glyptodonts

ERAS OF THE EARTH

It wasn’t long ago that our Earth was thought to be only a few thousand years old and having been created in a matter of days. However during the scientific revolution that was taking place in the 18th and 19th centuries, minds like Darwin, Hutton and Lyell were challenging these age old theories. It was Charles Lyell that pioneered the theory that the forces of physics have remained the same throughout history, James Hutton also expressed that we can interpret the ancient past by studying modern day natural processes because the past and present are governed by the same laws. His findings reported that layers of sediment accumulated at around 2cm per year, he deduced that since mountains are sedimentary formations and thousands of metres high that the planet is more than a few thousand years old, but hundreds of millions. 

Our Earth is actually 4600 million years old, this staggeringly long time is almost impossible for the human mind to comprehend. As far as we know, life emerged as single celled organisms around 3800 million years ago, for the next 3 billion years it would remain as these minute unicellular organisms. This is the Precambrian, 4600 - 570 million years ago. 

To help us grasp the immense history of the Earth, a geological timescale was developed with each period marking a milestone in evolution and life.

CAMBRIAN 540 - 488 million years ago
Named after Cambria, an ancient name for Wales where rocks of this age are greatly exposed.
The Cambrian period sees explosive development of multicellular life with all the main modern phyla being established. Complex eyes and food chains evolve as well as active predation. Life is confined to the sea.

See Hallucigenia Opabinia Anomalocaris  

ORDOVICIAN 488 - 440 million years ago
Named for an ancient welsh tribe, the ordovices who lived in areas where rocks of this age are well exposed. Th oceans flourish with huge diversity of jawless fish, trilobites and gastropods and arthropods begin to dominate. The period ends with arthropods taking the first steps onto land. The end of the ordovician is marked by the first of the five major mass extinctions to hit the planet.

See Pterygotus Cameroceras 

SILURIAN 444 - 416 million years ago
Named for another welsh tribe, the silures, who inhabited areas where rocks of this age are abundant. Life in the oceans recovered from extinctions, magnificent coral reefs thrive in warm seas. Small plants begin to colonise the land and jawed fishes evolve.

DEVONIAN 416 - 359 million years ago
Named after the English county of Devon which is rich in Devonian age rocks and fossils. The Devonian period is also known as the age of the fishes. Jawed fish and placoderm fish rule the oceans, trilobites still thrive. Plants move from the coastal areas deep into land and the first forests spring up. Shark species increase in numbers and early forms of amphibian begin to spend more time on land.

See Dunkleosteus 

CARBONIFEROUS 359 - 299 million years ago
Known as the age of amphibians and named for the ancient coal deposits which were laid down during this time. The land is overrun with lush forests and swamps, The two main continents of the time, Eurasia and Gondwana are colliding to form the supercontinent Pangea. Winged insects take over the skies, oxygen content is much higher that today allowing insects to reach great sizes and the first true reptiles evolve, these are the first truly terrestrial vertebrates.

PERMIAN 299 - 251 million years ago
Named after Perm in Russia where rocks of the age are well exposed. Pangea is covered in harsh deserts, the number of species goes into decline, eventually 95% of them are wiped out in the worst mass extinction ever seen. Mammal like reptiles evolve. The first dinosaurs evolve towards the end of the Permian, they start as a few isolated groups and begin to increase rapidly in numbers.

See Scutosaurus Helicoprion Dimetrodon Gorgonops 

TRIASSIC 251 - 200 million years ago
Named after the word “Trias” referring to 3 rock divisions in Germany called bunter, muschelkalk and keuper. The climate of Pangea is warm and dry and dinosaurs have gradually assumed dominance in the land, skies and oceans. Mammals only exist as a few small species. Ichthyosaurs and plesiosaurs reign in the sea and reach phenomenal size.

See Proterosuchus Tanystropheus 

JURASSIC 200 - 146 million years ago
Named for the Jura mountains. Dinosaurs still dominate the land and the oceans flourish with marine reptiles and ammonites. The first bird start to appear towards the end of the Jurassic.

See Liopleurodon Megalosaurus 

CRETACEOUS 146 - 65 million years ago
Named for the latin “creta” meaning chalk which is laid down during this period and found widely now. Dinosaurs continue to dominate, the first flowering plants evolve. Sea levels are up to 300m higher than today in some areas, much of the land is covered in shallow seas. Carbon dioxide concentrations rise, slowly choking the atmosphere. The end of the cretaceous is marked by the extinction of the dinosaurs due to possible meteor impact.

See Archelon Deinosuchus Ankylosaurus 

PALEOGENE 65 - 23 million years ago
The world begins to recover, mammals and birds begin to flourish and exploit the vacant niches left behind by the dinosaurs, in doing so they grow to incredible sizes. The climate is gradually cooling and will continue to do so bringing the earth into an ice age. In these cooler conditions the first grasses evolve.

See Gastornis Paraceratherium Entelodon Andrewsarchus Ambulocetus

NEOGENE 23 - 2.5 million years ago
The climate is still cooling, ice sheets begin to spread down from the poles, as a result sea levels slowly drop. The size of forests reduce and grasslands take over resulting in vast open planes. Mammals dominate the earth due to their ability to adapt to changing environments and harsh conditions. Towards the end of the period early hominids begin to appear.

