280 million-year-old fossil reveals origins of chimaeroid fishes

High-definition CT scans of the fossilized skull of a 280 million-year-old fish reveal the origin of chimaeras, a group of cartilaginous fish related to sharks. Analysis of the brain case of Dwykaselachus oosthuizeni, a shark-like fossil from South Africa, shows telltale structures of the brain, major cranial nerves, nostrils and inner ear belonging to modern-day chimaeras.

This discovery, published early online in Nature on Jan. 4, allows scientists to firmly anchor chimaeroids — the last major surviving vertebrate group to be properly situated on the tree of life — in evolutionary history, and sheds light on the early development of these fish as they diverged from their deep, shared ancestry with sharks.

“Chimaeroids belong somewhere close to the sharks and rays, but there’s always been uncertainty when you search deeper in time for their evolutionary branching point,” said Michael Coates, PhD, professor of organismal biology and anatomy at the University of Chicago, who led the study.

“Chimaeras are unusual throughout the long span of their fossil record,” Coates said. “Because of this, it’s been difficult to understand how they got to be the way they are in the first place. This discovery sheds new light not only on the early evolution of shark-like fishes, but also on jawed vertebrates as a whole.”

Chimaeras include about 50 living species, known in various parts of the world as ratfish, rabbit fish, ghost sharks, St. Joseph sharks or elephant sharks. They represent one of four fundamental divisions of modern vertebrate biodiversity. With large eyes and tooth plates adapted for grinding prey, these deep-water dwelling fish are far from the bloodthirsty killer sharks of Hollywood.

For more than 100 years, they have fascinated biologists. “There are few of the marine animals that on account of structure and relationships to other forms living and extinct have as great interest for zoologists and palaeontologists as the Chimaeroids,” wrote Harvard naturalist Samuel Garman in 1904. More than a century later, the relationship between chimaeras, the earliest sharks, and other early jawed fishes in the fossil record continues to puzzle paleontologists.

Chimaeras — named for their similarities to a mythical creature described by Homer as “lion-fronted and snake behind, a goat in the middle” — are unusual. Their anatomy comprises features reminiscent of sharks, ray-finned fishes and tetrapods, and their form is shaped by hardened bits of cartilage rather than bone. Because they are found in deep water, they were long considered rare. But as scientists gained the technology to explore more of the ocean, they are now known to be widespread, but their numbers remain uncertain.

After a 2014 study detailing their extremely slow-evolving genomes was published in Nature, interest in chimaeras blossomed. Of all living vertebrates with jaws, chimaeras seemed to offer the best promise of finding an archive of information about conditions close to the last common ancestor of humans and a Great White.

Like sharks, also reliant on cartilage, chimaeras rarely fossilize. The few known early chimaera fossils closely resemble their living descendants. Until now, the chimaeroid evolutionary record consisted mostly of isolated specimens of their characteristic hyper-mineralized tooth plates.

The Dwykaselachus fossil resolves this issue. It was originally discovered by amateur paleontologist and farmer Roy Oosthuizen when he split open a nodule of rock on his farm in South Africa in the 1980s. An initial description named it based on material visible at the broken surface of the nodule. It was carefully archived in the South African Museum in Cape Town, where its splendor awaited technology able to unwrap its long-shrouded secrets.

In 2013, when the University of the Witwatersrand Evolutionary Studies Institute obtained a micro CT scanner, Dr. Robert Gess, a South African Centre of Excellence in Palaeosciences partner and co-author of this study, began scanning Devonian shark fossils while he was based at the Rhodes University Geology Department. Coates encouraged him to investigate Dwykaselachus.

At the surface, Dwykaselachus appeared to be a symmoriid shark, a bizarre group of 300+ million-year-old sharks, known for their unusual dorsal fin spines, some resembling boom-like prongs and others surreal ironing boards.

CT scans showed that the Dwykaselachus skull was remarkably intact, one of a very few that had not been crushed during fossilization. The scans also provide an unprecedented view of the interior of the brain case.

“When I saw it for the first time, I was stunned,” Coates said. “The specimen is remarkable.”

The images, one reviewer commented, are “almost dripping with data.”

They show a series of telltale anatomical structures that mark the specimen as an early chimaera, not a shark. The braincase preserves details about the brain shape, the paths of major cranial nerves and the anatomy of the inner ear. All of which indicate that Dwyka belongs to modern-day chimaeras. The scans reveal clues about how these fish began to diverge from their common ancestry with sharks.

