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Monday morning here in Possum Valley and the time has arrived for science talk. New discoveries, new takes on old knowledge, and other bits of news are all available for the perusing in today's information world. Over the fold are selections from the past week from a few of the many excellent science news sites around the world. Today's tidbits include mammalian evolution in North America tracked climate change, ancient seal found in Jerusalem linked to ritual, the perils of 'bite-sized' science, and 'head-first' diversity shown to drive evolution. Pull up that comfy chair and grab a spot near the fireside. There is always plenty of room for everyone. Another session of Dr. Possum's science education, entertainment, and potluck discussion is set to begin.
Featured Stories
Climate change was a distinct and major force in at least six major mammalian evolutionary changes over the course of millions of years in North America.
By the numbers, the research showed correlations between species diversity and temperature change, but qualitatively, it also provided a narrative of how the traits of typical species within each wave made sense given the changes in vegetation that followed changes in climate. For example, after a warming episode about 20 million years in the early Miocene epoch, the dominant vegetation transitioned from woodland to a savannah-like grassland. It is no surprise, therefore, that many of the herbivores that comprised the accompanying “Miocene fauna” had high-crowned teeth that allowed them to eat the foods from those savannah sources.
To the extent that the study helps clarify scientists’ understanding of evolution amid climate changes, it does not do so to the extent that they can make specific predictions about the future, (researcher) Janis said. But it seems all the clearer that climate change has repeatedly had meaningful effect over millions of years.
A rare find in Jerusalem, an ancient seal, is linked to rituals performed in the city 2000 years ago.
...it dates from between the 1st century B.C. to 70 A.D. — the year Roman forces put down a Jewish revolt and destroyed the second of the two biblical temples in Jerusalem.
The find marks the first discovery of a written seal from that period of Jerusalem's history, and appeared to be a unique physical artifact from ritual practice in the Temple.
(snip)
Archaeologists say the seal was likely used by Temple officials approving an object for ritual use — oil, perhaps, or an animal intended for sacrifice. Materials used by Temple priests had to meet stringent purity guidelines stipulated in detail in the Jewish legal text known as the Mishna, which also mention the use of seals as tokens by pilgrims.
The modern pressures of publication leads to many scientists offering shorter papers in larger quantities.
Proponents laud the increased influence authors gain from more citations. Precisely, say the two (researchers)—but two short papers do not equal twice the scientific value of a longer one. Indeed, they might add up to less.
The reason: The smaller the experimental sample the greater the statistical deviations—that is, the greater the inaccuracy of the findings. The results are sometimes flukes, with a bias toward false positives—errors a wider ranging study with multiple experiments, plus replication in the same and in other labs, could correct. Strict word limits, moreover, mean cutting the details about previous research. The new results sound not only surprising but also novel. Write the authors: “A bit of ignorance helps in discovering ‘new’ things.”
Over the course of time evolution has been marked by explosions of diversity. At least two of those radiations were driven by 'head-first' diversity.
...two different adaptive radiations in the fossil record. The first was the explosion of ray-finned fishes after the Hangenberg extinction, an event 360 million years ago that decimated ocean life on Earth. The second group was the acanthomorphs, a group of fish that exhibited a burst in diversity around the time of the end-Cretaceous extinction that ended the age of dinosaurs.
In both datasets, the researchers used a method called geometric morphometrics to quantify differences in features such as body depth, fin position and jaw shape between species. Crucially, (researchers) Sallan and Friedman separated head features from body features in their analysis, to better detect the timing of when each compartment showed a burst of diversity in the record.
The results of the two analyses were in agreement: Diversification in cranial features preceded diversification in body types. Unusual head features such as jaws lined with sharp teeth or blunt teeth for crushing appeared before diverse body shapes on a spectrum from slender and eel-like to broad and disc-shaped.
Other Worthy Stories of the Week
The physics of a touchdown flip
Titan: A wet world not far from Earth Photo diary.
First ever direct measurement of the Earth's rotation
Sensing the deep ocean
New theory for where some fish became four-limbed creatures
Sensational bird discovery in China
Brain glial cells help store memory in addition to being 'glue'
Echoes from Eta Carinae's great eruption
Irikaitz archaeological site host to a 25,000-year-old pendant
Sunlight and bunker oil a fatal combination for Pacific herring
Glowing scorpion exoskeletons may be giant eyes
Pions don't want to decay into faster-than-light neutrinos
New material cools under pressure
For even more science news:
General Science Collectors:
Alpha-Galileo
BBC News Science and Environment
Eureka Science News
LiveScience
New Scientist
PhysOrg.com
SciDev.net
Science/AAAS
Science Alert
Science Centric
Science Daily
Scientific American
Space Daily
Blogs:
A Few Things Ill Considered Techie and Science News
Cantauri Dreams space exploration
Coctail Party Physics Physics with a twist.
Deep Sea News marine biology
Laelaps more vertebrate paleontology
List of Geoscience Blogs
ScienceBlogs
Space Review
Techonology Review
Tetrapod Zoologyvertebrate paleontology
Science Insider
Scientific Blogging.
Space.com
Wired News
Science RSS Feed: Medworm
The Skeptics Guide to the Universe--a combination of hard science and debunking crap
At Daily Kos:
This Week in Science by DarkSyde
Overnight News Digest:Science Saturday by Neon Vincent. OND tech Thursday by rfall.
Pique the Geek by Translator Sunday evenings about 9 Eastern time
All diaries with the DK GreenRoots Tag.
All diaries with the eKos Tag
A More Ancient World by matching mole
Astro Kos
SciTech at Dkos.
Sunday Science Videos by palantir
NASA picture of the day. For more see the NASA image gallery or the Astronomy Picture of the Day Archive
SXP 1062, NASA, Public Domain