Three-Billion-Year-Old Plankton Found in Australia

9 06 2013

The Farrel Quartzite formation in Western Australia has yielded a group of both spheroid and spindle-like microfossils believed to be planktonic organisms.

At 3 billion years old, they are some of the oldest fossils ever found.  According to a study in the June issue of the journal Geology, the fossils seem to be similar to ones found in Strelley Pool Formation also in Australia and the Onverwacht Group of South Africa, both of which are approximately 3.4 billion years old.

A team of American and Japanese scientists have identified the fossils as being of biogenic origins (i.e., having once been alive or created as the result of living processes) based on analysis of their stable carbon isotopes.  The results also show that the structures found are actual fossils and not “pseudofossils”, created when the environment physically reprocesses organic material already existing in the sediment.

In addition, the information provided by the analysis of the fossils indicates that they were likely autotropic, which means that they made their own food (e.g., many plants currently living make their own food through photosynthesis).

The report points out that if this interpretation of the fossils is correct, then they represent the remains of a “cosmopolitan” biological community “that lasted several hundred million years, starting in the Paleoarchean”.  The Paleoarchean was a geologic era that lasted from about 3.6 to about 3.2 billion years ago.

The original article can be found here:
http://geology.gsapubs.org/content/41/6/651.abstract

An excellent summary article (along with a photo of one of the fossils) can be found at Sci-News.com here:
http://www.sci-news.com/paleontology/article01136-plankton-microfossils-australia.html

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Whence Brontosaurus?

22 03 2012

Paleontologists, like everyone else, make their share of mistakes.  Unfortunately, paleontological mistakes become incorporated into scientific literature and sometimes (as in this case) also into the collective consciousness of the general public, reverberating through decades and centuries, long after they are left behind by the science that spawned them.

Such is the case with Brontosaurus.  Long the icon of the dinosaur world, this genus of herbivorous sauropods whose name means “thunder lizard” was a mistake.  An Apatosaurus that had an inaccurate reconstruction of its head added to the original display (because the specimen being used was missing its head when it was discovered), it now exists in science only as a casebook example of phylogenetic inference run amok.  It is also a casebook example both of how we sometimes let our prejudices guide our decisions and how scientific competition is not always a good thing.

The original specimen, still in the great hall of the Peabody Museum of Natural History, at Yale University, in New Haven, Connecticut (USA), went on display in 1905, some six years after Marsh’s death.  It remains in its original pose, based on the early twentieth belief that the animal walked with its head drooping and its tail dragging the ground behind it.  It has, however, had its head replaced with the correct one for the species.  By contrast, the specimen in the American Museum of Natural History shows what is referred to as the “modern posture”, with  its head sticking forward just higher than its body and its tail raised to body level, to demonstrate how scientists currently believe the animal actually looked in life.

Apatosaurus excelsus formerly Brontosaurus excelsus

The original conception of how Brontosaurus excelsus, now Apatosaurus excelsus looked, with its head drooping and its tail being dragged behind.
Image Credit: Image is from Wikipedia Commons and is in the public domain.

So, how did all of this happen?  The story goes something like this… From the late 1860s onward, two American paleontologists, Othniel Charles Marsh and Edward Drinker Cope were engaged in an open feud over the discovery of dinosaur fossils in the American West.  The feud began “back east” as they use to say in the West, when Cope accused Marsh of paying quarrymen in New Jersey to divert to himself fossils that had been paid for by and promised to Cope.  Soon, the two men were engaged snipping at each other’s fossil finds, feuding over fossil hunting rights in the western territories, and in general name calling and accusations.  They tried to out-do each other by finding and naming the largest number of fossils and the biggest specimens they could find.

In the midst of this feud, in 1879, Marsh discovered a very large specimen of a sauropod dinosaur at Como Bluff, in southeastern Wyoming (USA).  It was larger and much more complete than anything that had been found up to then, but it had one little problem.  It was missing its head.  Marsh was convinced that it was an entirely new genus and species, which he named Brontosaurus excelsus. The species name (excelsus) means “highest or sublime” and is intended to refer to the fact that it had the greatest number of sacral vertebrae of any sauropod known at the time.

Scientists started preparing the specimen for display.  Missing bones were replaced using known examples from close relatives of Brontosaurus.  The specimen was missing its feet, so sauropod feet that had been found at the same quarry were used.  But, the head was still a problem.  What to do?  What would the head of such a beast look like?  Marsh, being a thorough nineteenth century man, dismissed many of the proposal as being too effete for such a large animal.  Surely its head would be robust, virile (one at the time might have been tempted to say manly).  So, Marsh had a head constructed from bones of similar species that looked the way Marsh thought Brontosaurus‘ head should look.  This composite skull (which we now know to be mostly made of Brachiosaur bones) was duly created and fitted to the mounted skeleton.  Thus, it was not the (relatively) delicate skull of Apatosaurus excelsus, that would eventually be deemed to be the true appearance of the creature.