A large extinction of vertebrates at the end of the Devonian period, about 360 million years ago, gave rise to an explosion of cartilaginous fishes. Instead of what became modern-day sharks, Coates said, revelations from this study indicate that “much of this new biodiversity was, instead, early chimaeras.”

“We can now say that the first radiation of cartilaginous fishes after the end Devonian extinction was chimaeras, in abundance.” Coates said. “It’s the inverse of what we’ve got today, where sharks are far more common.”

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How long did it take to hatch a dinosaur egg? 3-6 months

A human typically gives birth after nine months. An ostrich hatchling emerges from its egg after 42 days. But how long did it take for a baby dinosaur to incubate?

Groundbreaking research led by a Florida State University professor establishes a timeline of anywhere from three to six months depending on the dinosaur.

In an article in the Proceedings of the National Academy of Sciences, FSU Professor of Biological Science Gregory Erickson and a team of researchers break down the complicated biology of these prehistoric creatures and explain how embryonic dental records solved the mystery of how long dinosaurs incubated their eggs.

“Some of the greatest riddles about dinosaurs pertain to their embryology — virtually nothing is known,” Erickson said. “Did their eggs incubate slowly like their reptilian cousins — crocodilians and lizards? Or rapidly like living dinosaurs — the birds?”

Scientists had long theorized that dinosaur incubation duration was similar to birds, whose eggs hatch in periods ranging from 11-85 days. Comparable-sized reptilian eggs typically take twice as long — weeks to many months.

Because the eggs of dinosaurs were so large — some were about 4 kilograms or the size of a volleyball — scientists believed they must have experienced rapid incubation with birds inheriting that characteristic from their dinosaur ancestors.

Erickson, FSU graduate student David Kay and colleagues from University of Calgary and the American Museum of Natural History decided to put these theories to the test.

To do that, they accessed some rare fossils — those of dinosaur embryos.

“Time within the egg is a crucial part of development, but this earliest growth stage is poorly known because dinosaur embryos are rare,” said co-author Darla Zelenitsky, assistant professor of geoscience at University of Calgary. “Embryos can potentially tell us how dinosaurs developed and grew very early on in life and if they are more similar to birds or reptiles in these respects.”

The two types of dinosaur embryos researchers examined were those from Protoceratops — a sheep-sized dinosaur found in the Mongolian Gobi Desert whose eggs were quite small (194 grams) — and Hypacrosaurus, an enormous duck-billed dinosaur found in Alberta, Canada with eggs weighing more than 4 kilograms.

Erickson and his team ran the embryonic jaws through a CT scanner to visualize the forming dentition. Then, they extracted several of the teeth to further examine them under sophisticated microscopes.

Researchers found what they were looking for on those microscope slides. Growth lines on the teeth showed researchers precisely how long the dinosaurs had been growing in the eggs.

“These are the lines that are laid down when any animal’s teeth develops,” Erickson said. “They’re kind of like tree rings, but they’re put down daily. We could literally count them to see how long each dinosaur had been developing.”

Their results showed nearly three months for the tiny Protoceratops embryos and six months for those from the giant Hypacrosaurus.

“Dinosaur embryos are some of the best fossils in the world,” said Mark Norell, Macaulay Curator for the American Museum of Natural History and a co-author on the study. “Here, we used spectacular fossils specimens collected by American Museum expeditions to the Gobi Desert, coupled them with new technology and new ideas, leading us to discover something truly novel about dinosaurs.”

The implications of long dinosaur incubation are considerable.

In addition to finding that dinosaur incubation was similar to primitive reptiles, the researchers could infer many aspects of dinosaurian biology from the results.

Prolonged incubation put eggs and their parents at risk from predators, starvation and other environmental risk factors. And theories that some dinosaurs nested in the more temperate lower latitude of Canada and then traveled to the Arctic during the summer now seem unlikely given the time frame for hatching and migration.

The biggest ramification from the study, however, relates to the extinction of dinosaurs. Given that these warm-blooded creatures required considerable resources to reach adult size, took more than a year to mature and had slow incubation times, they would have been at a distinct disadvantage compared to other animals that survived the extinction event.

“We suspect our findings have implications for understanding why dinosaurs went extinct at the end of the Cretaceous period, whereas amphibians, birds, mammals and other reptiles made it through and prospered,” Erickson said.

