Wednesday, July 3, 2024
Prehistoric Pompeii discovered - Most pristine trilobite fossils ever found shake up scientific understanding of the long extinct group
Microtomographic reconstruction of the
head and anterior trunk ("body") limbs of the trilobite Protolenus
(Hupeolenus) in ventral view. Credit: Arnaud Mazurier, IC2MP, Univ. Poitiers
Researchers
have described some of the best-preserved three-dimensional trilobite fossils
ever discovered. The fossils, which are more than 500 million years old, were
collected in the High Atlas of Morocco and are being referred to by scientists
as "Pompeii" trilobites due to their remarkable preservation in ash.
The paper, "Rapid volcanic ash
entombment reveals the 3D anatomy of Cambrian trilobites," was published in the journal, Science.
The trilobites, from the Cambrian
period, have been the subject of research by an international team of
scientists, led by Prof Abderrazak El Albani, a geologist based at University
of Poitiers and originally from Morocco. The team included Dr. Greg Edgecombe,
a paleontologist at the Natural History Museum.
Dr. Greg Edgecombe said, "I've been
studying trilobites for nearly 40 years, but I never felt like I was looking at
live animals as much as I have with these ones. I've seen a lot of soft anatomy
of trilobites, but it's the 3D preservation here that is truly astounding.
"An unexpected outcome of our work is discovering that volcanic ash in shallow marine settings could be a bonanza for exceptional fossil preservation."
Credit: Greg Edgecombe
Due
to their hard, calcified exoskeleton often being well-preserved in the fossil record, trilobites are some of the best studied fossil
marine animals. Over 20,000 species have been described by paleontologists over
the past two centuries.
However, until now, comprehensive scientific understanding of this phenomenally diverse group has been limited by the relative scarcity of soft tissue preservation. Owing to the fact the Moroccan trilobites were encased in hot ash in sea water, their bodies fossilized very quickly as the ash transformed to rock—meeting a similar end to the inhabitants of Pompeii following the eruption of Mount Vesuvius.
Artistic reconstruction of two species
of trilobite an instant before burial in a flow of volcanic ash 510 million
years ago. Credit: Prof. A. El Albani, Univ. Poitiers.
The
ash molds preserved each segment of their bodies, their legs and even the
hair-like structures that ran along the appendages. The trilobites' digestive
tract was also preserved after it filled with ash. Even small "lamp
shells" attached to the trilobites' exoskeleton remained attached by
fleshy stalks as they were in life.
Lead author, Prof Abderrazak El Albani,
says, "As a scientist who has worked on fossils from different ages and
locations, discovering fossils in such a remarkable state of preservation
within a volcanic setting was a profoundly exhilarating experience for me.
"I think pyroclastic deposits
should become new targets for study, given their exceptional potential for
trapping and preserving biological remains, including delicate soft tissues.
"These findings are anticipated to lead to significant discoveries about the evolution of life on our planet Earth."
Microtomographic reconstruction of the
trilobite Gigoutella mauretanica in ventral view. Credit: Arnaud Mazurier,
IC2MP, Univ. Poitiers.jp
Using
CT scanning and computer modeling of virtual X-ray slices, the researchers
discovered that appendages found at the edge of the mouth had curved spoon-like
bases but were so small they had gone undetected in less perfectly preserved
fossils.
In fact, it had previously been thought
that trilobites had three pairs of head appendages behind their long antennae
but both Moroccan species in this study showed that there were four pairs.
A fleshy lobe covering the mouth, called
a labrum, was documented for the first time in trilobites.
Co-author Harry Berks, from the University of Bristol, added, "The results revealed in exquisite detail a clustering of specialized leg pairs around the mouth, giving us a clearer picture of how trilobites fed. The head and body appendages were found to have an inward-facing battery of dense spines, like those of today's horseshoe crabs."
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Tuesday, July 2, 2024
July’s Night Sky Notes: A Hero, a Crown, and Possibly a Nova! - UNIVERSE
Like shiny
flakes sparkling in a snow globe, over 100,000 stars whirl within the globular
cluster M13, one of the brightest star clusters visible from the Northern
Hemisphere. Located 25,000 light-years from Earth with an apparent magnitude of
5.8, this glittering metropolis of stars in the constellation Hercules can be
spotted with a pair of binoculars most easily in July. Credits: NASA
High in
the summer sky, the constellation Hercules acts as a centerpiece for late-night
stargazers. At the center of Hercules is the “Keystone,” a near-perfect square
shape between the bright stars Vega and Arcturus that is easy to recognize and
can serve as a guidepost for some amazing sights. While not the brightest
stars, the shape of the hero’s torso, like a smaller Orion, is nearly directly
overhead after sunset. Along the edge of this square, you can find a most
magnificent jewel - the Great Globular Cluster of Hercules, also known as Messier 13.
Look up after sunset during summer months to find
Hercules! Scan between Vega and Arcturus, near the distinct pattern of Corona
Borealis. Once you find its stars, use binoculars or a telescope to hunt down
the globular clusters M13 (and a smaller globular cluster M92). If you enjoy
your views of these globular clusters, you’re in luck - look for another great
globular, M3, near the constellation Boötes.
Globular clusters are a tight ball of
very old stars, closer together than stars near us. These clusters orbit the
center of our Milky Way like tight swarms of bees. One of the most famous short
stories, Nightfall by Isaac Asimov, imagines a civilization living on a planet within
one of these star clusters. They are surrounded by so many stars so near that
it is always daytime except for once every millennium, when a special alignment
(including a solar eclipse) occurs, plunging their planet into darkness
momentarily. The sudden night reveals so many stars that it drives the
inhabitants mad.
Back here on our home planet Earth, we are lucky enough to experience skies full of stars, a beautiful Moon,
and regular eclipses. On a clear night this summer, take time to look up into the Keystone
of Hercules and follow this sky chart to the Great Globular Cluster of
Hercules. A pair of binoculars will show a faint, fuzzy patch, while a small
telescope will resolve some of the stars in this globular cluster.
A red giant star and white dwarf orbit each other in
this animation of a nova similar to T Coronae Borealis. The red giant is a
large sphere in shades of red, orange, and white, with the side facing the
white dwarf the lightest shades. The white dwarf is hidden in a bright glow of
white and yellows, which represent an accretion disk around the star. A stream
of material, shown as a diffuse cloud of red, flows from the red giant to the
white dwarf. When the red giant moves behind the white dwarf, a nova explosion
on the white dwarf ignites, creating a ball of ejected nova material shown in
pale orange. After the fog of material clears, a small white spot remains,
indicating that the white dwarf has survived the explosion. NASA/Goddard
Space Flight Center
Bonus! Between Hercules and the ice-cream-cone-shaped Boötes constellation,
you’ll find the small constellation Corona Borealis, shaped like the letter
“C.” Astronomers around the world are watching T Coronae Borealis, also known
as the “Blaze Star” in this constellation closely because it is predicted
to go nova sometime this summer.
There are only 5 known nova stars in the whole galaxy. It is a rare observable
event and you can take part in the fun! The Astronomical League has issued a Special
Observing Challenge that anyone can participate in. Just make a sketch of the
constellation now (you won’t be able to see the nova) and then make another
sketch once it goes nova.
Tune into our mid-month article on the Night Sky Network page, as we prepare for the Perseids! Keep looking up!
by Vivan
White of the Astronomical Society of the Pacific
Source: July’s Night Sky Notes: A Hero, a Crown, and Possibly a Nova! - NASA Science
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