings one of the most complicated songs in nature.
Animals have limited resources, and they have to spend those in order to develop showy plumage or precision singing that help them attract mates and defend territories,” said Nick Mason, the paper’s lead author.  ”So it seems to make sense that you can’t have both. But our study took a more detailed look and suggests that actually, some species can.” Mason did the research as a master’s student at San Diego State University. He is now a Ph.D. student at the Cornell Lab of Ornithology…
(read more: Cornell Lab of Ornithology)
Photos by Peter Wendelken, Frank Shufelt, Keith Bowers, Vivek Tiwari, and Priscilla Burcher

Maybe Birds Can Have It All: Dazzling Colors and Pretty Songs, Too 

by Hugh Powell

A study of one of the world’s largest and most colorful bird families has dispelled a long-held notion, first proposed by Charles Darwin, that animals are limited in their options to evolve showiness. The study—the largest of its kind yet attempted—was published today in the Proceedings of the Royal Society B.

The natural world is full of showstoppers—birds with brilliant colors, exaggerated crests and tails, intricate dance routines, or virtuosic singing. But it’s long been thought that these abilities are the result of trade-offs. For a species to excel in one area, it must give up its edge in another. For example, male Northern Cardinals are a dazzling scarlet but sing a fairly simple whistle, whereas the dull brown House Wren sings one of the most complicated songs in nature.

Animals have limited resources, and they have to spend those in order to develop showy plumage or precision singing that help them attract mates and defend territories,” said Nick Mason, the paper’s lead author.  ”So it seems to make sense that you can’t have both. But our study took a more detailed look and suggests that actually, some species can.” Mason did the research as a master’s student at San Diego State University. He is now a Ph.D. student at the Cornell Lab of Ornithology…

(read more: Cornell Lab of Ornithology)

Photos by Peter Wendelken, Frank Shufelt, Keith Bowers, Vivek Tiwari, and Priscilla Burcher

Australian and American snakes evolved to look alike     

Australian snakes evolved to have similar body forms as North American snakes, but they have quite different diets

by Jacqueline Outred

Australian snakes have evolved the same types of advanced body forms as their counterparts in North America, even though they’ve been on separate continents for millions of years, new research has shown.

"Australia has a death adder, a stout cryptically-coloured ambush predator that looks, for all practical purposes, like a typical [American] viper. But it’s not related to vipers and is much more closely related to other Australian elapid snakes," says Dan Rabosky, evolutionary biologist at the University of Michigan and a co-author on the paper.

Studying the form and structure of a large number of preserved snake specimen, the researcher found that Australian snakes evolved and diversified to fill the same type of roles that different kinds of snakes occupy in North America demonstrating the evolutionary theory of convergence…

(read more: Australian Geographic)

images:

T - The Australian death adder (Acanthophis pyrrhus) is physically similar to vipers in North America. Image Credit: Christopher Watson/Wikimedia

B - The American Chilomeniscus stramineus (l) and the Australian Simoselaps anomalus (r) look similar, but evolved on different continents over millions of years. (Credit: Kate Jackson/Dan Rabosky)

Tetrapod Zoology: Seals, the Early Years

by Darren Naish

It’s the moment you’ve all been waiting for… stem-pinnipeds at Tet Zoo. Or, probable stem-pinnipeds anyway. This minimum-effort post is brought to you on the back of work showing that pinnipeds (seals, sea lions and walruses) are monophyletic, not diphyletic, and that the taxa shown here – Potamotherium, Puijila and so on – really are early members of the pinniped lineage, not convergently pinniped-like carnivorans of some sort. If there are any questions or areas of debate — hey, that’s what the comment section is for.

The illustrations of Semantor are from Orlov (1933). The images of Puijila, and the cladogram shown at the bottom, are from Rybczynski et al. (2009) (the cladogram is arguably odd in showing the name Pinnipedia as being attached to the entire clade rather than just to the crown-group… which isn’t shown on the tree). The skeletal reconstruction of Potamotherium is from Savage & Long (1986) and the life restoration of it is by Graham Allen…

(find out more: Scientific American)

A Long-Ago Ancestor: A Little Fish, With Jaws to Come

Half a billion years ago, a new study suggests, your ancestors may have looked like this…

by Carl Zimmer

This two-inch, 505-million-year-old creature belonged to the lineage that would later produce sharks, eels and other fish — along with birds, reptiles and mammals like us. This early vertebrate, known as Metaspriggina, was something of a mystery for years, known only from a pair of ambiguous fossils. But recently, scientists unearthed a trove of much more complete Metaspriggina fossils.

As they report today in the journal Nature, the new fossils offer a remarkably detailed understanding of the first vertebrates, helping scientists understand how major parts of our own anatomy — from eyes to jaws to our muscles — evolved.

“It’s clearly a benchmark early vertebrate, which we haven’t had before,” said Thurston Lacalli of the University of Victoria in British Columbia, who was not involved in the research.

Discovering the origins of vertebrates has occupied biologists for decades. A few living invertebrates, such as worm-like animals called lancelets, are closely related to vertebrates, but our ancestors split off from theirs more than 600 million years ago…

(read more: NY Times)

image from video by Phlesch Bubble