This research was supported by the National Science Foundation.

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Fossilized water fleas: Evolution of the micro-crustacean group Cladocera

Scientists of the Senckenberg Institute have studied the evolutionary history of the so-called “water fleas.” These tiny crustaceans from the order Cladocera form the basis of the trophic pyramid and therefore play an important role in modern ecosystems. Due to the fact that they are rarely preserved as fossils, little is known about the water fleas’ evolution. In their study, which was recently published in the scientific journal “Earth-Science Reviews,” the team of scientists presents the first comprehensive inventory of all Cladocera fossils in an ecological context. The scientists show that the animals’ morphology has undergone very little change over the course of geological history. Nevertheless, the water fleas demonstrate a high adaptability to changes in environmental conditions.

A search for organisms in any lake or puddle will very likely turn up a representative of the Cladocera. With more than 700 species, these tiny animals — commonly referred to as “water fleas” due to their bouncing locomotion — inhabit almost all types of freshwater environments. “Despite this wealth of species and habitats, little is known about the evolutionary history of the Cladocera,” explains Dr. Kay Van Damme of the Senckenberg Research Institute in Frankfurt, and he continues, “Since the animals do not possess a calcareous shell or carapace, they are only rarely preserved as fossils.”

For the first time, Van Damme and his colleague, Prof. Alexey A. Kotov of the A.N. Severtsov Institute of Ecology and Evolution in Moscow, have now compiled a complete inventory of all known Cladocera species. “The Cladocera constitute a crucial group in our effort to understand the development of freshwater ecosystems throughout geological history,” says Van Damme in explanation of the team’s motivation. Even today, water fleas still form the basis of many food chains, which makes them an important component of aquatic ecosystems.

Moreover, the tiny crustaceans are very sensitive to environmental changes and can thus be used to monitor water quality — for years, the genus Daphnia has served as a model organism in this regard. “In addition, Daphnia is the first representative of the crustaceans whose genome has been published — therefore, water fleas play a similar role in aquatic environmental genomics as does the fruit fly Drosophila in terrestrial environments,” adds Van Damme.

According to the team of researchers, the first representatives of the water fleas appeared in the early Jurassic, about 180 million years ago. “Since then, the basic design of the Cladocera has hardly changed,” says the biologist from Frankfurt, and he continues, “Nevertheless, this ‘living fossil’ was able to adapt very well to a variety of different environmental conditions.” For example, the water fleas developed various defense mechanisms to escape predators. “Daphnia and company were even able to survive the massive extinction event at the Cretaceous/Tertiary boundary, which, among others, claimed all of the terrestrial dinosaurs,” says Van Damme in closing.

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Mammals in age of dinosaurs packed powerful bite

Move over, hyenas and saber-toothed cats; there’s a mammal with an even stronger bite. A new study by Burke Museum and University of Washington paleontologists describes an early marsupial relative called Didelphodon vorax that lived alongside ferocious dinosaurs and had, pound-for-pound, the strongest bite force of any mammal ever recorded.

Published in the journal Nature Communications, the team’s findings suggest mammals were more varied during the Age of Dinosaurs than previously believed. Didelphodon was able to eat a variety of foods, and was likely a scavenger-predator who could eat prey ranging from snails to small dinosaurs.

In addition, the team re-traced the origins of marsupials. Previous theories attribute South America as the origin of marsupials, but anatomical features of the Didelphodon point to marsupials originating in North America 10-20 million years earlier than originally thought, and later dispersing and diversifying in South America.

“What I love about Didelphodon vorax is that it crushes the classic mold of Mesozoic mammals,” Dr. Gregory P. Wilson, Burke Museum Adjunct Curator of Vertebrate Paleontology and University of Washington Associate Professor of Biology, said. “Instead of a shrew-like mammal meekly scurrying into the shadows of dinosaurs, this badger-sized mammal would’ve been a fearsome predator on the Late Cretaceous landscape — even for some dinosaurs.”

All of these findings are made possible by four fossil specimens recently discovered in the 69-66 million-year-old deposits of the Hell Creek Formation in Montana and North Dakota. Prior to these discoveries, the 60 known species of metatherians (marsupials and their closest relatives) from the Cretaceous of North America — including Didelphodon — were almost all identified through fragments of jaw bones or teeth, providing a limited glimpse into marsupials’ closest relatives. These four fossils include a nearly-complete skull from the North Dakota Geological Survey State Fossil collection, a partial snout and an upper jaw bone from the Burke Museum’s collections, and another upper jaw from the Sierra College Natural History Museum.