See amphicyon Glyptodonts Megalodon

QUATERNARY 2.5 million years ago to present
With an enduring ice age much of the mammalian megafauna have become extinct. Hominids have continued to evolve, only the homo sapiens survive as they are able to adapt.

See Megatherium 

Study Finds Relationship Between Glyptodonts, Modern Armadillos

New research using a novel technique to recover ancient DNA reveals that the evolutionary history of glyptodonts—huge, armored mammals that went extinct in the Americas at the end of the last ice age—is unexpectedly brief.

The work, published this week in the journal Current Biology by an international team of researchers, confirms that glyptodonts likely originated less than 35 million years ago from ancestors within lineages leading directly to one of the modern armadillo families.

Numerous species of glyptodonts lived in dense forests, open grasslands, and a variety of other ecosystems, occupying a range that stretched from what is now the southern part of the United States to the Patagonia region of South America.

“Although their disappearance has been blamed on human depredation as well as climate change, some species persisted into the early part of the modern epoch, long after the disappearance of mammoths and saber-toothed cats,“ saidRoss D.E. MacPhee, an author on the study and curator in the Museum’s Department of Mammalogy. "Like the loss of giant ground sloths, mastodons, and dozens of other remarkable mammalian species, the precise cause of the New World megafaunal extinctions remains uncertain.”

Although scientists including Charles Darwin collected partial remains of glyptodonts in the early 19th century, at first nobody knew what kind of mammal they represented. It was eventually accepted that glyptodonts must be related in some way to armadillos, the only other New World mammals to develop a protective bony shell. However, because of the many physical differences between these two groups, most paleontologists have held the view that they must have separated very early in their evolutionary history.

To try and clarify this poorly understood history, researchers Frédéric Delsuc of the French National Center for Scientific Research at the University of Montpellier and Hendrik Poinar of McMaster University worked alongside MacPhee to learn what genetic information on these ancient armored animals could reveal.

As is often the case in ancient DNA investigations, fossil genomic material is poorly preserved, and only one sample worked—a carapace fragment of an undetermined species of Doedicurus, a gigantic glyptodont that lived until about 10,000 years ago. Using a novel approach to recover genetic information from ancient specimens, the team successfully assembled the complete mitochondrial genome of Doedicurus and compared it to that of all modern xenarthrans, a group of mammals including armadillos, sloths, and anteaters.

The researchers found that instead of representing a very early, independent branch of armored xenarthrans, glyptodonts likely had a much later origin, from ancestors within lineages leading to the modern armadillo family Chlamyphoridae.

More surprising still, the study finds that the closest relatives of glyptodonts—some species of which may have weighed 2 tons or more—include not only the giant armadillo (Priodontes maximus), which can weigh up to 25 pounds, but also the 4-ounce pink fairy armadillo, or pichiciego (Chlamyphorus truncatus).

“Contrary to what is generally assumed about the distinctiveness of glyptodonts, our analyses indicate that they originated only some 35 million years ago, well within the armadillo radiation,” Delsuc said. “Taxonomically, they should be regarded as no more than another subfamily of armadillos, which we can call Glyptodontinae.”

This post was originally published on the Museum blog. 

This Fossil Friday is all in the family…the armadillo family, that is! 

This is Panochthus frenzelianus, a giant glyptodont that lived in South America, just before the extinction of the glyptodonts, at the end of the last ice age, about 30,000 years ago. Some glyptodonts grew to be over 10 feet long and may have weighed as much as a ton, including the shell. 

Although scientists including Charles Darwin collected partial remains of glyptodonts in the early 19th century, at first nobody knew what kind of mammal they represented. It was eventually accepted that glyptodonts must be related in some way to armadillos, the only other New World mammals to develop a protective bony shell. However, because of the many physical differences between these two groups, most paleontologists have held the view that they must have separated very early in their evolutionary history.

Just this week, new research by an international team of researchers, including Ross MacPhee from AMNH, that used a novel technique to recover ancient DNA revealed that instead of representing a very early, independent branch of armored xenarthrans, glyptodonts likely had a much later origin, from ancestors within lineages leading to the modern armadillo family Chlamyphoridae.

“Contrary to what is generally assumed about the distinctiveness of glyptodonts, our analyses indicate that they originated only some 35 million years ago, well within the armadillo radiation,” said researcher Frédéric Delsuc of the French National Center for Scientific Research. “Taxonomically, they should be regarded as no more than another subfamily of armadillos, which we can call Glyptodontinae.”

Learn more about this new research

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Glyptodonts and Armadillos in AMNH.
The giant one is a Panochthus, a badly photographed skull of Glyptotherium (in second image), the small Propalaehoplophorus and a modern armadillo, the six-banded armadillo (Euphractus sexcinctus).

Gliptodontes y Armadillos en el AMNH.
El gigante es un Panochthus, luego esta un cráneo mal fotografiado de Glyptotherium (en la segunda imagen), el pequeño Propalaehoplophorus y un armadillo moderno, el tatú peludo (Euphractus sexcinctus).

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Glyptodonts

Looking like tanks rolling across the landscape, this family of mammals (related to modern armadillos and sloths) was a common sight across South America during the Pleistocene epoch (2.5 million to 11,700 years ago). The era of the ice ages saw a wide variety of large mammals spread across the continent, including the giant sloths that grace many a natural history museum. They were the size of a small car, growing up to 3.3 metres long and first evolved in the Miocene (23-2.5 million years back).

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