Mammal-like reptiles, warm-blooded earlier than thought


This video says about itself:

19 May 2016

Ophiacodon (meaning “snake tooth”) is an extinct genus of synapsids belonging to the family Ophiacodontidae that lived from the Late Carboniferous to the Early Permian in North America and possibly Europe. The genus was named along with its type species O. mirus by paleontologist Othniel Charles Marsh in 1878 and currently includes five other species. As an ophiacodontid, Ophiacodon is one of the most basal synapsids and is close to the evolutionary line leading to mammals.

Music: Pianoman by Billy Joel.

From the University of Bonn in Germany:

Warm-bloodedness possibly much older than previously thought

Characteristic may have developed 20 million years earlier, study shows

May 18, 2017

Summary: Warm-bloodedness in land animals could have evolved much earlier than previously thought, suggests a study of the bones of the long-extinct mammal predecessor Ophiacodon.

Warm-bloodedness in land animals could have developed in evolution much earlier than previously thought. This is shown by a recent study at the University of Bonn, which has now been published in the journal Comptes Rendus Palevol.

People who like watching lizards often get the best opportunity to do so in the morning, as they can usually be found sunbathing at this time of day. This is because they rely on an external energy supply to reach their operating temperature. However, mice and other mammals make themselves nice and cozy in a different way: they burn calories and can even keep themselves warm during a bitterly cold winter’s night.

Mammals are thus referred to as warm-blooded. Until now, it was thought that the “body heater” was invented in four-legged land animals around 270 million years ago. “However, our results indicate that warm-bloodedness could have been created 20 to 30 million years earlier,” explains Prof. Martin Sander from the Steinmann Institute for Geology, Mineralogy and Paleontology at the University of Bonn.

Bones as a thermometer

For long-extinct animals, it is naturally not possible to simply determine body temperature using a thermometer. However, warm-bloodedness leaves behind tell-tale signs in fossils. It not only means that the animal is not reliant on the ambient temperature, but also enables faster growth. “And this is shown in the structure of the bones,” explains Sander.

Bones are composites of protein fibers, collagen, and a biomaterial, hydroxyapatite. The more orderly the arrangement of the collagen fibers, the more stable the bone, but the more slowly it normally grows as well. The bones of mammals thus have a special structure. This allows them to grow quickly and yet remain stable. “We call this bone form fibrolamellar,” says the paleontologist.

Together with his PhD student Christen D. Shelton (now at the University of Cape Town), the scientist looked at humerus bones and femurs from a long-extinct land animal: the mammal predecessor Ophiacodon. This lived 300 million years ago. “Even in Ophiacodon, the bones grew as fibrolamellar bones,” says Sander to summarize the analysis results. “This indicates that the animal could already have been warm-blooded.”

Ophiacodon was up to two meters long, but otherwise resembled today’s lizards — and not without good reason: mammals and reptiles are related; they thus share a predecessor. In the family tree, Ophiacodon is very close to the place where these two branches separate.

Were the first reptiles warm-blooded?

However, lizards, turtles and other reptiles living today are cold-blooded. Until now, it has been assumed that this was the original form of the metabolism — i.e. that the shared ancestor of both animal groups was cold-blooded. Warm-bloodedness would thus be a further development, which arose over the course of mammalian evolution.

However, Ophiacodon appears a very short time after the division between mammals and reptiles. “This raises the question of whether its warm-bloodedness was actually a completely new development or whether even the very first land animals before the separation of both branches were warm-blooded,” says Sander. That is just speculation. However, if this theory is correct, we would have to drastically correct our image: the first reptiles would then also have been warm-blooded — and would have only discarded this type of metabolism later.