By analyzing never-before-seen parts of Didelphodon’s anatomy, Dr. Wilson and his colleagues were able to determine these marsupial relatives were about the size of today’s Virginia opossum and were the largest metatherian from the Cretaceous. With a nearly complete skull to measure, they were able to estimate the overall size of Didelphodon, which ranged from 5.3-11.5 pounds. To test the bite force of Didelphodon, Abby Vander Linden, a UW Biology research technician in Burke Museum Curator of Mammalogy Dr. Sharlene Santana’s lab and now a graduate student at University of Massachusetts Amherst, CT-scanned the fossils and compared the gaps in reconstructed skulls where jaw muscles would go to present-day mammals with known bite forces. Bite force measurements indicate that pound-for-pound, Didelphodon had the strongest bite force of any mammal that has ever lived. In addition to the bite force, Didelphodon’s canines were similar to living felines and hyenas — suggesting they could handle biting into bone, biting deep and killing prey. Its shearing molars and big rounded premolars, combined with powerful jaws and jaw muscles indicate it had a specific niche in the food web as a predator or scavenger capable of crushing hard bone or shells, and was capable of eating prey as big as it was — even possibly small dinosaurs.

“I expected Didelphodon to have a fairly powerful bite based on the robust skull and teeth, but even I was surprised when we performed the calculations and found that, when adjusted for body size, it was capable of a stronger pound-for-pound bite than a hyena,” Vander Linden said. “That’s a seriously tough mammal.”

Co-author Dr. Jonathan Calede, former UW Biology graduate student and now a visiting assistant professor at Bucknell University, also examined “microwear” patterns, or tiny pits and scratches on the specimens’ teeth, to indicate what the animals were eating as their “last suppers” (most likely one-to-two days before the animals died). By comparing the microwear patterns from Didelphodon to the teeth of other fossilized species and current-day mammals with known diets from the Burke’s mammal collection, Calede found Didelphodon was an omnivore that likely consumed a range of vertebrates, plants and hard-shelled invertebrates like molluscs and crayfish, but few insects, spiders and annelids (earthworms and leeches).

“The interesting thing about these fossils is that they allowed us to study the ecology of Didelphodon from many angles,” Calede said. “The strength of the conclusions come from the convergence of microwear with bite force analysis, studies of the shape and breakage of the teeth, as well as the shape of the skull as a whole.”

In addition to learning much more about the biology of Didelphodon, the newly-described skull features on these fossils provide clues that help clarify the origin of all marsupials. The team found five major lineages of marsupial ancestors and marsupials themselves diverged in North America 100-85 million years ago. Marsupial relatives also got larger and ate a wider variety of foods, coinciding with an increase in diversity of other early mammals and flowering plants. Most of this North American diversity was then lost gradually from the late Campanian to Maastrichtian (79-66 million-years-ago) and then abruptly during the Cretaceous-Palaeogene (66 million-years-ago) mass extinction that also killed all dinosaurs except birds. Around this time, marsupials’ diversity and evolution shifted to South America.

“Our study highlights how, despite decades of paleontology research, new fossil discoveries and new ways of analyzing those fossils can still fundamentally impact how we view something as central to us as the evolution of our own clade, mammals,” Dr. Wilson said.

Fossil pollen ‘sneeze’ caught by research team

Like capturing a sneeze, researchers including a University of Guelph scientist have recorded the only known example of prehistoric pollen caught in explosive mid-discharge from a fossil flower.

The team describes this “freeze-frame” fossilized pollen release — preserved in amber more than 20 million years ago — in a paper describing a new genus of fossil nettle plants.

The researchers captured on camera pollen explosions.

The paper is co-authored by Peter Kevan, emeritus professor in the School of Environmental Sciences. It appears in the journal Botany alongside another paper by a second team that also includes the U of G researcher.

That second paper looks at a modern-day plant relative in Latin America that is surprising researchers with its use of explosive pollen release, a fair-weather dispersal method seemingly ill-suited to its home in humid tropical rainforests.

