These beetles have successfully freeloaded for 100 million years
Almost 100 million years ago, a tiny and misfortunate beetle died after wandering into a sticky glob of resin leaking from a tree in a region near present-day Southeast Asia. Fossilized in amber, this beetle eventually made its way to the desk of entomologist Joe Parker, assistant professor of biology and biological engineering at Caltech. Parker and his colleagues have now determined that the perfectly preserved beetle fossil is the oldest-known example of an animal in a behaviorally symbiotic relationship.
A paper describing the work appears on April 16 in the journal eLife.
Symbiotic relationships between two species have arisen repeatedly during animal evolution. These relationships range from mutually beneficial associations, like humans and their pet dogs, to the parasitic, like a tapeworm and its host.
Some of the most complex examples of behavioral symbiosis occur between ants and other types of small insects called myrmecophiles — meaning “ant lovers.” Thanks to ants’ abilities to form complex social colonies, they are able to repel predators and amass food resources, making ant nests a highly desirable habitat. Myrmecophiles display elaborate social behaviors and chemical adaptations to deceive ants and live among them, reaping the benefits of a safe environment and plentiful food.
Ants’ social behaviors first appear in the fossil record 99 million years ago, during the Cretaceous period of the Mesozoic era, and are believed to have evolved not long before, in the Early Cretaceous. Now, the discovery of a Cretaceous myrmecophile fossil implies that the freeloading insects were already taking advantage of ants’ earliest societies. The finding means that myrmecophiles have been a constant presence among ant colonies from their earliest origins and that this socially parasitic lifestyle can persist over vast expanses of evolutionary time.
“This beetle-ant relationship is the most ancient behavioral symbiosis now known in the animal kingdom,” says Parker. “This fossil shows us that symbiosis can be a very successful long-term survival strategy for animal lineages.”
The fossilized beetle, named Promyrmister kistneri, belongs to a subfamily of “clown” beetles (Haeteriinae), all modern species of which are myrmecophiles. These modern beetles are so specialized for life among ants that they will die without their ant hosts and have evolved extreme adaptations for infiltrating colonies. The beetles are physically well protected by a thick tank-like body plan and robust appendages, and they can mimic their host ants’ nest pheromones, allowing them to disguise themselves in the colony. They also secrete compounds that are thought to be pacifying or attractive to ants, helping the beetles gain the acceptance of their aggressive hosts. The fossilized Promyrmister is a similarly sturdy insect, with thick legs, a shielded head, and glandular orifices that the researchers theorize exuded chemicals to appease its primitive ant hosts.
Depending on another species so heavily for survival has its risks; indeed, an extinction of the host species would be catastrophic for the symbiont. The similarities between the fossilized beetle and its modern relatives suggest that the particular adaptations of myrmecophile clown beetles first evolved inside colonies of early “stem group” ants, which are long extinct. Due to Promyrmister’s remarkable similarity to modern clown beetles, Parker and his collaborators infer that the beetles must have “host switched” to colonies of modern ants to avoid undergoing extinction themselves. This adaptability of symbiotic organisms to move between partner species during evolution may be essential for the long-term stability of these intricate interspecies relationships.
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Fossils found in museum drawer in Kenya belong to gigantic carnivore
Paleontologists at Ohio University have discovered a new species of meat-eating mammal larger than any big cat stalking the world today. Larger than a polar bear, with a skull as large as that of a rhinoceros and enormous piercing canine teeth, this massive carnivore would have been an intimidating part of the eastern African ecosystems occupied by early apes and monkeys.
In a new study published in the Journal of Vertebrate Paleontology, the researchers name Simbakubwa kutokaafrika, a gigantic carnivore known from most of its jaw, portions of its skull, and parts of its skeleton. The 22-million-year-old fossils were unearthed in Kenya decades ago as researchers canvassed the region searching for evidence of ancient apes. Specimens were placed in a drawer at the National Museums of Kenya and not given a great deal of attention until Ohio University researchers Dr. Nancy Stevens and Dr. Matthew Borths rediscovered them, recognizing their significance.
“Opening a museum drawer, we saw a row of gigantic meat-eating teeth, clearly belonging to a species new to science,” says study lead author Borths. Borths was a National Science Foundation Postdoctoral Research Fellow with Stevens in the Department of Biomedical Sciences at Ohio University when the research was conducted, and is now Curator of the Division of Fossil Primates at the Duke Lemur Center at Duke University.
Simbakubwa is Swahili for “big lion” because the animal was likely at the top of the food chain in Africa, as lions are in modern African ecosystems. Yet Simbakubwa was not closely related to big cats or any other mammalian carnivore alive today. Instead, the creature belonged to an extinct group of mammals called hyaenodonts.
