Tag: Archaeology and Anthropology

Tyrannosaurus rex

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Researchers learn more about teen-age T.Rex

Photo by Mike on Pexels.com
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Without a doubt, Tyrannosaurus rex is the most famous dinosaur in the world. The 40-foot-long predator with bone crushing teeth inside a five-foot long head are the stuff of legend. Now, a look within the bones of two mid-sized, immature T. rex allow scientists to learn about the tyrant king’s terrible teens as well.

In the early 2000s, the fossil skeletons of two comparatively small T. rex were collected from Carter County, Montana, by Burpee Museum of Natural History in Rockford, Illinois. Nicknamed “Jane” and “Petey,” the tyrannosaurs would have been slightly taller than a draft horse and twice as long.

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The team led by Holly Woodward, Ph.D., from Oklahoma State University Center for Health Sciences studied Jane and Petey to better understand T. rex life history.

The study “Growing up Tyrannosaurus rex: histology refutes pygmy ‘Nanotyrannus’ and supports ontogenetic niche partitioning in juvenile Tyrannosaurus” appears in the peer-reviewed journal Science Advances.

Co-authors include Jack Horner, presidential fellow at Chapman University; Nathan Myhrvold, founder and CEO of Intellectual Ventures; Katie Tremaine, graduate student at Montana State University; Scott Williams, paleontology lab and field specialist at Museum of the Rockies; and Lindsay Zanno, division head of paleontology at the North Carolina Museum of Natural Sciences. Supplemental histological work was conducted at the Diane Gabriel Histology Labs at Museum of the Rockies/Montana State University.

“Historically, many museums would collect the biggest, most impressive fossils of a dinosaur species for display and ignore the others,” said Woodward. “The problem is that those smaller fossils may be from younger animals. So, for a long while we’ve had large gaps in our understanding of how dinosaurs grew up, and T. rex is no exception.”

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The smaller size of Jane and Petey is what make them so incredibly important. Not only can scientists now study how the bones and proportions changed as T. rex matured, but they can also utilize paleohistology– the study of fossil bone microstructure– to learn about juvenile growth rates and ages. Woodward and her team removed thin slices from the leg bones of Jane and Petey and examined them at high magnification.

“To me, it’s always amazing to find that if you have something like a huge fossilized dinosaur bone, it’s fossilized on the microscopic level as well,” Woodward said. “And by comparing these fossilized microstructures to similar features found in modern bone, we know they provide clues to metabolism, growth rate, and age.”

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The team determined that the small T. rex were growing as fast as modern-day warm-blooded animals such as mammals and birds. Woodward and her colleagues also found that by counting the annual rings within the bone, much like counting tree rings, Jane and Petey were teenaged T.rex when they died; 13 and 15 years old, respectively.

There had been speculation that the two small skeletons weren’t T. rex at all, but a smaller pygmy relative Nanotyrannus. Study of the bones using histology led the researchers to the conclusion that the skeletons were juvenile T. rex and not a new pygmy species.

Instead, Woodward points out, because it took T. rex up to twenty years to reach adult size, the tyrant king probably underwent drastic changes as it matured. Juveniles such as Jane and Petey were fast, fleet footed, and had knife-like teeth for cutting, whereas adults were lumbering bone crushers. Not only that, but Woodward’s team discovered that growing T. rex could do a neat trick: if its food source was scarce during a particular year, it just didn’t grow as much. And if food was plentiful, it grew a lot.

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“The spacing between annual growth rings record how much an individual grows from one year to the next. The spacing between the rings within Jane, Petey, and even older individuals is inconsistent – some years the spacing is close together, and other years it’s spread apart,” said Woodward.

The research by Woodward and her team writes a new chapter in the early years of the world’s most famous dinosaur, providing evidence that it assumed the crown of tyrant king long before it reached adult size.

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About Oklahoma State University Center for Health Sciences

Oklahoma State University Center for Health Sciences educates osteopathic physicians, scientists, allied health professionals and health care administrators for Oklahoma with an emphasis on serving rural and underserved Oklahoma. OSU-CHS offers graduate and professional degrees with over 1,000 students enrolled in academic programs in the College of Osteopathic Medicine, the School of Allied Health, the School of Health Care Administration, the School of Biomedical Sciences, and the School of Forensic Sciences. OSU Medicine operates a network of clinics in the Tulsa area offering a multitude of specialty services including addiction medicine, cardiology, family medicine, internal medicine, pediatrics, psychiatry and women’s health. Learn more at https://health.okstate.edu.

Inbreeding, Small Populations, and Demographic Fluctuations Alone Could Have Led to Neanderthal Extinction

Credit: Petr Kratochvil (CC0)
Neanderthal man

Neanderthal extinction could have occurred without environmental pressure or competition with modern humans

Small populations, inbreeding, and random demographic fluctuations could have been enough to cause Neanderthal extinction, according to a study published November 27, 2019 in the open-access journal PLOS ONE by Krist Vaesen from Eindhoven University of Technology, the Netherlands, and colleagues.

Paleoanthropologists agree that Neanderthals disappeared around 40,000 years ago—about the same time that anatomically modern humans began migrating into the Near East and Europe. However, the role modern humans played in Neanderthal extinction is disputed. In this study, the authors used population modelling to explore whether Neanderthal populations could have vanished without external factors such as competition from modern humans.

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Using data from extant hunter-gatherer populations as parameters, the authors developed population models for simulated Neanderthal populations of various initial sizes (50, 100, 500, 1,000, or 5,000 individuals). They then simulated for their model populations the effects of inbreeding, Allee effects (where reduced population size negatively impacts individuals’ fitness), and annual random demographic fluctuations in births, deaths, and the sex ratio, to see if these factors could bring about an extinction event over a 10,000-year period.