In their fossil paper, Kevan and his co-authors describe a new genus (Ekrixanthera, meaning “explosive anther”) containing two new species of extinct plants related to modern-day nettles.

These fossil plants were preserved during the mid-Tertiary period, said Kevan. By then, dinosaurs were long-extinct and non-human mammals roamed Earth.

The samples came from the Dominican Republic and Mexico.

One Mexican sample has preserved pollen grains caught in mid-discharge from the male plant’s anther.

This pollen burst normally takes less than one-tenth of a second, said Kevan. “It’s remarkable that it was captured. It’s like catching a sneeze.”

He was asked to help identify the plants by lead author George Poinar Jr., an expert on amber fossils at Oregon State University.

“We ended up with the new genus because the flowers do not match those of any modern species,” said Kevan. “This tells us something about how old that group of plants is, and that this pollination mechanism goes back a long way.”

That form of pollen dispersal is also described in the second paper about modern-day tropical nettles. Boehmeria caudata grows from southern North America to northern Argentina.

Explosive pollen release is “something you don’t expect in the rainforest. Pollen blasted into the air is likely to get rained out.”

Most tropical plants rely instead on such creatures as insects, bats and birds rather than wind pollination, said Kevan.

In this group of nettles, the male plant disperses its pollen during short dry periods. Even during the rainy season, short sunny periods of high heat and low humidity trigger pollen release.

Drying causes parts of its stamens to shrink unevenly. Physical tension ruptures the anther to release an explosive burst of pollen.

That quick-release mechanism propels pollen into air currents and allows the male flowers to react to short-term weather conditions.

Kevan’s co-authors are students at the University of Sao Paulo led by Paula Maria Montoya-Pfeiffer. They studied Boehmeria during a pollination course taught in Brazil by Kevan in late 2014.

He and colleagues have taught that course in several Latin American countries for decades.

A rare small specimen discovered from the age of flying giants

A rare small-bodied pterosaur, a flying reptile from the Late Cretaceous period approximately 77 million years ago, is the first of its kind to have been discovered on the west coast of North America.

Pterosaurs are the earliest vertebrates known to have evolved powered flight.

The specimen is unusual as most pterosaurs from the Late Cretaceous were much larger with wingspans of between four and eleven metres (the biggest being as large as a giraffe, with a wingspan of a small plane), whereas this new specimen had a wingspan of only 1.5 metres.

The fossils of this animal are the first associated remains of a small pterosaur from this time, comprising a humerus, dorsal vertebrae (including three fused notarial vertebrae) and other fragments. They are the first to be positively identified from British Columbia, Canada and have been identified as belonging to an azhdarchoid pterosaur, a group of short-winged and toothless flying reptiles which dominated the final phase of pterosaur evolution.

Previous studies suggest that the Late Cretaceous skies were only occupied by much larger pterosaur species and birds, but this new finding, which is reported in the Royal Society journal Open Science, provides crucial information about the diversity and success of Late Cretaceous pterosaurs.

Lead author of the study Elizabeth Martin-Silverstone, a Palaeobiology PhD Student at the University of Southampton, said: “This new pterosaur is exciting because it suggests that small pterosaurs were present all the way until the end of the Cretaceous, and weren’t outcompeted by birds. The hollow bones of pterosaurs are notoriously poorly preserved, and larger animals seem to be preferentially preserved in similarly aged Late Cretaceous ecosystems of North America. This suggests that a small pterosaur would very rarely be preserved, but not necessarily that they didn’t exist.”

The fossil fragments were found on Hornby Island in British Columbia in 2009 by a collector and volunteer from the Royal British Columbia Museum, who then donated them to the Museum. At the time, it was given to Victoria Arbour, a then PhD student and dinosaur expert at the University of Alberta. Victoria, as a postdoctoral researcher at North Carolina State University and the North Carolina Museum of Natural Sciences, then contacted Elizabeth and the Royal BC Museum sent the specimen for analysis in collaboration with Dr Mark Witton, a pterosaur expert at the University of Portsmouth.

Dr Witton said: “The specimen is far from the prettiest or most complete pterosaur fossil you’ll ever see, but it’s still an exciting and significant find. It’s rare to find pterosaur fossils at all because their skeletons were lightweight and easily damaged once they died, and the small ones are the rarest of all. But luck was on our side and several bones of this animal survived the preservation process. Happily, enough of the specimen was recovered to determine the approximate age of the pterosaur at the time of its death. By examining its internal bone structure and the fusion of its vertebrae we could see that, despite its small size, the animal was almost fully grown. The specimen thus seems to be a genuinely small species, and not just a baby or juvenile of a larger pterosaur type.”

