stasis

From ScienceDaily: For several decades, scientists have placed polypterids down near the base of the family tree of ray-finned fish, a large group believed to have originated around 385 million years ago. But a new study that used CT scans to probe three-dimensionally preserved fossil fish skulls shakes up the fish family tree by concluding that the emergence of polypterids occurred much later than researchers had thought. The findings also suggest that the origin of all modern ray-finned fish may have occurred tens of millions of years later than is generally believed. … Ray-finned fish represent about half of all backboned animals on Earth. For every species of mammal, bird, reptile and amphibian on land, there is a species of Read More ›

From ScienceDaily: Symbiotic relationships, which involve two different kinds of organism interacting with close physical contact, are common in nature. However, few prehistoric examples involve soft-bodied animals because they are normally not fossilized. Although fossils of the two species of marine worm, Cricocosmia jinnigensis and Mafangscolex sinensi, have been found before, these are the first reported examples to show other animals attached to them. The smaller worm-like guests, a new species named Inquicus fellatus, are up to 3mm long and attached at their bottom ends to the stiff skin of their hosts, with their feeding ends pointing away. espite the fact that Inquicus fellatus are attached to their host worms, there is little indication they were feeding by penetrating the Read More ›

As Stephanie Pappas writes, it’s much more complex than we might think: In 2013, researchers from the Integrated Ocean Drilling Program reported at the annual Goldschmidt Conference in Italy that they’d found microbes in 100-million-year-old sediments in the floor of the deep sea, according to the BBC. The microbes were reproducing once every 10,000 years, such a slow rate that scientists weren’t sure if they could really call the microbes “alive.” More. But surely that is a technicality. If they reproduced at all, they are alive. The issues she raises around very old organisms that have remained extant through cloning may be more meaty. We are getting somewhere if we can determine that something is definitely alive without necessarily coming Read More ›

From ScienceDaily: Mammalian perineal structure derived from septation of the cloaca is an important evolutionary innovation that allows myriad anatomical configurations, diverse reproductive strategies, and precise excretory control available only to mammals. The researchers were surprised to discover that, despite the perineum’s structural complexity, the muscles of the mammalian perineum show a reemergence of a simple pattern of body wall layering that dates back more than 360 million years ago — during the origin of tetrapods, the first vertebrates to move out of the water onto land. [color emphasis added] Basal vertebrates, such as fish, organize their body wall into two muscular layers that are important for swimming. However, with the transition from water to land, the body wall of Read More ›

From ScienceDaily: Researchers have described a new species of brittle star, which are closely related to starfish, and showed how these sea creatures evolved in response to the rise of shell-crushing predators during the late Palaeozoic Era. The results, reported in the Journal of Systematic Palaeontology, also suggest that brittle stars evolved new traits before the largest mass extinction event in Earth’s history, and not after, as was the case with many other forms of life. A fossilised ‘meadow’ of dancing brittle stars — frozen in time in the very spot that they lived — was found in Western Australia and dates from 275 million years ago. It contains several remarkably preserved ‘archaic’ brittle stars, a newly-described genus and species Read More ›

Archaea are thought to be about 3.8 billion years old. From ScienceDaily: By studying the 3-D structure of proteins bound to DNA in microbes called archaea, researchers have turned up surprising similarities to DNA packing in more complicated organisms. “If you look at the nitty gritty, it’s identical,” says Howard Hughes Medical Institute Investigator Karolin Luger, a structural biologist and biochemist at the University of Colorado Boulder. “It just blows my mind.” The archaeal DNA folding, reported August 10 in Science, hints at the evolutionary origins of genome folding, a process that involves bending DNA and one that is remarkably conserved across all eukaryotes (organisms that have a defined nucleus surrounded by a membrane). Like Eukarya and Bacteria, Archaea represents Read More ›

From ScienceDaily: He’s Australian, around half a centimetre long, fairly nondescript, 300 million years old, and he’s currently causing astonishment among both entomologists and palaeontologists. The discovery of a beetle from the late Permian period, when even the dinosaurs had not yet appeared on the scene, is throwing a completely new light on the earliest developments in this group of insects. … “Beetles, which with nearly 400,000 described species today make up almost one-third of all known organisms, still lived a rather shadowy and cryptic existence in the Permian period,” explains Jena zoologist Beutel. “The fossils known to date have all belonged to an ancestral beetle lineage, with species preferring narrow spaces under bark of coniferous trees. They exhibit a Read More ›

From Will Sullivan at PBS Nova Next: While the single-celled organisms that dominated early Earth’s oceans didn’t have much need for teeth, they did find some evolutionary advantage in making their own minerals. According to research published last week, life has been making its own hard parts for at least 810 million years, about 200 million years longer than previously thought. It’s the first occurrence of what scientists call biomineralization, and it could give us deeper insight into both the evolution of living things and Earth’s early climate. More. It also reduces the time for purely Darwinian evolution to work. See also: Stasis: Life goes on but evolution does not happen

