Category: animals

Endangered species on supermarket shelves

Lab reveals the surprising prevalence of European Eel in Hong Kong’s food supply

Imagine purchasing products from your local grocer, only to find out that those products are comprised of critically endangered species! That’s what a team from the University of Hong Kong, Division of Ecology and Biodiversity has recently discovered on Hong Kong supermarket shelves. A team led by Dr David Baker from the University’s Conservation Forensics laboratory, has recently published the results from an investigation into European eel products on sale in Hong Kong supermarkets.

The study, published in Science Advances, found that nearly 50% of retail eel products, ranging from fillets to snack items from grocers and convenience stores, contained a critically endangered species of fish. According to the IUCN, The European eel (Anguilla anguilla) is at risk of extinction. For this reason, trade in European eels and their food product derivatives is subject to international regulation under the Convention for the International Trade of Endangered Species (CITES). CITES is meant to ensure that permits are required for their import and export in an effort to regulate trade and foster conservation.

Eel, extremely popular in East Asia and particularly Japan, has traditionally been fished from East Asian populations of the Japanese eel (Anguilla japonica). However, overexploitation due to growing demand from Mainland China and a combination of threats ranging from rising ocean temperatures, parasites, and dammed rivers have led to dramatic declines in eel populations. This is true not only for European and Japanese species, but also for their American and Indo-Pacific relatives.

To satisfy demand for eel in East Asia, juvenile eels (known as glass eels) are caught while swimming upstream in their native range spanning Europe and North Africa, and smuggled to Asia to be raised to maturity. To date, captive breeding of eels has not been economically viable; wild-caught glass eels are thus used to “seed” eel farms. In recent years the illegal trade has been highlighted by a number of high-profile investigations and increasing prosecutions.

“The illegal export of glass eels from Europe to Asia has now been recognised as one of the world’s greatest wildlife crimes and Europol has estimated the scale of over 300 million eels (2018 data) annually. The next step is to investigate the global consumer markets to identify where these trafficked eels are eventually consumed. The numbers from Hong Kong are very alarming and reflect the huge amounts of European eels that are being farmed in Asia. It is now up to individual countries to investigate the scale of European eels entering their national food chains illegally.” -Florian Stein, Sustainable Eel Group

The international trade in glass eels is incredibly lucrative. One kilogram of glass eels can contain up to 3,500 individuals and has been recorded selling for over HKD$50,000 on the black market. This highly profitable trade has attracted the attention of international criminal syndicates, who smuggle glass eels in suitcases from Europe to Asia for resale. In their juvenile stages, eels are extremely difficult to identify to the species level. The two most common cousins of the endangered European eel (the Japanese and American eel) are not listed in CITES, therefore no permit is required for their trade. Because of the challenges in visual identification, endangered European eels can be laundered along with their legally traded relatives.

Already, the existence of Europe-Asia smuggling routes has been documented, but the ultimate destination of the smuggled eels remained elusive. Originally conceived as an undergraduate project looking at seafood mislabeling, the investigation into European eel took off when students noticed a surprising amount of European eel present in supermarket products.

“The eel project is the most exciting thing I have done during my undergraduate study in HKU. I once thought research was only for postgraduates and professors, but it turns out I, even as a student, was able to do meaningful research that actually made an impact in illegal trading. This has made me more determined to continue work in environmental fields.” -Haze Chung, Year 4 Undergraduate Researcher

The study covered a wide range of Hong Kong supermarkets and convenience stores across all districts. Surprisingly, almost 50% of the eel products surveyed were determined to be European eel. The results from this study suggested that large scale smuggling networks trafficking European eels are interwoven with local supplier chains, resulting in endangered species ending up on supermarket shelves, totally unbeknownst to consumers.

The “Firewalkers” of Karoo: Dinosaurs and Other Animals Left Tracks in a “Land of Fire”

Several groups of reptiles persisted in Jurassic Africa even as volcanism ruined their habitat

Credit: Bordy et al, 2020
Palaeoenvironmental reconstruction of the Highlands ichnosite at the Pliensbachian–Toarcian boundary.

In southern Africa, dinosaurs and synapsids, a group of animals that includes mammals and their closest fossil relatives, survived in a “land of fire” at the start of an Early Jurassic mass extinction, according to a study published January 29, 2020 in the open-access journal PLOS ONE by Emese M. Bordy of the University of Cape Town and colleagues.