Elizabeth Martin-Silverstone added: “The absence of small juveniles of large species — which must have existed — in the fossil record is evidence of a preservational bias against small pterosaurs in the Late Cretaceous. It adds to a growing set of evidence that the Late Cretaceous period was not dominated by large or giant species, and that smaller pterosaurs may have been well represented in this time. As with other evidence of smaller pterosaurs, the fossil specimen is fragmentary and poorly preserved: researchers should check collections more carefully for misidentified or ignored pterosaur material, which may enhance our picture of pterosaur diversity and disparity at this time.”

The benefits of commercial fossil sales to 21st-century paleontology

Authors: Peter L. Larson and Donna Russell

Article number: 17.1.2E
Published April 2014

The luckiest people on this planet are the ones that have also made their passion their career. This is equally true for vertebrate paleontologists and commercial fossil dealers. We have other things in common as well. We all agree that fossils are important. We agree that it is our responsibility to educate the public about fossils. And we agree that scientifically important specimens should be in museums.

Fossils have been collected, bartered, bought and sold for thousands of years (Mayor 2000). Commercialism has remained a crucial and functionally key element of paleontology throughout its history. Although all facets of paleontology are permeated with continuing scientific contributions by commercial entities (Manning 2001), this essay will only reference a few of the more notable.

In Europe, much of what we know about the Jurassic marine faunas and environments of the Posidonia Shale Lagerstätten of Holzmaden (Germany), and the Blue Lias of Lyme Regis, Dorset (England) are based upon collections made by people who sold fossils. Mary Anning, an iconic person in the field of paleontology, is one of the more famous commercial collectors. Academics and curators at British institutions accepted Anning as a colleague, despite her lack of a formal degree or position at a university (McGowan 2001, Emling 2009). A congenial and civilized working relationship still exists today in England between commercial “professional” collectors and museum and university academics (Manning 2001).

In Germany the government actively buys important specimens from private collectors (Rupert Wild, personal communication). The production of fossils from the Messel Lagerstätten was increased more than a thousand-fold by the work and ingenuity of commercial and private collectors. Most of the specimens that have been saved from these Eocene lake deposits are the result of a preparation transfer of the fossil to a resin matrix, a technique first pioneered by commercial collectors (Thomas Perner and Jurgen Henzel, personal communication). This new method permitted the recovery of articulated vertebrate remains with skin, feathers and stomach contents (Schaal and Ziegler 1992). One commercially collected specimen, a complete primate described and named Darwinius masillae, was suggested to be a pivotal “link” in the phylogenetic tree of our own species (Tudge 2009).

The Solnhofen area is one of the most important fossil sites in Germany and is still collected almost exclusively by people who sell the fossils they collect. This site has been operated commercially since the advent of the lithographic printing process in 1798 (Barthel et al. 1990). The Solnhofen Limestone has produced some of the most important fossils in the study of evolution, including the iconic early bird Archaeopteryx (Bergmann et al 2010). Every single specimen of Archaeopteryx known to science has been bought and sold (Ostrom 1985, Barthel et al. 1990).

Interestingly, the specimen of Archaeopteryx that is today one of the most accessible to the scientific community and the public is the Thermopolis specimen, in the private Wyoming Dinosaur Center, in Thermopolis (Wyoming, USA). This specimen has been displayed in Canada, China, Europe, Japan, and the US. It has been molded, photographed, Micro-CT scanned, laser-scanned and XRF scanned, and has generated multiple high-impact publications (Mayer et al. 2005, Bergmann et al. 2010). Despite this excellent academic work, some paleontologists have raised concerns on the ethics of publishing such material. For example, an academic paleontologist interviewed by the Los Angeles Times on 19 March 2006, stated “Ethically, in our profession, if a specimen is not in the public domain, its scientific worth is about zero.”

