Scientific Reports, can be found online here]]>
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Scientific Reports, the new study suggests that something seemingly as trivial as hair, more specifically whiskers, allowed mammal like reptiles to outlive their ferocious competitors in the jungle. Dr Julien Benoit and his colleagues from the University of the Witwatersrand, Professors Paul Manger and Bruce Rubidge, studied the fossils of mammal like reptiles, known as therapsids, unearthed in the Karoo of South Africa. They found evidence that leads them to believe the therapsids may have evolved whiskers as a means to operate nocturnally during the Mesozoic Age, well before the ascendancy of the dinosaurs. “Whiskers are an amazing sensory tool to have when you are nocturnal and the evolution of whiskers possibly assisted in the survival of the therapsids – and more specifically the probainognathians – which eventually evolved into mammals as we know them today,” explained Dr. Benoit, in a press release from the University of Witwatersrand. An order of Triassic and Permian period reptiles, therapsids are widely considered the predecessors to modern mammals. It has long baffled scientists how this group of creatures were able to survive not only the competition from the dinosaurs, but also the mass extinction events that wiped out most dinosaur species. A rich fossil record exists of the therapsids, providing insight into their key role in the development of modern mammals. However, until now there was no evidence of hair among therapsids, meaning it was a development believed limited to mammals. Benoit’s team used a unique approach to solve the issue. Instead of looking for fossilised evidence of hair, they deployed scanning technology to search for the neural structures which could have allowed hair to develop in therapsids. Through computerised X-ray micro-tomography (CT scan) and digital three-dimensional modelling, Benoit discovered that therapsids had a shorter maxillary canal, a bony tube in the snout of the animal that houses the trigeminal nerve, than reptiles. The trigeminal nerve is responsible for motor functions in the face. Shortening of the maxillary canal allows for the movement of the trigeminal nerve, letting it extend into the soft tissue of the lips and nose where it innervates a creature’s whiskers. “This leaves the trigeminal nerve free to follow the movements of a flexible snout.” explained Benoit. “In reptiles this canal is long and the nerve is enclosed in the maxilla all along its length, which prevents any movement of the nose and lips,” The team’s research suggests that a mobile snout evolved between 240-246 millions years ago in the Prozostrodontia, a group of dog like therapsids which were direct ancestors of modern mammals. Research carried out on mutant mice suggests that two mammalian features, the cerebellum and the trigeminal nerve, were controlled by the same gene: MSX2. This is the gene that regulates the development of mammary glands and body hairs. As Benoit explained, “This is the gene that makes us mammals”. It seems, based on the team’s CT studies of probainognathians, the group to which Prozostrodontians belong, that MSX2 underwent a significant change in its expression 240-246 million years ago. This could have triggered the evolution of a host of mammalian traits, including hair and whiskers, an enlarged cerebellum, complete ossification of the skull roof, and more importantly, the mammary glands. Developing whiskers would have allowed therapsids to operate in the jungle at night, providing them a key advantage over dinosaurs. The animals may have been afforded the opportunity to hunt without coming into contact with their dangerous rivals. “Our research has shown that these features of mammals were already present in advanced therapsids, prior to the appearance of mammals,” says Benoit. “It also has implications for understanding how mammals survived the domination of dinosaurs during the Mesozoic period and the subsequent evolutionary success of mammals.” For more information: ww.nature.com Image courtesy of Wits University ]]>
Culture24 UK, Wessex Archaeology has just published the full results of their research into these newest discoveries. Neil Fitzpatrick, a representative from the organization, told the website that based on their findings, this site is officially the largest Saxon cemetery discovered in Wiltshire to date – something Fitzpatrick characterized as “pretty cool”, in his own words. There were several noteworthy features discovered regarding the cemetery, most striking of which was how each burial seems to include grave goods including an iron knife. Fitzpatrick remarked that the team was unsure of the symbolism of such an inclusion, but he pointed out that the cultural significance would have been high, as even a large number of burials featuring small children or infants had iron knives as well. There were other discoveries as well, such as nearly a full ten cremations and several warrior burials complete with varied spearheads and shield bosses. One such grave, according to Fitzpatrick, was located beneath an inhumation that had been bereft of grave goods; the warrior himself had been laid to rest with a sword that was in remarkably good condition. Meanwhile, another unique characteristic of the cemetery includes several crouched burials, which tended to either include just an iron knife or no grave goods whatsoever. When it came to the final resting place for women, the graves