Tag: Permian Extinction

Paleontology News for November 2020, two new studies look at the causes and effects of the Permian extinction, the greatest mass dying in the history of Earth.

The asteroid that killed off the dinosaurs 66 million years ago may get more press coverage but when it comes to the biggest extinction event of all time the Permian extinction of 252 million yeas ago has no rival. More than 70% of all land species and 95% of all marine species disappeared within the space of just a few thousand years. And even those species that lived through the extinction must have suffered an unimaginable loss of individuals, leaving the entire Earth an almost lifeless, barren planet.

Along with thousands of other types of living creatures the Permian extinction killing off the last of the Trilobites! (Credit: Science Alert)

Unlike the Cretaceous extinction, which most paleontologists now agree was caused by an asteroid or comet striking our planet; the exact cause of the Permian extinction has been more controversial. The majority opinion is that it was triggered by a massive volcanic outbreak in the region of Russia known as the Siberian Traps. It is thought that the massive amounts of carbon dioxide, sulfur dioxide and other pollutants released by the volcanoes caused tremendous changes in the climate leading to the massive dying. Sound familiar!

Massive volcanic eruptions certainly contributed to the destruction at the end of the Permian but were they the only cause? (Credit: Sci-News.com)
Geological maps of the Siberian Traps region. The huge extent of volcanic rock must have been caused by massive eruptions unlike anything seen on Earth since. (Credit: Saturian Cosmology)

Now a new study by scientists with the European Union funded BASE-LiNE Earth project have been able to outline a blow-by-blow description of the sequence of events that took place 252 million years ago. According to their website the BASE-LiNE Earth project is “… an international training, research and career development network for highly motivated young scientists…” The goal of BASE-LiNE Earth is to “…extend the knowledge on the complex and long-term Phanerozoic seawater history…” In other words the BASE-LiNE Earth scientists hope to use the latest scientific tools to learn more about the conditions in Earth’s oceans throughout the past half billion or more years.

Some of the members of the Base-LiNE Earth Project. (Credit: Base-LiNE Earth)

One of the sources of information that the BASE-LiNE Earth researchers hope to use is the fossilized shells of the marine invertebrates known as brachiopods. These small bivalved creatures are among the earliest animals to develop hard parts and since their shells were produced using the substances in the oceans at the time they lived those fossilized shells still carry the chemical traces of the composition of those ancient waters. By the way, although brachiopods superficially resemble clams in possessing two shells the animal inside those shells was very different, coming from an entirely different phylum.

It’s easy to recognize a brachiopod from a clam because each brachiopod shell is symmetric while it’s only when you put the two clam shells together that you get symmetry. (Credit: Skeptical Squirrel)

Back in the period of Earth’s history before the Permian extinction brachiopods greatly outnumbered clams, dominating the ecosystem of every ocean in the world making them the most common type of fossil from that early period of life. Therefore using brachiopod shells as time capsules of conditions from right before and during the Permian extinction makes perfect sense.

A few species of Brachiopod did survive the Permian extinction but today they are very rare. I have thousands of fossil brachiopod but I’ve never seen a live one! (Credit: www.baseline-earth.eu)

Using well-preserved shells of brachiopods collected from the mountains in the Southern Alps BASE-LiNE team leader Dr. Hana Jurikova was able to determine the pH of the oceans during the course of the Permian extinction. pH of course is a measure of acidity which is directly tied to the amount of carbon-dioxide dissolve in water. Now ocean acidification by itself is deadly to many marine organisms like brachiopods because it reacts with the calcium in their shells weakening and dissolving them. Harming if not actually killing the animal inside. And as we are all aware today the amount of carbon dioxide is also directly linked to the global temperature. So the fossilized shell of an ancient brachiopod can tell us a lot about the world’s temperature 252 million years ago.