Hyaenodonts were the first mammalian carnivores in Africa. For about 45 million years after the extinction of the non-avian dinosaurs, hyaenodonts were the apex predators in Africa. Then, after millions of years of near-isolation, tectonic movements of the Earth’s plates connected Africa with the northern continents, allowing floral and faunal exchange between landmasses. Around the time of Simbakubwa, the relatives of cats, hyenas, and dogs began to arrive in Africa from Eurasia.
As the relatives of cats and dogs were going south, the relatives of Simbakubwa were going north. “It’s a fascinating time in biological history,” Borths says. “Lineages that had never encountered each other begin to appear together in the fossil record.”
The species name, kutokaafrika, is Swahili for “coming from Africa” because Simbakubwa is the oldest of the gigantic hyaenodonts, suggesting this lineage of giant carnivores likely originated on the African continent and moved northward to flourish for millions of years.
Ultimately, hyaenodonts worldwide went extinct. Global ecosystems were changing between 18 and 15 million years ago as grasslands replaced forests and new mammalian lineages diversified. “We don’t know exactly what drove hyaenodonts to extinction, but ecosystems were changing quickly as the global climate became drier. The gigantic relatives of Simbakubwa were among the last hyaenodonts on the planet,” remarks Borths.
“This is a pivotal fossil, demonstrating the significance of museum collections for understanding evolutionary history,” notes Stevens, Professor in the Heritage College of Osteopathic Medicine at Ohio University and co-author of the study. “Simbakubwa is a window into a bygone era. As ecosystems shifted, a key predator disappeared, heralding Cenozoic faunal transitions that eventually led to the evolution of the modern African fauna.”
This study was funded by grants from the National Science Foundation (EAR/IF-0933619; BCS-1127164; BCS-1313679; EAR-1349825; BCS-1638796; DBI-1612062), The Leakey Foundation, National Geographic Society (CRE), Ohio University Research Council, Ohio University Heritage College of Osteopathic Medicine, SICB and The Explorers Club.
This discovery underscores both the importance of supporting innovative uses of fossil collections, as well as the importance of supporting the research and professional development of talented young postdoctoral scientists like Dr. Borths,” said Daniel Marenda, a program director at the National Science Foundation, which funded this research. “This work has the potential to help us understand how species adapt — or fail to adapt in this case — to a rapidly changing global climate.”
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Ancient ‘Texas Serengeti’ had elephant-like animals, rhinos, alligators and more
During the Great Depression, some unemployed Texans were put to work as fossil hunters. The workers retrieved tens of thousands of specimens that have been studied in small bits and pieces while stored in the state collections of The University of Texas at Austin for the past 80 years.
Now, decades after they were first collected, a UT researcher has studied and identified an extensive collection of fossils from dig sites near Beeville, Texas, and found that the fauna make up a veritable “Texas Serengeti” — with specimens including elephant-like animals, rhinos, alligators, antelopes, camels, 12 types of horses and several species of carnivores. In total, the fossil trove contains nearly 4,000 specimens representing 50 animal species, all of which roamed the Texas Gulf Coast 11 million to 12 million years ago.
A paper describing these fossils, their collection history and geologic setting was published April 11 in the journal Palaeontologia Electronica.
“It’s the most representative collection of life from this time period of Earth history along the Texas Coastal Plain,” said Steven May, the research associate at the UT Jackson School of Geosciences who studied the fossils and authored the paper.
In addition to shedding light on the inhabitants of an ancient Texas ecosystem, the collection is also valuable because of its fossil firsts. They include a new genus of gomphothere, an extinct relative of elephants with a shovel-like lower jaw, and the oldest fossils of the American alligator and an extinct relative of modern dogs.
The fossils came into the university’s collection as part of the State-Wide Paleontologic-Mineralogic Survey that was funded by the Works Progress Administration (WPA), a federal agency that provided work to millions of Americans during the Great Depression. From 1939 to 1941, the agency partnered with the UT Bureau of Economic Geology, which supervised the work and organized field units for collecting fossils and minerals across the state.
Despite lasting only three years, the survey found and excavated thousands of fossils from across Texas including four dig sites in Bee and Live Oak counties, with the majority of their finds housed in what is now the Texas Vertebrate Paleontology Collections at the Jackson School Museum of Earth History. Over the years, a number of scientific papers have been published on select groups of WPA specimens. But May’s paper is the first to study the entire fauna.
This extensive collection of fossils is helping to fill in gaps about the state’s ancient environment, said Matthew Brown, the director of the museum’s vertebrate paleontology collections.
The emphasis on big mammals is due in large part to the collection practices of the fossil hunters, most of whom were not formally trained in paleontology. Large tusks, teeth and skulls were easier to spot — and more exciting to find — than bones left by small species.