Southern Africa

The Karoo Basin of southern Africa is well-known for its massive deposits of igneous rocks left behind by extensive basaltic lava flows during the Early Jurassic. At this time, intense volcanic activity is thought to have had dramatic impacts on the local environment and global atmosphere, coincident with a worldwide mass extinction recorded in the fossil record. The fossils of the Karoo Basin thus have a lot to tell about how ecosystems responded to these environmental stresses.

Study

In this study, Bordy and colleagues describe and identify footprints preserved in a sandstone layer deposited between lava flows, dated to 183 million years ago. In total, they report five trackways containing a total of 25 footprints, representing three types of animals: 1)  potentially small synapsids, a group of animals that includes mammals and their forerunners; 2) large, bipedal, likely carnivorous dinosaurs; and 3) small, quadrupedal, likely herbivorous dinosaurs represented by a new ichnospecies (trace fossils like footprints receive their own taxonomic designations, known as ichnospecies). 

Fossils

These fossils represent some of the very last animals known to have inhabited the main Karoo Basin before it was overwhelmed by lava. Since the sandstone preserving these footprints was deposited between lava flows, this indicates that a variety of animals survived in the area even after volcanic activity had begun and the region was transformed into a “land of fire.” The authors suggest that further research to uncover more fossils and refine the dating of local rock layers has the potential to provide invaluable data on how local ecosystems responded to intense environmental stress at the onset of a global mass extinction. 

Bordy adds: “The fossil footprints were discovered within a thick pile of ancient basaltic lava flows that are ~183 million years old. The fossil tracks tell a story from our deep past on how continental ecosystems could co-exist with truly giant volcanic events that can only be studied from the geological record, because they do not have modern equivalents, although they can occur in the future of the Earth.”

What Is An Endangered Species?

Gray wolves, like this pair on Isle Royale, are listed as endangered in the United States.

Credit: Michigan Tech

By John Vucetich, professor, College of Forest Resources and Environmental Science

Lions and leopards are endangered species. Robins and raccoons clearly are not. The distinction seems simple until one ponders a question such as: How many lions would there have to be and how many of their former haunts would they have to inhabit before we’d agree they are no longer endangered?

To put a fine point on it, what is an endangered species? The quick answer: An endangered species is at risk of extinction. Fine, except questions about risk always come in shades and degrees, more risk and less risk.

Extinction risk increases as a species is driven to extinction from portions of its natural range. Most mammal species have been driven to extinction from half or more of their historic range because of human activities. 

The query “What is an endangered species?” is quickly transformed into a far tougher question: How much loss should a species endure before we agree that the species deserves special protections and concerted effort for its betterment? My colleagues and I put a very similar question to nearly 1,000 (representatively sampled) Americans after giving them the information in the previous paragraph. The results, “What is an endangered species?: judgments about acceptable risk,” are published today in Environmental Research Letters.

Three-quarters of those surveyed said a species deserves special protections if it had been driven to extinction from any more than 30% of its historic range. Not everyone was in perfect agreement. Some were more accepting of losses. The survey results indicate that people more accepting of loss were less knowledgeable about the environment and self-identify as advocates for the rights of gun and land owners. Still, three-quarters of people from the group of people who were more accepting of loss thought special protections were warranted if a species had been lost from more than 41% of their former range.

These attitudes of the American public are aligned with the language of the U.S. Endangered Species Act — the law for preventing species endangerment in the U.S. That law defines an endangered species as one that is “in danger of extinction throughout all or a significant portion of its range.”

But there might be a problem

Government decision-makers have tended to agree with the scientists they consult in judging what counts as acceptable risk and loss. These scientists express the trigger point for endangerment in very different terms. They tend to say a species is endangered if its risk of total and complete extinction exceeds 5% over 100 years.

Before human activities began elevating extinction risk, a typical vertebrate species would have experienced an extinction risk of 1% over a 10,000-year period. The extinction risk that decision-makers and their consultant experts have tended to consider acceptable (5% over 100 years) corresponds to an extinction risk many times greater that the extinction risk we currently impose on biodiversity! Experts and decision-makers — using a law designed to mitigate the biodiversity crisis — tend to allow for stunningly high levels of risk. But the law and the general public seem accepting of only lower risk that would greatly mitigate the biodiversity crisis. What’s going on?