Some brachiopod fossils. Since the animal that made them used chemicals absorbed from the seawater in which they lived these shells contain information about the oceans millions of years ago. (Credit : Illinois State Geological Survey)

So the question becomes, did the massive volcanic eruptions of the Siberian Traps release enough carbon dioxide to cause the Permian extinction by itself or were there other factors involved as well? On the basis of their analysis of fossilized brachiopods the BASE-LiNE Earth study team concluded that amount of carbon dioxide in Earth’s oceans and atmosphere was more than sufficient to caused the great dying. If this result holds up it will mean that the smoking gun for the greatest killing in the history of Earth has at last been found.

And if the greatest mass extinction of life on Earth was due to nothing more than carbon dioxide being released into the atmosphere what lesson does that hold of us today. It is true that the fossil fuels we burn for energy aren’t releasing as much carbon dioxide as the Siberian Traps did but hey, we’ve only been at it a 150 years or so. The Permian extinction was just a random act of nature but the extinction event we are causing now will be the work of our own selfishness and stupidity.

If a massive release of CO2 caused the greatest extinction event in Earth’s history you have to ask yourself, are we causing another? (Credit: Scientific American)

But some life did survive the Permian extinction and as the environmental conditions slowly returned to normal those survivors found themselves in an almost empty world, but a world of opportunity. In many ways the whole world was like the newly formed Galapagos islands where only a few creatures were able to colonize and diversify and evolve into many new kinds of animals, like dinosaurs, birds and mammals.

Some of the earliest mammals, known as synapsids, looked more like reptiles but there is evidence that immediately after the Permian extinction some were already developing hair and other more mammalian features. (Credit: Morgan’s Lists)

In fact a new study by Professor Mike Benton and Masters Student Tai Kubo at the University of Bristol in the UK now asserts that it in the period immediately after the Permian extinction that warm-blooded animals first evolved and spread. Professor Benton and Mr. Kubo base their conclusion on an analysis of hundreds of fossilized trackways of four legged vertebrates, reptiles both immediately before and after the Permian event.

What the footprints revealed is a major change in the gait of creatures as they walked. Before the Permian the trackways they found had the left and right feet spread far apart, a gait typical of an animal with a sprawled posture where the legs come out from the side of the body. Such an anatomy is typical of a slow moving cold-blooded animal such as an alligator or lizard. See image below.

The trackways of animals after the Permian extinction indicate a major evolutionary change in the anatomy. (Credit: University of Bristol)

Immediately after the Permian extinction however a new kind of trackway appeared, one where the right and left footprints were much closer together, almost in a line. Such a gait indicates that the animal’s legs come straight down from the body, an anatomy more similar to that of a modern dog or horse, the anatomy of fast moving, warm-blooded animals.

Benton and Kubo recognized that this change occurred in two major groups of reptiles, the synapsids and archosaurs, the ancestors of mammals and dinosaurs/birds respectively. While there had been some evidence of the presence of hair in the synapsids from this time period the work of Benton and Kubo represents the earliest evidence for warm blood in the archosaurs.

The Archosaurs eventually develop into both the Dinosaurs and Birds. (Credit: Britannica Kids)

Of course Professor Benton and Mr. Kubo are assuming that an upright posture is a definitive sign of an animal’s being warm blooded, which may be going a bit too far. While in modern animals the two characteristics may be intimately linked was that true 250 million years ago?

Still the study carried out by the paleontologists is further evidence that mass extinctions, however terrible to the creatures that experience them, can also open up new opportunities for evolution to make great leaps forward. A reminder that, without those mass dyings, we ourselves would not be here.

Paleontology News for February 2019.

There are several items of interest from the world of paleontology for this month; several newly discovered species of early life to discuss. I think I’ll start with the most ancient and work my way forward in time.

250 million years ago life on Earth suffered its greatest mass extinction event. The Permian extinction as it’s known wiped out more than 90% of the species of plants and animals, far more than were killed by the asteroid that ended the reign of the dinosaurs. Paleontologists are intensively interested not only in what caused the Permian extinction, there are many theories, but also how quickly did the Earth’s ecology recover from such a terrible blow.