“They collected the big, obvious stuff,” May said. “But that doesn’t fully represent the incredible diversity of the Miocene environment along the Texas Coastal Plain.”
In order to account for gaps in the collection, May tracked down the original dig sites so he could screen for tiny fossils such as rodent teeth. One of the sites was on a ranch near Beeville owned by John Blackburn. Using aerial photography and notes from the WPA program stored in the university’s archives, May and the research team were able to track down the exact spot of an original dig site.
“We’re thrilled to be a part of something that was started in 1939,” Blackburn said. “It’s been a privilege to work with UT and the team involved, and we hope that the project can help bring additional research opportunities.”
Scores of WPA-era fossils in the UT collections are still secured in plaster field jackets, waiting to be unpacked for future research projects. Lab managers Deborah Wagner and Kenneth Bader are supervising their preparation, which includes teaching UT students fossil prep skills so they can pick up where the WPA workers left off.
Wagner said that the advantage of unpacking fossils decades later is that they are able to apply modern research techniques that scientists from past eras wouldn’t have dreamed possible.
“We are able to preserve more detailed anatomy and answer questions that require higher resolution data,” she said.
May said that he plans to continue to study the fossils as more are prepared.
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‘Cthulhu’ fossil reconstruction reveals monstrous relative of modern sea cucumbers
An exceptionally-preserved fossil from Herefordshire in the UK has given new insights into the early evolution of sea cucumbers, the group that includes the sea pig and its relatives, according to a new article published today in the journal Proceedings of the Royal Society B.
Palaeontologists from the UK and USA created an accurate 3D computer reconstruction of the 430 million-year-old fossil which allowed them to identify it as a species new to science. They named the animal Sollasina cthulhu due to its resemblance to monsters from the fictional Cthulhu universe created by author H.P. Lovecraft.
Although the fossil is just 3 cm wide, its many long tentacles would have made it appear quite monstrous to other small sea creatures alive at the time. It is thought that these tentacles, or ‘tube feet’, were used to capture food and crawl over the seafloor.
Like other fossils from Herefordshire, Sollasina cthulhu was studied using a method that involved grinding it away, layer-by-layer, with a photograph taken at each stage. This produced hundreds of slice images, which were digitally reconstructed as a ‘virtual fossil’.
This 3D reconstruction allowed palaeontologists to visualise an internal ring, which they interpreted as part of the water vascular system — the system of fluid-filled canals used for feeding and movement in living sea cucumbers and their relatives.
Lead author, Dr Imran Rahman, Deputy Head of Research at Oxford University Museum of Natural History said:
“Sollasina belongs to an extinct group called the ophiocistioids, and this new material provides the first information on the group’s internal structures. This includes an inner ring-like form that has never been described in the group before. We interpret this as the first evidence of the soft parts of the water vascular system in ophiocistioids.”
The new fossil was incorporated into a computerized analysis of the evolutionary relationships of fossil sea cucumbers and sea urchins. The results showed that Sollasina and its relatives are most closely related to sea cucumbers, rather than sea urchins, shedding new light on the evolutionary history of the group.
Co-author Dr Jeffrey Thompson, Royal Society Newton International Fellow at University College London, said:
“We carried out a number of analyses to work out whether Sollasina was more closely related to sea cucumbers or sea urchins. To our surprise, the results suggest it was an ancient sea cucumber. This helps us understand the changes that occurred during the early evolution of the group, which ultimately gave rise to the slug-like forms we see today.”
The fossil was described by an international team of researchers from Oxford University Museum of Natural History, University of Southern California, Yale University, University of Leicester, and Imperial College London. It represents one of many important finds recovered from the Herefordshire fossil site in the UK, which is famous for preserving both the soft as well as the hard parts of fossils.
The fossil slices and 3D reconstruction are housed at Oxford University Museum of Natural History.
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First-confirmed occurrence of a lambeosaurine dinosaur found on Alaska’s North Slope
Paleontologists from Hokkaido University in Japan, in cooperation with paleontologists from the Perot Museum of Nature and Science in Dallas, Texas, have discovered the first-confirmed occurrence of a lambeosaurine (crested ‘duck-billed’ dinosaur) from the Arctic — part of the skull of a lambeosaurine dinosaur from the Liscomb Bonebed (71-68 Ma) found on Alaska’s North Slope. The bonebed was previously known to be rich in hadrosaurine hadrosaurids (non-crested ‘duck-billed’ dinosaurs).
The discovery proves for the first time that lambeosaurines inhabited the Arctic during the Late Cretaceous. In addition, the numeric abundance of hadrosaurine fossils compared to the lambeosaurine fossils in the marine-influenced environment of the Liscomb Bonebed suggests the possibility that hadrosaurines and lambeosaurines had different habitat preferences.