Othniel Charles (O.C.) Marsh

Othniel Charles (O.C.) Marsh, who found and named Brontosaurus.
Image Credits: Image is from Wikipedia Commons and is in the public domain.

Marsh, who died in 1899, never lived to see his specimen on display.  Cope had already died in 1897, and their great feud, now known as the Bone War, had died with them.

When it went on display, Brontosaurus was the first sauropod to be seen by the public, and it created a sensation.  It captured the public’s imagination and became a cultural icon of the science of paleontology.  And there it remained through most of the twentieth century, captured in a million images ranging from hollywood renditions in movies to corporate images for oil companies, to a thousand and one cartoon creations and magazine images.

But, even before Brontosaurus went on display, its name and identity were being challenged.  In 1903, paleontologist Elmer Riggs took another look at the fossils.  He agreed with Marsh that B. excelsus was likely its own species, but decided that it had too much in common with Apatosaurus to be a distinct genus.  Riggs reclassified the specimen as Apatosaurus excelsus, where it has remained to this day.  Most scientists over the years have agreed with him.  Yet, in the eyes of the public, it was always Brontosaurus.

Why, you might ask, didn’t Riggs reclassify Apatosaurus into Brontosaurus, since the latter was clearly the better known and more popular name?  The reason for that is the rules surrounding the naming and renaming of animals in biology.  This is governed by rules set down by the International Commission on Zoological Nomenclature (ICZN).  According to those rules, if two genera are determined to be the same, then the one that was named first has priority and the animal(s) in the one named later are reclassified into the older one.  It should be noted here that the same rule applies at all levels of scientific nomenclature (family, genera, species, etc.).  Since Apatosaurus had been named in 1877 (ironically by Marsh himself), Apatosaurus won, and Brontosaurus became what is known as a “junior synonym” and was discarded from formal use.

It might have remained that way, with the general public knowing Brontosaurus and scientists knowing Apatosaurus, but for the U.S. Postal Service.  In 1989, they issues a series of four dinosaur stamps, one of which was of Brontosaurus.  A number of paleontologists went ballistic, accusing the post office of promoting inaccurate science.  From that hoopla, the general public first became aware of the whole Brontosaurus fiasco and the fact that their “beloved” Brontosaurus was actually something else.  In the eyes of some in the public, it called into question the reputation that paleontologists had worked so hard to established.  It seemed that the Bone War had done more harm to paleontology, nearly a century after it had ended.

Others point out that it has shown paleontology as a science that learns from its mistakes and is honest and strong enough to make the necessary changes and go on.

In any case, it certainly shows that men of science can have their own issues.  Aside from the rivalry between Cope and Marsh, it shows how we are slaves to our times.  Marsh could not see that his fossil’s head was smaller and more delicate than the burly version he envisioned, largely because his society said it was supposed to be that way.

It also demonstrates the nineteenth century European fascination with naming and categorizing things, often to the exclusion of anything else, especially if that something else disagreed with the way they thought things should be.

Alas, we have our own prejudices.  Will we be able to stand the scrutiny of our successors a hundred years from now?  Only time will tell, but in any event, Brontosaurus was the dinosaur that never was, except in our own imaginations.





Findings Provide Strongest Link Yet to Volcanically-Associated Cause for End-Permian Mass Extinction

24 03 2010
This image was created by Kiff and is courtesy of Wikimedia Commons.  It is licensed under the GNU Free Documentation License.

Pangea as scientists believe it appeared at the end of the Permian Period

Research results published Monday in the online journal Proceedings of the National Academy of Sciences (PNAS) provides the strongest association between the mass extinction that occurred at the end of the Permian period and volcanic eruptions (specifically those occurring along the east coast of the United States during the beginning of the breakup of Pangea.

 The authors were Jessica H. Whiteside, Paul E. Olsen, Timothy Eglinton, Michael E. Brookfield, and Raymond N. Sambrotto.