‘Mass extinctions killed less wildlife than thought’


This video from Britain says about itself:

Catastrophe – The Permian Extinction

The Permian-Triassic extinction event, informally known as the Great Dying, was an extinction event that occurred 252 million years ago, forming the boundary between the Permian and Triassic geologic periods, as well as the Paleozoic and Mesozoic eras. It is the Earth’s most severe known extinction event, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct. It is the only known mass extinction of insects. Some 57% of all families and 83% of all genera became extinct. Because so much biodiversity was lost, the recovery of life on Earth took significantly longer than after any other extinction event, possibly up to 10 million years.

Presented by Tony Robinson.

Originally published in 2008 by Channel 4

That was the prevalent view in 2008. And now …

From the Proceedings of the National Academy of Sciences of the United States of America:

Estimates of the magnitudes of major marine mass extinctions in earth history

Steven M. Stanley

October 3, 2016

Significance

This paper shows that background extinction definitely preceded mass extinctions; introduces a mathematical method for estimating the amount of this background extinction and, by subtracting it from total extinction, correcting estimates of losses in mass extinctions; presents a method for estimating the amount of erroneous backward smearing of extinctions from mass extinction intervals; and introduces a method for calculating species losses in a mass extinction that takes into account clustering of losses. It concludes that the great terminal Permian crisis eliminated only about 81% of marine species, not the frequently quoted 90–96%. Life did not almost disappear at the end of the Permian, as has often been asserted.

Abstract

Procedures introduced here make it possible, first, to show that background (piecemeal) extinction is recorded throughout geologic stages and substages (not all extinction has occurred suddenly at the ends of such intervals); second, to separate out background extinction from mass extinction for a major crisis in earth history; and third, to correct for clustering of extinctions when using the rarefaction method to estimate the percentage of species lost in a mass extinction. Also presented here is a method for estimating the magnitude of the Signor–Lipps effect, which is the incorrect assignment of extinctions that occurred during a crisis to an interval preceding the crisis because of the incompleteness of the fossil record.

Estimates for the magnitudes of mass extinctions presented here are in most cases lower than those previously published. They indicate that only ∼81% of marine species died out in the great terminal Permian crisis, whereas levels of 90–96% have frequently been quoted in the literature. Calculations of the latter numbers were incorrectly based on combined data for the Middle and Late Permian mass extinctions. About 90 orders and more than 220 families of marine animals survived the terminal Permian crisis, and they embodied an enormous amount of morphological, physiological, and ecological diversity. Life did not nearly disappear at the end of the Permian, as has often been claimed.

Mid-Permian extinction of animals, new study


This 2013 video says about itself:

Animal Armageddon The Great Dying – Episode 5

The Permian-Triassic extinction event, informally known as the Great Dying, was an extinction event that occurred 252 million years ago, forming the boundary between the Permian and Triassic geologic periods, as well as the Paleozoic and Mesozoic eras. It is the Earth’s most severe known extinction event, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct. It is the only known mass extinction of insects. Some 57% of all families and 83% of all genera became extinct. Because so much biodiversity was lost, the recovery of life on Earth took significantly longer than after any other extinction event, possibly up to 10 million years.

Researchers have variously suggested that there were from one to three distinct pulses, or phases, of extinction. There are several proposed mechanisms for the extinctions; the earlier phase was likely due to gradual environmental change, while the latter phase has been argued to be due to a catastrophic event. Suggested mechanisms for the latter include large or multiple impact events, increased volcanism, coal/gas fires and explosions from the Siberian Traps, and sudden release of methane from the sea floor; gradual changes include sea-level change, increasing aridity, and a shift in ocean circulation driven by climate change.

From the Geological Society of America:

15 April 2015

New evidence adds the Capitanian extinction to the list of major extinction crises

Boulder, Colo., USA – Since the Cambrian Explosion, ecosystems have suffered repeated mass extinctions, with the “Big 5” crises being the most prominent. Twenty years ago, a sixth major extinction was recognized in the Middle Permian (262 million years ago) of China, when paleontologists teased apart losses from the “Great Dying” at the end of the period. Until now, this Capitanian extinction was known only from equatorial settings, and its status as a global crisis was controversial.

