Tag: All Journal News

Dinosaur Embryos

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Eggs Took 3 to 6 Months to Hatch

Research on the teeth of fossilized dinosaur embryos indicates that the eggs of non-avian dinosaurs took a long time to hatch–between about three and six months. The study, led by scientists at Florida State University, the American Museum of Natural History, and the University of Calgary, was published today in the Proceedings of the National Academy of Sciences and finds that contrary to previous assumptions, dinosaur incubation is more similar to that of typical reptiles than of birds. The work suggests that prolonged incubation may have affected dinosaurs’ ability to compete with more rapidly generating populations of birds, reptiles, and mammals following the mass extinction event that occurred 65 million years ago.

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Credit: © AMNH/M. Ellison
This is a photo of a hatchling Protoceratops andrewsi fossil from the Gobi Desert Ukhaa Tolgod, Mongolia.
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“We know very little about dinosaur embryology, yet it relates to so many aspects of development, life history, and evolution,” said study co-author Mark Norell, Macaulay Curator of Paleontology at the American Museum of Natural History. “But with the help of advanced tools like CT scanners and high-resolution microscopy, we’re making discoveries that we couldn’t have imagined 20 years ago. This work is a great example of how new technology and new ideas can be brought to old problems.”

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Because birds are living dinosaurs, scientists have long assumed that the duration of dinosaur incubation was similar to birds, whose eggs hatch within 11 to 85 days. The research team tested this theory by looking at the fossilized teeth of two extremely well-preserved ornithischian dinosaur embryos on each end of the size spectrum: Protoceratops–a pig-sized dinosaur found by Norell and colleagues in the Mongolian Gobi Desert, whose eggs were quite small at 194 grams, or a little less than half of a pound–and Hypacrosaurus, a very large duck-billed dinosaur found in Alberta, Canada, with eggs weighing more than 4 kilograms, or nearly 9 pounds. First, the researchers scanned the embryonic jaws of the two dinosaurs with computed tomography (CT) at the Museum’s Microscopy and Imaging Facility to visualize the forming dentitions. Then they used an advanced microscope to look for and analyze the pattern of “von Ebner” lines–growth lines that are present in the teeth of all animals, humans included. This study marks the first time that these growth lines have been identified in dinosaur embryos.

“These are the lines that are laid down when any animal’s teeth develops,” said lead author and Florida State University professor Gregory Erickson. “They’re kind of like tree rings, but they’re put down daily. And so we could literally count them to see how long each dinosaur had been developing.”

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Using this method, the scientists determined that the Protoceratops embryos were about three months old when they died and the Hypacrosaurus embryos were about six months old. This places non-avian dinosaur incubation more in line with that of their reptilian cousins, whose eggs typically take twice as long as bird eggs to hatch–weeks to many months. The work implies that birds likely evolved more rapid incubation rates after they branched off from the rest of the dinosaurs. The authors note that the results might be quite different if they were able to analyze a more “bird-like” dinosaur, like Velociraptor. But unfortunately, very few fossilized dinosaur embryos have been discovered.

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“A lot is known about growth in dinosaurs in their juvenile to adult years,” said co-author Darla Zelenitsky, from the University of Calgary. “Time within the egg is a crucial part of development with major biological ramifications, but is poorly understood because dinosaur embryos are rare.”

The study also has implications for dinosaur extinction. Prolonged incubation exposed non-avian dinosaur eggs and attending parents to predators, starvation, and environmental disruptions such as flooding. In addition, slower embryonic development might have put them at a disadvantage compared to other animals that survived the Cretaceous-Paleogene extinction event.

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Florida State University graduate student David Kay also is an author on this paper.

This work was funded, in part, by the U.S. National Science Foundation, grant # EAR 0959029, the Macaulay Family, and the Natural Sciences and Engineering Research Council of Canada, grant # 327513-09.

AMERICAN MUSEUM OF NATURAL HISTORY (AMNH.ORG)

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The American Museum of Natural History, founded in 1869, is one of the world’s preeminent scientific, educational, and cultural institutions. The Museum encompasses 45 permanent exhibition halls, including the Rose Center for Earth and Space and the Hayden Planetarium, as well as galleries for temporary exhibitions. It is home to the Theodore Roosevelt Memorial, New York State’s official memorial to its 33rd governor and the nation’s 26th president, and a tribute to Roosevelt’s enduring legacy of conservation. The Museum’s five active research divisions and three cross-disciplinary centers support approximately 200 scientists, whose work draws on a world-class permanent collection of more than 33 million specimens and artifacts, as well as specialized collections for frozen tissue and genomic and astrophysical data, and one of the largest natural history libraries in the world. Through its Richard Gilder Graduate School, it is the only American museum authorized to grant the Ph.D. degree and the Master of Arts in Teaching degree. Annual attendance has grown to approximately 5 million, and the Museum’s exhibitions and Space Shows can be seen in venues on five continents. The Museum’s website and collection of apps for mobile devices extend its collections, exhibitions, and educational programs to millions more beyond its walls. Visit amnh.org for more information.

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.

Marijuana Use in E-Cigarettes Increases Among Youth

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Photo by Kimzy Nanney

A study published today online in the Journal of the American Medical Association (JAMA) found marijuana use in electronic cigarettes has been increasing among U.S. middle and high school students from 2017 to 2018.