One possibility is that experts and decision-makers are more accepting of the risks and losses because they believe greater protection would be impossibly expensive. If so, the American public may be getting it right, not the experts and decision-makers. Why? Because the law allows for two separate judgements. The first judgement is, is the species endangered and therefore deserving of protection? The second judgment is, can the American people afford that protection? Keeping those judgements separate is vital because making a case that more funding and effort is required to solve the biodiversity crisis is not helped by experts and decision-makers when they grossly understate the problem — as they do when they judge endangerment to entail such extraordinarily high levels of risk and loss.

Facts and Values

Another possible explanation for the judgments of experts and decision-makers was uncovered in an earlier paper led by Jeremy Bruskotter of Ohio State University (also a collaborator on this paper). They showed that experts tended to offer judgments about grizzly bear endangerment — based not so much their own independent expert judgement — but on basis of what they think (rightly or wrongly) their peers’ judgement would be.

Regardless of the explanation, a good answer to the question, “What an endangered species?” is an inescapable synthesis of facts and values. Experts on endangered species have a better handle on the facts than the general public. However, there is cause for concern when decision-makers do not reflect the broadly held values of their constituents. An important possible explanation for this discrepancy in values is the influence of special interests on decision-makers and experts charged with caring for biodiversity.  

Getting the answer right is of grave importance. If we do not know well enough what an endangered species is, then we cannot know well enough what it means to conserve nature, because conserving nature is largely — either directly or indirectly — about giving special care to endangered species until they no longer deserve that label.

Research collaborators include Jeremy T. Bruskotter of Ohio State University, Adam Feltz of University of Oklahoma, and Tom Offer-Westort also of University of Oklahoma.

Dinosaur Embryos

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.

Credit: © AMNH/M. Ellison
This is a photo of a hatchling Protoceratops andrewsi fossil from the Gobi Desert Ukhaa Tolgod, Mongolia.

“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.”

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.”

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.

“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.

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)

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

Researchers learn more about teen-age T.Rex

Photo by Mike on Pexels.com

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.

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.”

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.”

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.

“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.

Paleontologists discover complete Saurornitholestes langstoni specimen

Illustration by Jan Sovak

Discovery provides valuable insight into evolution of theropod dinosaurs around the world

A small, feathered theropod dinosaur, Saurornitholestes langstoni was long thought to be so closely related to Velociraptor mongoliensis that some researchers called it Velociraptor langstoni — until now.

The discovery of a nearly complete dromaeosaurid Saurornitholestes langstoni specimen is providing critical information for the evolution of theropod dinosaurs, according to new research by a University of Alberta paleontologist.

The 76-million-year-old species was long thought to be so closely related to Velociraptor from Mongolia that some researchers even called it Velociraptor langstoni–until now.

The landmark discovery was made by world-renowned paleontologists Philip Currie and Clive Coy from the University of Alberta and David Evans, James and Louise Temerty Endowed Chair of Vertebrate Palaeontology at the Royal Ontario Museum. The research illustrates how Saurornitholestes differs from Velociraptor. Importantly, the research also identifies a unique tooth evolved for preening feathers and provides new evidence that the dromaeosaurid lineage from North America that includes Saurornitholestes is distinct from an Asian lineage that includes the famous Velociraptor.

“Palaeontology in general is a gigantic puzzle where most of the pieces are missing. The discovery and description of this specimen represents the recovery of many pieces of the puzzle,” said Currie, professor in the Department of Biological Sciences and Canada Research Chair in Dinosaur Paleobiology. “This ranks in the top discoveries of my career. It is pretty amazing.”

Another piece of the puzzle

Saurornitholestes is a small, feathered carnivorous dinosaur within the dromaeosaurid family (also known as “raptors”) that was previously known from fragmentary remains. Discovered by Coy in Dinosaur Provincial Park in 2014, the new skeleton is remarkably complete and exquisitely preserved, with all the bones (except for the tail) preserved in life position. The new research, which focuses on the skull, shows that the North American form has a shorter and deeper skull than the Velociraptor. At the front of the skull’s mouth, the researchers also discovered a flat tooth with long ridges, which was likely used for preening feathers. The same tooth has since been identified in Velociraptor and other dromaeosaurids.

“Because of their small size and delicate bones, small meat-eating dinosaur skeletons are exceptionally rare in the fossil record. The new skeleton is by far the most complete and best-preserved raptor skeleton ever found in North America. It’s a scientific goldmine,” said Evans.