David P.G. Bond and colleagues provide the first evidence for severe Middle Permian losses amongst brachiopods in northern paleolatitudes (Spitsbergen). Their study shows that the Boreal crisis coincided with an intensification of marine oxygen depletion, implicating this killer in the extinction scenario.

The widespread loss of carbonates across the Boreal Realm also suggests a role for acidification. The new data cements the Middle Permian crisis’s status as a true “mass extinction.” Thus the “Big 5” extinctions should now be considered the “Big 6.”

An abrupt extinction in the Middle Permian (Capitanian) of the Boreal Realm (Spitsbergen) and its link to anoxia and acidification: David P.G. Bond et al., University of Hull, Hull, UK. Published online ahead of print on 14 Apr. 2015; http://dx.doi.org/10.1130/B31216.1. This article is OPEN ACCESS (available for free online).

Ancient tree rings from the Permian period record a roughly 11-year cycle of wet and dry periods, climate fluctuations caused by the ebbing and flowing of solar activity, researchers propose January 9 in Geology. The discovery would push back the earliest evidence of today’s 11-year solar cycle by tens of millions of years: here.

Dimetrodon ancient reptile, new discoveries


This dimetrodon video is called Paleoworld– Tale Of A Sail (Part 1).

From Sci-News.com:

Dimetrodon Had Steak-Knife Teeth, Scientists Say

Feb 10, 2014

An international team of paleontologists suggests dimetrodon – a 4-m-long prehistoric reptile that lived during the early Permian period, between 295 million and 272 million years ago, and went extinct about 40 million years before the appearance of first dinosaurs – was the first terrestrial vertebrate to develop serrated ziphodont teeth.

Dimetrodon was the top of the terrestrial food chain in the early Permian and is considered to be the forerunner of mammals.

According to a new study reported in the journal Nature Communications, dimetrodons had a diversity of previously unknown tooth structures and were also the first terrestrial vertebrate to develop cusps – teeth with raised points on the crown, which are dominant in mammals.

The study also suggests ziphodont teeth were confined to later species of dimetrodon, indicating a gradual change in feeding habits.

“This research is an important step in reconstructing the structure of ancient complex communities,” said senior author Prof Robert Reisz from the University of Toronto Mississauga.

“Teeth tell us a lot more about the ecology of animals than just looking at the skeleton.”

“We already know from fossil evidence which animals existed at that time but now with this type of research we are starting to piece together how the members of these communities interacted.”

Prof Reisz and his co-author, Kirstin Brink from the University of Toronto Mississauga, studied the changes in dimetrodon teeth across 25 million years of evolution.

The analysis indicated the changes in tooth structure occurred in the absence of any significant evolution in skull morphology. This indicates a change in feeding style and trophic interactions.

Enhanced by Zemanta

Niger Permian reptile fossil discovery


After the South African discovery of an early Triassic amphibian and a mammal-like reptile together … now a discovery from a few million years earlier, more to the north in Africa.

Bunostegos

From the BBC:

24 June 2013 Last updated at 19:02 GMT

A bizarre reptile with knobbly growths on its head roamed a vast, isolated desert about 260 million years ago, researchers say.

New fossils from northern Niger in Africa have been described in the Journal of Vertebrate Paleontology.

The distinctive creature belongs to a new genus of pareiasaur – plant-eating creatures that flourished during the Permian period.

The cow-sized specimen has been named Bunostegos, which means “knobby roof”.

During Permian times, the Earth was dominated by a single supercontinent called Pangaea.

Animal and plant life dispersed broadly across the land, as documented by identical fossil species found on multiple modern continents.

But the new research by an international team supports the idea that there was an isolated desert in the middle of Pangaea with distinctive animals.

Most pareiasaurs had bony knobs on their skulls, but Bunostegos sported the largest, most bulbous ones ever seen in this group, which were common in the Middle and Late Permian, about 266-252 million years ago.