In the observational study, Hongying “Daisy” Dai, Ph.D., associate professor, University of Nebraska Medical Center College of Public Health used the National Youth Tobacco Survey to analyze responses from 38,000 students, grades 6-12. Dr. Dai, who has been studying e-cigarette use for five years, said e-cigarettes recently have increased very quickly among adolescents.

Among all students, the proportion who reported ever using marijuana in an e-cigarette increased from 11.1% in 2017 to 14.7% in 2018. The increases were seen among some demographic groups, including adolescents age 13 to 17 and Caucasian and Hispanic students.

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“These statistics are very concerning as marijuana use in adolescence could lead to adverse effects in brain development, mental health and academic performance,” said Dr. Dai, a biostatistician. “Our other concern is e-cigarette use has also been related to severe respiratory diseases.

As of Nov. 20, Dr. Dai noted there had been 2,290 vaping-related lung injury cases and 47 deaths. About 77% of the cases were in people with a history of vaping products containing THC, the mind-altering ingredient found in the cannabis plant.

In 2018, the number of students using marijuana in e-cigarettes included:

  • 42.7% of students who ever used e-cigarettes;
  • 53.5% of current e-cigarette users; and
  • 71.6% of multiple tobacco product users. 

Dr. Dai said the increase in marijuana use in e-cigarettes could be attributable to:

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  • the increase of “pod mod” e-cigarette products – small, easy-to-conceal devices that aerosolize liquid solutions containing nicotine, flavoring and other contents;
  • access to marijuana through informal sources such as friends, family members and illicit dealers; and
  • reduced perception among adolescents of the harms of marijuana use.

“Parents really need to raise their awareness about vaping. E-cigarette products look much like school supplies, so it’s hard for parents to know if their child is using e-cigarettes,” she said. “Even for me, it’s hard to distinguish between school supplies and e-cigarette products.”

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She said a limitation of the study is that the information was self-reported. She added that studies about the short- and long-term health effects of using marijuana in e-cigarettes need to be done.

The study was supported by the National Cancer Institute and U.S. Food and Drug Administration Center for Tobacco Products.

We are Nebraska Medicine and UNMC. Our mission is to lead the world in transforming lives to create a healthy future for all individuals and communities through premier educational programs, innovative research and extraordinary patient care.

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.” 

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.

Deep sea vents had ideal conditions for origin of life

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Photo by Silas Baisch
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By creating protocells in hot, alkaline seawater, a UCL-led research team has added to evidence that the origin of life could have been in deep-sea hydrothermal vents rather than shallow pools.

Previous experiments had failed to foster the formation of protocells – seen as a key stepping stone to the development of cell-based life – in such environments, but the new study, published in Nature Ecology & Evolution, finds that heat and alkalinity might not just be acceptable, but necessary to get life started.

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“There are multiple competing theories as to where and how life started. Underwater hydrothermal vents are among most promising locations for life’s beginnings – our findings now add weight to that theory with solid experimental evidence,” said the study’s lead author, Professor Nick Lane (UCL Genetics, Evolution & Environment).

Deep under the Earth’s seas, there are vents where seawater comes into contact with minerals from the planet’s crust, reacting to create a warm, alkaline (high on the pH scale) environment containing hydrogen. The process creates mineral-rich chimneys with alkaline and acidic fluids, providing a source of energy that facilitates chemical reactions between hydrogen and carbon dioxide to form increasingly complex organic compounds.

Some of the world’s oldest fossils, discovered by a UCL-led team, originated in such underwater vents.

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Scientists researching the origins of life have made great progress with experiments to recreate the early chemical processes in which basic cell formations would have developed. The creation of protocells has been an important step, as they can be seen as the most basic form of a cell, consisting of just a bilayer membrane around an aqueous solution – a cell with a defined boundary and inner compartment.

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Previous experiments to create protocells from naturally-occurring simple molecules – specifically, fatty acids – have succeeded in cool, fresh water, but only under very tightly controlled conditions, whereas the protocells have fallen apart in experiments in hydrothermal vent environments.

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The study’s first author, Dr Sean Jordan (UCL Genetics, Evolution & Environment), said he and his colleagues identified a flaw in the previous work: “Other experiments had all used a small number of molecule types, mostly with fatty acids of the same size, whereas in natural environments, you would expect to see a wider array of molecules.”

For the current study, the research team tried creating protocells with a mixture of different fatty acids and fatty alcohols that had not previously been used.

The researchers found that molecules with longer carbon chains needed heat in order to form themselves into a vesicle (protocell). An alkaline solution helped the fledgling vesicles keep their electric charge. A saltwater environment also proved helpful, as the fat molecules banded together more tightly in a salty fluid, forming more stable vesicles.

For the first time, the researchers succeeded at creating self-assembling protocells in an environment similar to that of hydrothermal vents. They found that the heat, alkalinity and salt did not impede the protocell formation, but actively favoured it.

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“In our experiments, we have created one of the essential components of life under conditions that are more reflective of ancient environments than many other laboratory studies,” Dr Jordan said.

“We still don’t know where life first formed, but our study shows that you cannot rule out the possibility of deep-sea hydrothermal vents.”

The researchers also point out that deep-sea hydrothermal vents are not unique to Earth.

Professor Lane said: “Space missions have found evidence that icy moons of Jupiter and Saturn might also have similarly alkaline hydrothermal vents in their seas. While we have never seen any evidence of life on those moons, if we want to find life on other planets or moons, studies like ours can help us decide where to look.”

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The study involved researchers from UCL and Birkbeck, University of London, and was funded by the BBSRC and bgC3.