Today Antarctica may be mostly an icy desert but 250 million years ago it was a warm, lush forest and a new species of reptile from Antarctica is now providing us with a glimpse into that period of recovery. The creature has been given the name Antarctanax shackletoni, the first name means Antarctic King in Greek while the second honours the Antarctic explorer Ernst Shackleton. A shackletoni was a kind of reptile known as an archosaur, a group who are considered to be the ancestor to both the dinosaurs and the crocodiles. About the size of a modern iguana, A shackletoni probably fed on insects and other small prey.

Artists Impression of Antacrtanax shackletoni (Credit: Sci-News.com)

The remains of A shackletoni were discovered in rocks dating to only 2 million years after the Permian extinction indicating that life recovered more quickly than had been previously thought. One theory that is being discussed amongst paleontologists is the idea that extinction events may actually open up ecological niches, spurring evolution to generate entirely new types of living creatures. As an ancestor to both the dinosaurs and crocodiles A shackletoni is strong evidence for that theory.

Fossil Remains of A shackletoni (Credit: Bobr Times)

 

My second story deals with the discovery of a new species of dinosaur proper, although a very strange looking one. We’re all familiar with the largest of the dinosaurs, the long necked, long tailed sauropods along with the stegosaurs, those dinosaurs who had bony plates along their back for protection. See images below.

The Sauropod Dinosaur Diplodocus (Credit: NicePNG.com)

A Typical Stegosaurus (Credit: Cmstudio)

Well how would you like a sauropod with a set of sharp spikes running down its back? That’s just what a team of paleontologists working in the Patagonia region of Argentina has discovered. It’s being called Bajadasaurus pronuspinax; the name means downhill lizard with bent over forward spines and it lived during the lower early Cretaceous period some 140 million years ago. See image below.

Artists impression of Bajadasaurus pronuspinax (Credit: Jorge A. Gonzalez)

Judging from its skull B pronuspinax resembled the more familiar Diplodocus but based on the size of the discovered skeleton B pronuspinax was only some ten meters in length, less than half the size of its enormous relative. According to Pablo Gallina of the National Scientific and Technical Research Council of Argentina and lead author of the paper the bony spines must have been reinforced in some fashion, “We think that had they just been bone structures or covered only by skin, they could have been easily broken or fractured…they probably were covered by a keratin sheath, in a similar way to the horns of mammals such as antelopes.” Either way I’m sure that B pronuspinax would have been a fascinating creature to see.

The Actual Fossil Spines of B pronuspinax (credit: Science Alert)

For my final story I’d like to discuss a type of animal that still exists and with which we are all quite familiar, the kangaroo and when did it evolve its distinctive hop. Now researchers studying fossils of kangaroo ancestors have concluded that 20 million years ago those ancestors could hop, walk on four legs and even climb trees!

Ancestors of the Kangaroos (Credit: Peter Shouten)

The fossils that led to this conclusion come from the northwest region of the state of Queensland near the town of Riversleigh. Most importantly the finds include very rare specimens of the feet of the kangaroo ancestors, see image below, giving clear evidence of their mode of locomotion.

Foot Bones of the 20 Million Year Old Kangaroo Nambaroo gillespieae (Credit: Benjamin Kear)

The long held view was that the hopping motion of kangaroos occurred in the more recent past as a change in climate led to widespread grasslands typical of modern Australia. However these new fossil finds indicate that kangaroo ancestors were hopping very efficiently while most of Australia was still forested. According to Dr. Benjamin Kear of Uppsala University in Sweden and a member of the study, “It all points to an extremely successful animal, that’s superbly adapted to its environment and a whole range of ecosystems and it’s why kangaroos are so successful today.”

So there we have it, three more examples of the fascinating diversity of life here on Earth!