of female Saxons tended to have recycled Roman-style beads. Broaches of Germanic design festooned with spiral decorations were also common, especially in graves in one area of the cemetery running east to west that may date to the late Iron Age. Thanks to the wide variety of graves in the cemetery, and the several centuries’ worth of burials, Fitzpatrick remarked that it was easy to identify the change from earlier Saxon burials to later Roman ones. The former are much more likely to feature pagan iconography, while the Christian influences of the later Roman period are more prevalent in graves from that era. The Wessex Archaeology representative also pointed out that several funerary structures were found at the cemetery site. Much in the same way that modern cemeteries often feature small mausoleum structures, it seemed common to have similar structures at this cemetery – though they mostly consisted of four posts holding up a roof instead of an enclosed structure. The research findings are available here Image courtesy of Wikimedia Commons user: Pasicles]]>
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Cell Press, adding, “We’ve been working for a long time to understand the fundamental mechanisms behind rod and cone development.” Previous work completed by Swaroop and his team has shown that NRL, a transcription factor, drives retinal cells towards maturing into rods. NRL accomplishes this by suppressing certain genes involved in the development of cone cells, leading researchers to wonder if the shorter wave-length cone cells were changed into rods during the evolution process. To determine the origin of these rods, Swaroop’s team examined the cone cells and rods in mice, taken at various stages of development. The details involved in the embryonic development of an organism frequently reveals traits its evolutionary ancestors carried, like how, for instance, human embryos will initially develop a tail and gill-like slits. What they found was that two days after they were born, the still-developing rod cells had genes typically expressed in cell cones, however, once the mice were ten days old these aspects had become repressed by DNA methylations and histone. When examining zebrafish, which are cone-dominated and diurnal (active during the daytime), the experiments indicated the rod cells didn’t look like cell cones at all. To determine when the elements, which turn cone cells to rod cells, may have originated, the researchers examined the genomic sequences from a number of vertebrate animals. What the team discovered was that as the modern retina developed, the genes which are responsible for NRL regulation became more refined in placental mammals but were lost in a number of non-mammalian groups. The origin of this system seemed to coincide with the evolution of nocturnal adaptations in early mammals. The team then concluded that for mammals, NRL became restricted to the photoreceptors found in the eye, forcing these cells to convert to rods from cones, thereby giving early mammals the needed edge to adapt to an active nocturnal lifestyle. In contrast, humans depend primarily on cone cells for our vision, because our ancestors evolved to take advantage of daylight hours once again The study has been published in the online journal Cell Press. ]]>
Live Science, archaeologist Damian Evans from the École française d’Extrême-Orient published the team’s findings recently, describing how low-flying helicopters were used in conjunction with laser scanning equipment in order to see beyond the Cambodian jungle’s thick foliage. The scans laid bare the dome fields as well as the telltale marks left from buildings that had once been constructed from organic materials and since decayed, Evans explained. More than 735 square miles of Cambodia were scanned by air, with the activity largely taking place during 2015. The revelations included more data about Mahendraparvata, an ancient Cambodian city that would have flourished more than a millennium ago as the Khmer Empire that once ruled much of southeast Asia rose to ascendancy. An initial scan in 2012, one that covered 140 square miles of jungle, had previously revealed a portion of the ancient city. The Khmer Empire is thought to have peaked during the twelfth and thirteenth centuries CE, with its center at the city of Angkor – the site of Angkor Wat today. However, Evans noted in the research paper that the conventional beginning of the classical Angkorian period is closely associated with Mahendraparvata, which is dated to the eighth to ninth century CE, located somewhat north of Angkor. Evans and the rest of the research team are still hard at work trying to determine the size of Mahendraparvata. However, even as they do so, evidence of archaeological topography from the Angkor period, otherwise known as the shape of the ground, seems to indicate human presence in a rough swath of around 15 to 20 square miles. Much of that region was filled with the dome fields arranged in their grid pattern. Ground excavations into these mounds have been relatively fruitless in yielding new information, however, leaving the purpose of these dome fields a mystery to researchers. The domes set out in geometric patterns have proven to be equally enigmatic according to Evans, despite how obvious it is that they were laid down in these shapes deliberately. The research paper, which was published in the Journal of Archaeological Science, is available online Image courtesy of Wikimedia Commons user Clay Gilliland ]]>