Hello fellow scientists, writers, countrymen and countrywomen, lend me your years. . .years of experience of enjoyment of both science and writing. Both sides of your brain are . . .well, developed. :-)
Parts of a 2,000-plus-year-old skeleton have been recovered from the shipwreck which contained an early analog computer, the Antikythera Mechanism, which we discussed here at Partial Ellipsis of the Sun in 2014.
Researchers found the skeleton last August during their ongoing excavation of the wreck, which lies on the ocean floor off the Greek island of Antikythera in the Aegean Sea.
“Against all odds, the bones survived over 2,000 years at the bottom of the sea, and they appear to be in fairly good condition,” Dr. Hannes Schroeder, DNA expert, of the Natural History Museum in Copenhagen, Denmark, said.
The discovery consists of a partial skull with three teeth, arm and leg bones, and several parts of ribs as reported yesterday in Nature. They are the first bones to be recovered from the wreck, particularly exciting during this era of DNA sequencing.
The passenger or crew member “was trapped in the ship when it went down and he or she must have been buried very rapidly or the bones would have (been) gone by now.” Some of the bones remain on the seafloor, but others have been brought to the surface for analysis.
If the research team, which is led by experts from Woods Hole, can recover DNA from the skeleton, they may be able to confirm the individual’s gender and hair and eye color, as well as his or her ethnicity and geographic origin.
The wreck, which is believed to be of a Greek trading or cargo ship, is the largest ancient shipwreck ever discovered. Since its discovery by sponge divers in 1900, divers have recovered extraordinary artifacts including glassware, gold jewelry,
marble statues and an ancient weapon known as a "dolphin,"
a lead and iron artifact that weighs about 220 pounds. "Dolphins" were defensive weapons that were dropped from the ship’s yard, a spar on the mast, onto the deck of an attacking ship, such as a pirate vessel.
The Antikythera Mechanism remains the star of the seafloor find, at least so far.
These are the best of (DNA) times. . .
Speaking of times, we are close to the 3-year anniversary of Partial Ellipsis of the Sun on October first!
Our ancestors evolved three times faster in the 10 million years after the extinction of the dinosaurs than in the previous 80 million years, according to University College of London researchers.
The research team found the speed of evolution of placental mammals (a group that today includes about 5000 species including humans) was constant before the extinction event but exploded after, resulting in the varied groups of mammals we see today.
Lead (not lead ;-)) researcher, Dr. Thomas Halliday said: "Our ancestors, the early placental mammals, benefitted from the extinction of non-avian dinosaurs and dwindling numbers of competing groups of mammals. Once the pressure was off, placental mammals suddenly evolved rapidly into new forms."
"In particular, we found a group called Laurasiatheria quickly increased their body size and ecological diversity, setting them on a path that would result in a modern group containing mammals as diverse as bats, cats, rhinos, whales, cows, pangolins, shrews and hedgehogs." Laurasiatheria is a superorder of placental mammals believed to have originated on the northern supercontinent of Laurasia. Thus it was the northern landmasses that produced much of the mammal explosion.
The team found that the last common ancestor for all placental mammals lived in the late Cretaceous period, about three million years before the non-avian dinosaurs became extinct 66 million years ago. This date is about 20 million years younger than suggestions from previous studies which used molecular data from living mammals and assumed a near-constant rate of evolution.
In this study the researchers analysed fossils from the Cretaceous to the present day, and used the dates of their occurrence in the fossil record to estimate the timing of divergences based on an updated tree of life. The new tree was released in 2015 and has the largest representation of Paleocene mammals to date.
The scientists measured all the small changes in the bones and teeth of 904 placental fossils and mapped the anatomical differences between species on the tree of life. From measuring the number of character changes over time for each branch, they found the average rate of evolution for early placental mammals both before and after the dinosaur extinction event. They compared the average rate of evolution over the geological stages before the extinction and the geological stages after to see what impact it had.
Senior author, Professor Anjali Goswami said, "Our findings refute those of other studies which overlooked the fossils of placental mammals present around the last mass extinction. Using rigorous methods, we've successfully tracked the evolution of early placental mammals and reconstructed how it changed over time. While the rate differed between species, we see a clear and massive spike in the rates of evolution right after the dinosaurs become extinct, suggesting our ancestors greatly benefitted from the demise of the dinosaurs. The huge impact of the dinosaur extinction on the evolution of our ancestors really shows how important this event was in shaping the modern world."
Professor Paul Upchurch, co-author of the study, added: "Our large and refined data set allows us to build a clearer picture of evolutionary history. We plan on using it to study other large-scale evolutionary patterns such as how early placental mammals dispersed across the continents via land bridges that no longer exist today."
I'd like to take that land bridge from South America to Africa in the southern land masses of Gondwanaland. How about you? Does "Reunite Gondwanaland!" ring true to you? Steph