 Following is the abstract for the article

 Abstract

A leading hypothesis explaining Phanerozoic mass extinctions and associated carbon isotopic anomalies is the emission of greenhouse, other gases, and aerosols caused by eruptions of continental flood basalt provinces. However, the necessary serial relationship between these eruptions, isotopic excursions, and extinctions has never been tested in geological sections preserving all three records. The end-Triassic extinction (ETE) at 201.4 Ma is among the largest of these extinctions and is tied to a large negative carbon isotope excursion, reflecting perturbations of the carbon cycle including a transient increase in CO. The cause of the ETE has been inferred to be the eruption of the giant Central Atlantic magmatic province (CAMP). Here, we show that carbon isotopes of leaf wax derived lipids (-alkanes), wood, and total organic carbon from two orbitally paced lacustrine sections interbedded with the CAMP in eastern North America show similar excursions to those seen in the mostly marine St. Audrie’s Bay section in England. Based on these results, the ETE began synchronously in marine and terrestrial environments slightly before the oldest basalts in eastern North America but simultaneous with the eruption of the oldest flows in Morocco, a CO super greenhouse, and marine biocalcification crisis. Because the temporal relationship between CAMP eruptions, mass extinction, and the carbon isotopic excursions are shown in the same place, this is the strongest case for a volcanic cause of a mass extinction to date.

For more information, please see the original PNAS journal article at the following URL:
http://www.pnas.org/content/early/2010/03/15/1001706107.full.pdf+html?sid=9cdfecda-f033-4211-958c-db9fdb86a405.

This image is in the public domain because it contains material originally created by the U.S. Geological Survey.

This animation shows the breakup of Pangea, that began at the end of the Permian Period. Volcanic Activity associated with this breakup (particularly in Siberia and the US east coast) is believed to have triggered the largest mass extinction in earth's history.





Major Find of Early Sauropod in Southern Utah

23 03 2010
This image is licensed under the Creative Commons Attribution License (CCAL), held by the authors of the original journal article (Joseph J. W. Sertich and Mark A. Loewen)

Seitaad ruessi, showing the parts of the skeleton found (light parts)

An important new species of prosauropod has been found in southern Utah.  While numerous and widespread in other parts of the world, this type of dinosaur is a rare find in North America.

Described in an article by Joseph J. W. Sertich and Mark A. Loewen, appearing on March 24, in the online journal PLoS One, the new species, named Seitaad ruessi, was an early ancestor of the sauropod dinosaurs.  It lived approximately 185 million years ago (during the lower Jurassic) and was approximately 10-to-15 feet long and 3-to-4 feet high.  Like most other prosauropods, S. ruessi was likely a herbivore.  It walked on its hind legs, with its front ones used for grasping.

While only the central portion of the skeleton was found, it none-the-less constitutes one of the most complete prosauropods found North America.

Prosauropods lived in the late Triassic and early Jurassic periods, eventually giving rise to the large sauropods that are so well known from the later Jurassic and Cretaceous periods.  They were widespread globally, specimens having been found throughout much of the world, though finds in North America have been scarce.  According to the journal article, prior to this find, only one taxon from eastern North America and several “fragmentary specimens” from the western part of the continent were known.

The scientists concluded that S. ruessi was “closely related to plateosaurid or massospondylid” and that “its presence in western North America is not unexpected for a member of this highly cosmopolitan clade.”

The find came to light in 2004, when an artist stumbled across it while studying rock paintings.  Scientists investigated the find immediately, and excavated the site the following year.  The bones were found protruding from the base of a sandstone cliff, directly beneath an ancient Anasazi cliff dwelling.  In honor of this, and the fact that the dinosaur’s body had been covered by a collapsing sand dune shortly after it died, the scientists derived the genus name Seitaad from the Navajo name “Seit’aad”, which was a sand monster in tribal legend, that buried its victims in dunes.

The species name, “ruessi”,  comes from the poet and naturalist Everett Ruess who disappeared in southern Utah in 1934.

The specimen comes from the Navajo Sandstone, which is not known for its dinosaur fossils.  While dinosaur specimens have been found in other Utah formations, they are rare in Navajo Sandstone, which is usually known for preserving other, smaller animals.

For more information, please see the PLoS One article at the following link:  http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0009789.





Fossil Bird Oldest So Far Found in North America

23 03 2010

A north Texas fossil enthusiast has found the remains of a new species of bird that is the oldest definitive bird fossil known from North America.  At approximately 96 million years old, the find occupies a gap between the older species found in Europe and Asia, and younger species found in the Americas.

Collector, Kris Howe, was searching an area of exposed rock near Grapevine Lake, northwest of Dallas/Fort Worth International Airport, when he located the find.  Realizing that it was “something special”, he took it to the Museum of Nature & Science in nearby Dallas, where scientists realized it was a new species.

Dr. Tony Fiorillo and Dr. Ron Tykoski, two paleontologists from the Museum, worked on the specimen, publishing their findings in the current issue of the Journal of Vertebrate Paleontology.  “This is the culmination of a dream for any fossil enthusiast,” said Dr. Fiorillo, head paleontologist and Curator at the Museum, in a press release.

The bird, an enantiornithine species named Flexomornis howei, in honor of Howe, dates from the lower Middle Cenomania stage of the Cretaceous period, that occupied shore-lines along the western side of a large inland sea that occupied what is now the U.S. central plains states.