The paleontologists’ findings were published today in Scientific Reports, an open-access, multi-disciplinary journal from Nature Research dedicated to constructive, inclusive and rigorous peer review. The paper — entitled “The first definite lambeosaurine bone from the Liscomb Bonebed of the Upper Cretaceous Prince Creek Formation, Alaska, United States” — is co-authored by Yoshitsugu Kobayashi, Ph.D., and Ryuji Takasaki, of Hokkaido University, in cooperation with Anthony R. Fiorillo, Ph.D., of the Perot Museum of Nature and Science. Other authors are Ronald Tykoski, Ph.D. of the Perot Museum and Paul McCarthy, Ph.D., of the University of Alaska.
“This new discovery illustrates the geographic link between lambeosaurines of North America and the Far East,” said Takasaki. “Hopefully, further work in Alaska will reveal how closely the dinosaurs of Asia and North America are connected.”
The newly discovered fossil, which is housed in the collections of the Perot Museum of Nature and Science, is a supraoccipital, one of the bones that forms the braincase. The new supraoccipital differs from those of hadrosaurines by the presence of large supraoccipital bosses and it’s short, front-to-back length. Since these features are commonly seen in other members of Lambeosaurinae, the newly discovered supraoccipital was assigned to that group.
“This first definitive evidence of a crested hadrosaur in the Cretaceous Arctic tells us that we still have much to learn about the biodiversity and the biologically productive environments of the ancient north, and that the story these fossils tell us is continually evolving,” adds Dr. Fiorillo.
Background. The Arctic is an extreme environment that is low in temperature, lacks sunlight during winters, and has seasonally limited food resources. Though it was warmer during the Late Cretaceous, the Arctic was surely one of the most challenging places to live for large vertebrates at the time. The Prince Creek Formation on the North Slope of Alaska is a world-famous rock unit for studying dinosaurs of the ancient Arctic. Because the dinosaurs found there lived in the ancient Arctic, rather than tropical or sub-tropical conditions, these dinosaurs challenge much of what we think we know about dinosaurs. The Liscomb Bonebed (71-68 Ma), which was deposited near the ancient Arctic shoreline, is especially rich in dinosaur bones, with more than 6,000 bones collected from it thus far.
More than 99% of dinosaur fossils known from the Liscomb Bonebed are hadrosaurs, a group of large, duck-billed herbivorous dinosaurs who lived during the Late Cretaceous and were found throughout much of the northern hemisphere. All of the hadrosaur fossils from the Liscomb Bonebed were long considered to belong to a hadrosaurine duck-billed dinosaur called Edmontosaurus. Up until now, all of the hadrosaurids known from across the Arctic, including those from the Liscomb Bonebed, were considered to belong to crest-less hadrosaurines.
The discovery of a fossil from a lambeosaurine hadrosaurid in the Liscomb Bonebed is historically important for Japanese paleontologists. The first “Japanese” dinosaur, Nipponosaurus, is a lambeosaurine hadrosaur. Based on the new discovery, Hokkaido University and the Perot Museum together used this discovery to further investigate the ecology of the Arctic hadrosaurids.
Significance
1. The first Arctic lambeosaurine: The new discovery indicates Arctic inhabitance and adaptation of lambeosaurines for the first time. In addition, the fossil’s morphological similarities to the same bone in the skull of southern Canadian lambeosaurines suggest faunal interactions between the Arctic and the mid-latitudes.
2. Implication on habitat preferences: While the Liscomb Bonebed is known for numerous hadrosaurine fossils, the newly discovered bone represents the only definite lambeosaurine fossil from the site. The same trend is also known in mid-latitude localities of North America and eastern Asia, which were also deposited in near-shore environments. On the other hand, more lambeosaurine fossils are found in deposits laid down in inland environments. Therefore, we hypothesize that lambeosaurines favored inland environments, while hadrosaurines preferred coastal environments, a trend likely to have been independent of latitude. Different habitat preferences might have been a strategy to avoid excessive competition between the two groups of ‘duck-billed’ dinosaurs.
Future plans
Although the new discovery reveals Arctic inhabitance by lambeosaurines, more specific taxonomic status and potential functional adaptations to the severe Arctic environment remain unknown due to incompleteness of the specimen. Additional excavation and further research will help answer these questions.
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Journal Reference:
- Ryuji Takasaki, Anthony R. Fiorillo, Yoshitsugu Kobayashi, Ronald S. Tykoski, Paul J. McCarthy. The First Definite Lambeosaurine Bone From the Liscomb Bonebed of the Upper Cretaceous Prince Creek Formation, Alaska, United States. Scientific Reports, March 29, 2019; DOI: 10.1038/s41598-019-41325-8