In life, these were probably skin-covered horns like those on the heads of modern giraffes.

“We can’t say for sure, but it is most likely that the bony knobs on the skull of pareiasaurs did not serve a protective function,” Dr Linda Tsuji from the University of Washington in Seattle told BBC News.

“They vary quite markedly in size and shape between different species, with some species lacking prominent knobs entirely, so I think that they were purely ornamental. The most probable use was for inter-specific (between species) or intra-specific (within species) recognition.”

Dr Tsuji and colleagues performed an analysis showing that Bunostegos was actually more closely related to older and more primitive pareiasaurs.

This led them to the conclusion that its genealogical lineage had been isolated for millions of years.

Climatic conditions may have conspired to corral Bunostegos – along with several other reptiles, amphibians, and plants – and keep them constrained to the central, arid area of the supercontinent.

“Our work supports the theory that central Pangea was climatically isolated, allowing a unique relict fauna to persist into the Late Permian,” said Christian Sidor, another author of the paper.

This surprised the scientists because areas outside this central region show fossil evidence of regular faunal interchange.

Geological data show that central Pangaea was extremely dry, discouraging some animals from passing through, while keeping those within from venturing out.

The long period of isolation under these parched conditions gave Bunostegos lineage time to evolve its unique anatomical features.

Much of what was once central Pangaea remains to be explored by palaeontologists.

“It is important to continue research in these under-explored areas,” said Dr Tsuji.

“The study of fossils from places like northern Niger paints a more comprehensive picture of the ecosystem during the Permian era.”

See also here.

To Longyearbyen, Svalbard, Arctic


This video is about a plane landing at LYR airport, Longyearbyen, Svalbard, in May 2007.

2 June 2013.

I have been to the Antarctic.

But I had never been to the high Arctic so far. The closest I came were the Lofoten islands of Norway, and Iceland, both near the Arctic circle.

Now, however, to Svalbard. This Arctic archipelago is about halfway between northern Norway and the North Pole. Outside Norway, the islands are often called Spitsbergen; in Norwegian, the name of the largest island.

First, our plane went to Oslo, the capital of Norway.

After some hours waiting, we transferred to a smaller plane.

At 10pm, it passed the Arctic circle, flying near Bodø in northern Norway.

23:05: we pass Bear Island, about half way between Svalbard and continental Norway. Officially, Bear Island is the southernmost island of the Svalbard archipelago. It is uninhabited now, except for a meteorological station.

South western Spitsbergen from the air, 2 June 2013

Then, the plane reached the mountains of the west coast of Spitsbergen island.

South western Spitsbergen mountains from the air, 2 June 2013

This video is called Landing at Longyearbyen / Svalbard lufthavn (LYR) on 8 April 2009 on a flight from Ny-Ålesund.

Almost at midnight of 2 June, we landed at the airport of Longyearbyen, the capital (basically: the only sizable village) of Svalbard.

We drove from the airport to Longyearbyen village.

It is Arctic summer. So, the sun never sets now.

Svalbard is one of not so many countries where there has never been a visit to Dear Kitty. Some blog yet. Not that surprising: only 2,500 people live there, not all of them fanatical Internauts.

During the next days, there were will be photos of birds, other wildlife of Svalbard and other sides of Svalbard on this blog.

About Svalbard prehistory:

Bryozoans from the Lower Permian Treskelodden and Wordiekammen formations of southern and central Spitsbergen respectively, Svalbard, have been studied. Twenty species are identified, including one new genus, Toulapora gen. nov., with Toulapora svalbardense as type species and one new species, Ascopora birkenmajeri sp. nov. The taxonomic composition is typical Lower Permian, with species in common with Timan−Pechora and the Urals (Russia) and Ellesmere Island (the Canadian Arctic). Growth habits reflect a moderately to deeper shelf environment.