One particular site that has shed vital clues on the evolution of birds from dinosaurs was discovered in the 1990’s near Liaoning, China. Here farmers, turned commercial fossil collectors, have been excavating Lower Cretaceous lake deposits since the 1930’s. Then as today, these collectors sell their discoveries to scientists and the public alike. Virtually every fossil of scientific importance from these deposits has been bought and sold. These include thousands of fossil birds, some with exquisitely preserved plumage whose chemistry has been resolved and the pigmentation of feathers constrained (Wogelius et al. 2011). Perhaps the greatest scientific advancement derived from these commercially collected fossils is the irrefutable evidence that theropods had feathers and indeed extant birds are derived theropods (Currie and Chen 2001, Norell and Xu 2005. and Xu et al. 2010, etc.).

Morocco has, perhaps, the largest per-capita population of commercial fossil collectors of any country, with an estimated 50,000 collectors and annual fossil sales totaling $40,000,000.00 (Sicree 2009). These collectors and their activities are protected by law and the Ministere de l’Energie des Mines. Fossils are legally exported, but foreigners may not collect fossils unless it benefits the local commercial collectors (Sicree 2009, Bardet et al. 2010, Frommers 2014). Thus publications of Moroccan fossils must include discussions of fossils that were purchased (Bardet et al. 2010, Murray and Wilson 2014). In the open pit mines, huge machines excavate the Maestrichtian and Palaeogene aged phosphate deposits. Commercial collectors extract any fossils exposed by the latest pass of the machines and are responsible for most of what we know about this rich, but otherwise inaccessible fauna (Bardet et al. 2010, Bardet et al. 2013).

In the United States, the buying and selling of fossils has always been a part of paleontology. Marsh and Cope competed to purchase the latest discovery, whether it was a single bone, or a train car full of them, there was a desire to beat the other scientist to publication (Jaffe 2000). At the end of the 19th century, the Sternberg family began hunting fossils in the western United States and selling them throughout the world. Beginning with Charles H. and ending with George, the Sternbergs collected and sold anything from titanotheres to dinosaur mummies (Manning 2008). The dynasty even had one of its members, Charles M. Sternberg, accepted into the academic community (Rogers 1999).

If not for commercial fossil collecting in the lacustrine Green River Formation, little would be known beyond the five most common fish. It is only because of commercial quarries, that we have a more complete picture of the life in and around “Fossil Lake.” Without 100-plus commercial collectors over the last 100 years splitting limestone to collect fish after fish, science would never have seen the articulated mammals, lizards, snakes, and rarer fish, nor the feathered birds and all the plants and invertebrates that these diggers have produced (Grande 1984, Grande 2013).

Today, in the United States, commercial fossil collectors are barred from collecting fossils on Federal Land, but the rights of private landowners and the private ownership of fossils is maintained (The Paleontological Resources Preservation Act of 2009). Commercial collectors work legally on private land, and the landowners benefit financially from this activity, and thus are interested in the fossils on their land. The best of these collectors also work hand in hand with academics at both universities and museums. They employ scientists to help with data retrieval, restoration, mounting and finding the appropriate researchers to contact (Black Hills Institute, Siber & Siber, Triebold Paleontology, etc.).

New and important dinosaur specimens from the Morrison Formation (McIntosh et al. 1996, Redelstorff and Sander 2009, etc.), the Two Medicine Formation (Burnham et al. 2000, Evans and Larson 2003, etc.), and the Judith River Formation (Stein and Triebold 2013, Ott and Larson in press, etc.) have been recently discovered by commercial paleontologists and placed in museums, following the codes of ethics of the Association of Applied Paleontological Sciences, the Paleontological Society and the Society of Vertebrate Paleontology.

Some of the greatest contributions by commercial collectors have come from the Terminal Cretaceous Lance and Hell Creek Formations. These rocks have been reluctant to yield complete specimens because of a slow depositional environment and fragile, friable fossils that are difficult to collect. Commercial collectors applied their innovative techniques to the problem and discovered and collected vertebrates that would have otherwise never been seen by academic paleontologists, or the public. The most significant of these discoveries have ended up in museums. These include some of the most complete skeletons of Tyrannosaurus rex (Larson and Donnan 2002, Brochu 2003, N. Larson 2008, P. Larson 2008), Edmontosaurus (Christians 1992), Triceratops (The Childrens Museum in Indianapolis; Houston Museum of Natural Science; National Science Museum, Tokyo), a new Ceratopsian (Ott and Larson 2010) and a brand new oviraptorosaurian theropod (Lamanna et al. 2014).