Forwarded by reader, from Journal of Paleontology, 2012: —Tympanal ears in insects are important for both intraspecific communication and for the detection of nocturnal predators. Ears are thought, based on modern forms, to have originated independently multiple times within insects and can be found on multiple regions of the body. Here we describe and document the exceptionally well preserved tympanal ears found in crickets and katydids from the Eocene Green River Formation of Colorado, which are virtually identical to those seen in modern representatives of these groups. These specimens are among the best preserved insect ears in the fossil record and establish the presence of ears in two major clades of Orthoptera 50 million years ago. Also discussed and evaluated Read More ›

From ScienceDaily: The origin of animals was one of the most important events in the history of Earth. Beautifully preserved fossil embryos suggest that our oldest ancestors might have existed a little more than half a billion years ago. … However, using a recently developed relaxed molecular clock method called RelTime, a team of scientists at Oakland (Michigan) and Temple (Philadelphia) dated the origin of animals at approximately 1.2 billion years ago reviving the debate on the age of the animals. Puzzled by the results of the American team, researchers from the University of Bristol and Queen Mary University of London decided to take a closer look at RelTime and found that it failed to relax the clock. Their findings Read More ›

From ScienceDaily: Bones are composites of protein fibers, collagen, and a biomaterial, hydroxyapatite. The more orderly the arrangement of the collagen fibers, the more stable the bone, but the more slowly it normally grows as well. The bones of mammals thus have a special structure. This allows them to grow quickly and yet remain stable. “We call this bone form fibrolamellar,” says the paleontologist. Together with his PhD student Christen D. Shelton (now at the University of Cape Town), the scientist looked at humerus bones and femurs from a long-extinct land animal: the mammal predecessor Ophiacodon. This lived 300 million years ago. “Even in Ophiacodon, the bones grew as fibrolamellar bones,” says Sander to summarize the analysis results. “This indicates Read More ›

From ScienceDaily: The Garden of the Ediacaran was a period in the ancient past when Earth’s shallow seas were populated with a bewildering variety of enigmatic, soft-bodied creatures. Scientists have pictured it as a tranquil, almost idyllic interlude that lasted from 635 to 540 million years ago. But a new interdisciplinary study suggests that the organisms living at the time may have been much more dynamic than experts have thought. Scientists have found It extremely difficult to fit these Precambrian species into the tree of life. That is because they lived in a time before organisms developed the ability to make shells or bones. As a result, they didn’t leave much fossil evidence of their existence behind, and even less Read More ›

Over half a billion years earlier than dates usually given. From ScienceDaily: The researchers studied exceptionally well-preserved deposits which are approximately 3.5 billion years old in the ancient Dresser Formation in the Pilbara Craton of Western Australia. They interpreted the deposits were formed on land, not in the ocean, by identifying the presence of geyserite – a mineral deposit formed from near boiling-temperature, silica-rich, fluids that is only found in a terrestrial hot spring environment. Previously, the oldest known geyserite had been identified from rocks about 400 million years old. Within the Pilbara hotspring deposits, the researchers also discovered stromatolites – layered rock structures created by communities of ancient microbes. And there were other signs of early life in the Read More ›

From ScienceDaily Paleontologists have uncovered a new fossil species that sheds light on the origin of mandibulates, the most abundant and diverse group of organisms on Earth, to which belong familiar animals such as flies, ants, crayfish and centipedes. Named Tokummia katalepsis by the researchers, the creature documents for the first time the anatomy of early mandibulates, a sub-group of arthropods with specialized appendages known as mandibles, used to grasp, crush and cut their food. … “The pincers of Tokummia are large, yet also delicate and complex, reminding us of the shape of a can opener, with their couple of terminal teeth on one claw, and the other claw being curved towards them,” said Aria. “But we think they might Read More ›

From ScienceDaily: The new specimen from the rich Early Cretaceous Jehol Biota (approximately 131 to 120 million years old) is referred to as Eoconfuciusornis, the oldest and most primitive member of the Confuciusornithiformes, a group of early birds characterized by the first occurrence of an avian beak. Its younger relative Confuciusornis is known from thousands of specimens but this is only the second specimen of Eoconfuciusornis found. This species comes only from the 130.7 Ma Huajiying Formation deposits in Hebei, which preserves the second oldest known fossil birds. Birds from this layer are very rare. This new specimen of Eoconfuciusornis, housed in the Shandong Tianyu Museum of Nature, in Eastern China, is a female. The ovary reveals developing yolks that Read More ›