For an interesting weekend read, from Popular Science: Why are there no native monkeys in North America?
“Primates came to the New World (meaning North and South America) from, we think, Africa. As improbable as it sounds, scientists think early primates crossed the Atlantic Ocean and landed on the shores of both continents tens of millions of years ago, probably on some kind of vegetation raft. That’s how most plants and animals get to isolated islands–which the Americas were, at the time. Fossils have been recovered of early primates in Texas a whopping 43 million years ago, the oldest primate fossil ever found in North America. But the continents looked very different then, compared to now; most importantly, North and South America were completely different islands. The Isthmus of Panama, which we now refer to as Central America, didn’t appear until much later, by which time the climate on both Americas was very different from when the primates first landed there.”
The oldest amber-encased arthropods have been found in a sample of Triassic period amber, dating to about 230 million years ago. Amber is the fossilized remains of tree sap or resin, and in some cases amber contains insects or other matter trapped inside the amber when it was still liquid. Such instances provide very well preserved remains of ancient organisms. Researchers screened around 70,000 tiny droplets of amber recovered from the Dolomite Alps in northern Italy and found three examples of two new species of gall mites. While modern gall mites feed predominantly on flowering plants, the researchers note that as these mites lived before the appearance of flowering plants, they must have fed on the common ferns and conifers of the Triassic period instead. These are the oldest arthropods yet found encased in amber, and the first example dating from the Triassic period.
The research is published in the Proceedings of the National Academy of Sciences: Schmidt et al. Arthropods in amber from the Triassic Period. PNAS. Published online before print August 27, 2012, doi: 10.1073/pnas.1208464109
(American Museum of Natural History)
Image: Am. Mus. Nat. Hist./PNAS
Researchers have uncovered the oldest known modern human fossils from southeast Asia. The team discovered a fragmented human skull in a cave in the Annamite Mountains of Laos, and they have dated the fragments to between 46,000 and 63,000 years of age. University of Illinois anthropologist Laura Shackelford, leader of the team that found the skull, says, “It’s a particularly old modern human fossil and it’s also a particularly old modern human for that region. There are other modern human fossils in China or in Island Southeast Asia that may be around the same age but they either are not well dated or they do not show definitively modern human features. This skull is very well dated and shows very conclusive modern human features.”
The finding is about 30,000-50,000 years older than the next-oldest modern human fossils from the area, pushing the evidence for a human presence there further back in time. Shackleford says that the date also provides fossil evidence in support of genetic studies that place the human presence in southeast Asia back about 60,000 years.
The finding is reported in the Proceedings of the National Academy of Sciences.
(University of Illinois)
Image: University of Illinois/F. Demeter
by Andrew Ratelle
Beneath the scorching heat and wind of a Wyoming summer, a mix of nearly a hundred volunteers and hired hands worked some six thousand man hours between the months of June and July digging for treasure. Hidden within the same land that made cattle farmers rich and oil barons richer lay a find many times rarer, and to some, many times more precious than even the blackest gold.
A nearly complete backbone, fully articulated with the upswept arch of rigor mortis still preserved was found along with an intact pelvis, ribs, and thighbone. They belonged to a Tyrannosaurus rex, one not yet fully grown, but still large enough to have stretched at least fifteen feet from shoulders to hips.
Finds like this are uncommon enough, but more uncommon still is the manner of their preservation. The bones were encased within a sedimentary concretion, a single block of natural concrete made up of the mud and sand that filled in and around the corpse near the time of death and petrified along with the animal’s remains. It’s an exceptionally rare type of process that can produce a natural “mummification” of sorts, preserving any undecayed skin, tendons, muscle, and internal organs along with what’s left of the skeleton. Read more →
Scientists are discussing the implications of a new, good-condition dinosaur skeleton uncovered in Germany. The skeleton, of a juvenile Sciurumimus, appears to be covered with downy feathers. Feathered dinosaurs are nothing new, and finding them in very birdlike dinosaurs is not too surprising, but paleontologists believe that Sciurumimus is more distantly related to birds than any other feathered dinosaurs yet found. Which leads to the question: just how common were feathers in dinosaurs? Among paleontologists, opinions vary, some believing that feathers are found only in the most bird-like species, while others believe that all or nearly all dinosaurs sported feathers or down. Sciurumimus just adds another piece of evidence to the puzzle. Read here from ScienceNews.
I recall that when I first saw Jurassic Park, one of the things that really contributed to the movie was Spielberg’s ability to convey even the non-visual atmosphere of his locations so well. Not only was the animation of the dinosaurs impressive, but by capturing the subtle details, the humid tropical landscape was almost palpable as well, contributing to the prehistorically exotic overall “feeling” of the dinosaur story. A key component of that atmosphere was, of course, sound. Insects, in particular, contribute greatly to the auditory environment of forested locations, and now scientists studying prehistoric insects have now replicated some of the sounds of the ancient Jurassic landscape. By constructing an intricate and precise replica of a Jurassic katydid’s wings, they have been able to reproduce the sound created when the ancient katydids, like their modern counterparts, rub those wings together to signal others of their kind. The researchers found that the ancient insects produced a characteristically low note, one that they suspect was well-adapted to convey the katydid’s songs through the leafy environs of Jurassic jungles. You can hear the replicated sounds in the video above, and read more about this story here.
Thirty millenia ago, in the cold days of the Pleistocene, a ground squirrel buried some seeds in the Siberian ground for storage, as squirrels are wont to do. The squirrel never returned, and those seeds stayed buried through the ages, preserved in the icy permafrost. Now, Russian scientists have recovered the seeds and, 30,000 years after they were produced and buried, grown the seeds into healthy plants.
Read the story here from the BBC.
A scientist with the University of Oregon is painting a new picture of the origin of the first four-legged animals, suggesting that they emerged in wet, swampy woodlands rather than the drying arid areas previously assumed. Scientists had imagined that the emergence of amphibian tetrapods (four-legged animals) from fish occurred amidst a period of drying which forced the proto-limbed fish to leave their ponds in search of new ones. Gregory Retallack points out that the earliest limbed animals would likely not have survived such searches in a hostile environment with only the use of inefficient limbs, and suggests instead that limbs likely developed in a combination water-and-land environment, like a wooded swamp, where early forms of limbs would have helped the first amphibians to move around the obstacles in their environment, moving often from water to land in search of food. Instead of leaving ponds in desperate searches across a dry landscape, he envisions early tetrapods scrambling in and out of watery pools, clambering over roots and rocks and banks in a moist, boggy environment. In this sort of landscape, even rudimentary limbs might be of some help, whereas on totally dry land they would be as good as useless. To bolster his claim, Retallack notes that early transitional forms of tetrapod fossils are found in not in association with drying bodies of water, but rather with flooded, wooded plains. In addition, the earliest forms appeared concurrently with the spread of the first large plants, creating the very first wooded, moist environments in which amphibians thrive. Altogether, then, we have a plausible new picture of the emergence of the first crawling land animals. Read more here.