The study also establishes a distinction between dromaeosaurids in North America and Asia. “The new anatomical information we have clearly shows that the North American dromaeosaurids are a separate lineage from the Asian dromaeosaurids, although they do have a common ancestor,” said Currie. “This changes our understanding of intercontinental movements of these animals and ultimately will help us understand their evolution.”

Future research will investigate the remainder of the skeleton as well as additional analyses on the relationships between dromaeosaurids.

The paper, “Cranial Anatomy of New Specimens of Saurornitholestes langstoni (Dinosauria, Theropoda, Dromaeosauridae) from the Dinosaur Park Formation (Campanian) of Alberta,” was published in The Anatomical Record (doi: 10.1002/ar.24241).

Dinosaur-Era Shark Fossil Discovered in Kansas

Credit: (Image provided by Kenshu Shimada/DePaul University and Sternberg Museum of Natural History)

The shark is estimated to be nearly 17 feet or over 5 meters long

CHICAGO — A 91-million-year-old fossil shark newly named Cretodus houghtonorum discovered in Kansas joins a list of large dinosaur-era animals. Preserved in sediments deposited in an ancient ocean called the Western Interior Seaway that covered the middle of North America during the Late Cretaceous period (144 million to 66 million years ago), Cretodus houghtonorum was an impressive shark estimated to be nearly 17 feet or slightly more than 5 meters long based on a new study appearing in the Journal of Vertebrate Paleontology.

The fossil shark was discovered and excavated in 2010 at a ranch near Tipton, Kansas, in Mitchell County by researchers Kenshu Shimada and Michael Everhart and two central Kansas residents, Fred Smith and Gail Pearson. Shimada is a professor of paleobiology at DePaul University in Chicago. He and Everhart are both adjunct research associates at the Sternberg Museum of Natural History, Fort Hays State University in Hays, Kansas. The species name houghtonorum is in honor of Keith and Deborah Houghton, the landowners who donated the specimen to the museum for science.

Although a largely disarticulated and incomplete skeleton, it represents the best Cretodus specimen discovered in North America, according to Shimada. The discovery consists of 134 teeth, 61 vertebrae, 23 placoid scales and fragments of calcified cartilage, which when analyzed by scientists provided a vast amount of biological information about the extinct shark. Besides its estimated large body size, anatomical data suggested that it was a rather sluggish shark, belonged to a shark group called Lamniformes that includes modern-day great white and sand tiger sharks as distant cousins, and had a rather distinct tooth pattern for a lamniform shark, the researchers said.

“Much of what we know about extinct sharks is based on isolated teeth, but an associated specimen representing a single shark individual like the one we describe provides a wealth of anatomical information that in turn offers better insights into its ecology,” said Shimada, the lead author on the study.

“As important ecological components in marine ecosystems, understanding about sharks in the past and present is critical to evaluate the roles they have played in their environments and biodiversity through time, and more importantly how they may affect the future marine ecosystem if they become extinct,” he said.

During the excavation, Shimada and Everhart believed they had a specimen of Cretodus crassidens, a species originally described from England and subsequently reported commonly from North America. However, not even a single tooth matched the tooth shape of the original Cretodus crassidens specimen or any other known species of Cretodus, Shimada said.

“That’s when we realized that almost all the teeth from North America previously reported as Cretodus crassidens belong to a different species new to science,” he noted.

The growth model of the shark calibrated from observed vertebral growth rings indicates that the shark could have theoretically reached up to about 22 feet (about 6.8 meters).

“What is more exciting is its inferred large size at birth, almost 4 feet or 1.2 meters in length, suggesting that the cannibalistic behavior for nurturing embryos commonly observed within the uteri of modern female lamniforms must have already evolved by the late Cretaceous period,” Shimada added.

Furthermore, the Cretodus houghtonorum fossil intriguingly co-occurred with isolated teeth of another shark, Squalicorax, as well as with fragments of two fin spines of a yet another shark, a hybodont shark, the researchers said.

“Circumstantially, we think the shark possibly fed on the much smaller hybodont and was in turn scavenged by Squalicorax after its death,” said Everhart.

Discoveries like this would not be possible without the cooperation and generosity of local landowners, and the local knowledge and enthusiasm of amateur fossil collectors, according to the authors.

“We believe that continued cooperation between paleontologists and those who are most familiar with the land is essential to improving our understanding of the geologic history of Kansas and Earth as a whole,” said Everhart.