The population models show that inbreeding alone was unlikely to have led to extinction (this only occurred in the smallest model population). However, reproduction-related Allee effects where 25 percent or fewer Neanderthal females gave birth within a given year (as is common in extant hunter-gatherers) could have caused extinction in populations of up to 1,000 individuals. In conjunction with demographic fluctuations, Allee effects plus inbreeding could have caused extinction across all population sizes modelled within the 10,000 years allotted.

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The population models are limited by their parameters, which are based on modern human hunter-gatherers and exclude the impact of the Allee effect on survival rates. It’s also possible that modern humans could have impacted Neanderthal populations in ways which reinforced inbreeding and Allee effects, but are not reflected in the models. 

However, by showing demographic issues alone could have led to Neanderthal extinction, the authors note these models may serve as a “null hypothesis” for future competing theories—including the impact of modern humans on Neanderthals. 

The authors add: “Did Neanderthals disappear because of us? No, this study suggests. The species’ demise might have been due merely to a stroke of bad, demographic luck.” 

‘Ghost’ footprints from Pleistocene era

Photo by Jon Del Rivero

ITHACA, N.Y. –

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Invisible footprints hiding since the end of the last ice age – and what lies beneath them – have been discovered by Cornell University researchers using a special type of radar in a novel way.

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The fossilized footprints reveal a wealth of information about how humans and animals moved and interacted with each other 12,000 years ago.

“We never thought to look under footprints,” said Thomas Urban, research scientist at Cornell and lead author on the study. “But it turns out that the sediment itself has a memory that records the effects of the animal’s weight and momentum in a beautiful way. It gives us a way to understand the biomechanics of extinct fauna that we never had before.”

The researchers examined the footprints of humans, mammoths and giant sloths in the White Sands National Monument in New Mexico. Using ground-penetrating radar (GPR), they were able to resolve 96% of the human tracks in the area under investigation, as well as all of the larger vertebrate tracks.

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“But there are bigger implications than just this case study,” Urban said. “The technique could possibly be applied to many other fossilized footprint sites around the world, potentially including those of dinosaurs. We have already successfully tested the method more broadly at multiple locations within White Sands.”

While these “ghost” footprints can become invisible for a short time after rain and when conditions are just right, “now, using geophysics methods, they can be recorded, traced and investigated in 3D to reveal Pleistocene animal and human interactions, history and mechanics in genuinely exciting new ways,” said co-author Sturt Manning, archaeology professor.

GPR is a nondestructive method that allows researchers to access hidden information without the need for excavation. The sensor – a kind of antenna – is dragged over the surface, sending a radio wave into the ground. The signal that bounces back gives a picture of what’s under the surface.

In addition to this biomechanical treasure trove of data, the GPR technique gives researchers a way to learn about what early humans did when they were not at a campsite or kill site, the two types of archaeological sites best known for this time period.

The study, “3-D Radar Imaging Unlocks the Untapped Behavioral and Biomechanical Archive of Pleistocene Ghost Track,” published in Scientific Reports.

For more information, see this Cornell Chronicle story.

Cornell University has dedicated television and audio studios available for media interviews supporting full HD, ISDN and web-based platforms.

Ancient Egyptians

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In ancient Egypt, Sacred Ibises were collected from their natural habitats to be ritually sacrificed, according to a study released November 13, 2019 in the open-access journal PLOS ONE by Sally Wasef of Griffith University, Australia and colleagues.

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Egyptian catacombs are famously filled with the mummified bodies of Sacred Ibises. Between around 664BC and 250AD, it was common practice for the birds to be sacrificed, or much more rarely worshipped in ritual service to the god Thoth, and subsequently mummified. In ancient sites across Egypt, these mummified birds are stacked floor to ceiling along kilometers of catacombs, totaling many millions of birds. But how the Egyptians got access to so many birds has been a mystery; some ancient texts indicate that long-term farming and domestication may have been employed.

In this study, Wasef and colleagues collected DNA from 40 mummified Sacred Ibis specimens from six Egyptian catacombs dating to around 2500 years ago and 26 modern specimens from across Africa. 14 of the mummies and all of the modern specimens yielded complete mitochondrial genome sequences. These data allowed the researchers to compare genetic diversity between wild populations and the sacrificed collections.

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If the birds were being domesticated and farmed, the expected result would be low genetic diversity due to interbreeding of restricted populations, but in contrast, this study found that the genetic diversity of mummified Ibises within and between catacombs was similar to that of modern wild populations. This suggests that the birds were not the result of centralized farming, but instead short-term taming. The authors suggest the birds were likely tended in their natural habitats or perhaps farmed only in the times of year they were needed for sacrifice.

The authors add: “We report the first complete ancient genomes of the Egyptian Sacred Ibis mummies, showing that priests sustained short-term taming of the wild Sacred Ibis in local lakes or wetlands contrary to centralised industrial scale farming of sacrificial birds.”

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Citation: Wasef S, Subramanian S, O’Rorke R, Huynen L, El-Marghani S, Curtis C, et al. (2019) Mitogenomic diversity in Sacred Ibis Mummies sheds light on early Egyptian practices. PLoS ONE 14(11): e0223964. https://doi.org/10.1371/journal.pone.0223964

Funding: Human Frontier Science is acknowledged for financial support in the form of a grant to DL, SI, BH, and EW(RGP0036/2011). SW thanks Griffith University for a PhD scholarship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing Interests: The authors have declared that no competing interests exist.