The new study, “A new large Late Cretaceous lamniform shark from North America with comments on the taxonomy, paleoecology, and evolution of the genus Cretodus,” will appear in the forthcoming issue of the Journal of Vertebrate Paleontology and is online at https://doi.org/10.1080/02724634.2019.1673399.

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Sources:
Kenshu Shimada
kshimada@depaul.edu
773-325-3697

Michael J. Everhart
mike@oceansofkansas.com
316-788-1354

Media Contact:
Russell Dorn
rdorn@depaul.edu
312-362-7128

Animals can lie to themselves too

Like Humans, Crayfish Talk a Tough Game

Self-deception like this seems very human. Now, thanks to a recent study led by an Arizona State University biologist, for the first time we know that it happens in the animal kingdom, too.

Crayfish are some of the most aggressive creatures on earth. They fight with big claws capable of doing real damage. But sometimes there’s not much muscle under the bravado.

“What males are doing is making as little crappy muscle as possible, which is energetically saving,” said Michael Angilletta, a biology professor in the School of Life Sciences.

It’s like buying designer knockoffs. You save a lot of money, and most people can’t tell the difference. In the case of crayfish, you make a big claw without much muscle, and you put crappy muscle on it to boot. Everyone sees you wave your big claw and they presume that you’re a powerful crayfish.

“Since they signal to each other before fighting, this is a way they can convince someone to back down without fighting,” Angilletta said. “Importantly, this only works if there’s enough crayfish out there that have big claws that are actually strong. If you accidentally fight one of those and call a bluff, you’re going to lose a claw.”

In the crayfish world, losing a claw is a disaster: It takes up to two years for a claw to regenerate. In the meantime, no one is mating with anyone who has a puny claw. 

Angilletta and his co-authors have been studying self-deception in crayfish for about 10 years. In 2006 they accidentally discovered that many crayfish with big claws were quite weak. There was about a tenfold variation.

“You would go, ‘Oh, this (pinch) is going to hurt,’ but it doesn’t hurt at all,” Angilletta said. “The question is are they not trying, or are they really not strong? And it’s repeatable from day after day with the same individuals.”

They combined mathematical modeling with an experiment to show that crayfish meet the criteria for self-deception. This approach opens up the possibility of studying self-deception in nonhuman animals, without being able to talk to them. They used 97 adult males, staging fights between 20 select crayfish and 77 opponents.

“How do we know what a crayfish would do if it knows whether it’s weak or it’s strong?” Angilletta asked. “If it knows that (it has a weak claw), it should actually be less aggressive.”

It might escalate up to the point of a fight, and then run away. The probability that a crayfish engaged in a fight depended on two factors: the relative size of its claws and the expected difference in force. How do they know how strong (or not) they are? Crayfish use claws to deter predators, defend territory and capture prey. They have a pretty good idea of how strong their own claws are. They’re also skilled at assessing their size versus an opponent’s. They can even recognize previous opponents.

So natural selection has given them an ability to detect size and identity. Given that they have those abilities, it naturally follows that they have an ability to gauge strength when knowing it will improve decisions.

“In our population of crayfish, deceptive signalers largely ignored their own strength when escalating or evading aggression,” Angilletta said. “If this benefit of heightened aggression outweighs any long-term cost, natural selection should favor individuals who escalate aggression through self-deception.”

In other words, they buy into their own bluff. Angilletta teaches a biology course on human behavior called “Why people steal, cheat, and lie,” which explores the ecological and evolutionary causes of selfishness and cooperation in human societies.

“What’s new about this study is that if you’re ever in a situation where I’m lying to you, there’s also a possibility I’m selling my lie exceptionally well because I’ve convinced myself that it’s true,” he said. “That’s because of self-deception. It’s very common in psychology but it’s not really that much in biology because we’re usually thinking about nonhuman animals and we don’t know what they’re thinking. We have a hard time understanding what they know and don’t know.”

The paper was published last summer in Behavioral Ecology.

Video Credits:  Ken Fagan, ASU

Photo Credit: Charlie Leight, ASU

About ASU

Arizona State University has developed a new model for the American Research University, creating an institution that is committed to access, excellence and impact. ASU measures itself by those it includes, not by those it excludes. As the prototype for a New American University, ASU pursues research that contributes to the public good, and ASU assumes major responsibility for the economic, social and cultural vitality of the communities that surround it.