This is by no means a comprehensive list of recent contributions by commercial collectors to the science of vertebrate paleontology, but it should provide a sense of the scope and scale of those significant contributions. Shimada et al. (2014), in contrast, suggest that recent developments in commercial collecting are actually damaging to the science and cite three examples. These examples are worthy of additional discussion and we thank Shimada et al. (2014) for raising these particular cases.

The first case is that of a skeleton of Tarbosaurus that was illegally collected, smuggled out of Mongolia and appeared at an auction in 2012. This is indeed a clear example of illegal activity that was thwarted by paleontologists working with law enforcement agencies. Commercial collectors applauded these actions because any illegal specimens that appear on the market unfairly compete with legal fossils. No fossil enthusiast approves of the destruction of sites or the theft and damage of specimens by those who work outside the law.

The second example was a 2013 bill (“HB 392”) that proposed allowing sales of fossils from Makoshika State Park in Glendive, Montana. This bill was passed by the Montana House for consideration by the State Senate. Although this might have been a naive move by a state representative or a park official, there is simply no evidence that the bill was the brainchild of commercial fossil collectors. In this case, the bill never made it out of the Senate.

The third and final case that Shimada et al. (2014) raise relates to the San Diego Museum of Natural History contracting with Bonhams to auction specimens originally purchased from C.H. Sternberg. Although the specimens had historical significance, they were of well-known and often duplicated taxa. “The Museum intended to use the money generated by the sale to purchase an important local fossil collection” (www.sdnhm.org/blog_details/fossils-withdrawn-from-auction/9/). Because of the public outcry from academic paleontologists (Perlman 2013) the specimens were withdrawn from the auction.

Shimada et al. (2014) stated: “We therefore consider the battle against heightened commercialization of fossils to be the greatest challenge to paleontology of the 21st century.” We believe, on the other hand, that the demonization and marginalization of a specific portion of the paleontological community is the result of misunderstanding, misplaced entitlement and simple intolerance. Such attitudes endanger the future of the very science of paleontology and paleontological collections on which it is based. Through collaboration, education and constructive alliances, the fossil fuel that drives our discipline could be better managed and made more easily accessible to the scientists who work in both commercial and/or academic institutions, but more importantly, made equally accessible to the public.

A recent Gallup poll (gallup.com/poll/21814/evolution-creationism-intelligent-design.aspx) shows that 46% of Americans believe that God created humans in their present form. The same poll revealed that 66% of Americans believe that the Earth is less than 10,000 years old. Fifty-four percent believe that creationism should be taught in schools. The challenges that our discipline faces are grave and we need a united front so that we might work together to make fossils more available to the general public, in museums and private collections, so that more people can touch, learn and understand the beautiful story that is the evolutionary history of life on Earth.

We must not forget that many of today’s public museums started out as private collections (Carnall 2013). Instead of castigating private collectors for their scientific curiosity and desire to collect, purchase or sell fossils, scientists would do far better by welcoming them into the fold. This would go a long way in helping to solve two real problems recognized by Shimada et al. (2014): a shrinking job market and diminishing funding sources.

Private collections also have a legitimate role in the preservation and study of our planetary heritage. Most private collectors gladly open their doors to any interested scientist and many readily donate specimens or money to research programs. The historical value of well-curated collections often end as bequests to museums. It is fair to say that this does necessitate patience on behalf of paleontologists wishing to house such collections, but this is the perfect reason to work with collectors to ensure a partnership that will help in the curation, conservation and preparation of samples and ultimately in its accession to a collection. To castigate such dedicated passion for our past can only be detrimental to the future of the science.

Although Shimada et al. (2014) are not alone in their beliefs, most paleontologists do not share their views; “[W]orking with private and amateur collectors can very realistically improve our knowledge about the natural world” (Carnall 2013). The Paleontological Society’s code of ethics states: “The principal importance of fossils is for scientific, scholarly, and educational use of both professionals and amateurs” (www.paleosoc.org/pscode.htm). They further state: “To leave fossils uncollected assures their degradation and ultimate loss to the scientific and educational world through natural processes of weathering and erosion.” In the National Academy of Sciences report on Paleontological Collecting (Raup et al. 1986), the committee not only recognize the contributions to paleontology by commercial and amateur collectors as are their rights on private lands, but also recommended that regulated amateur and commercial collecting be allowed on public lands.

People collect fossils because of scientific curiosity. They come from all walks of life. A very lucky few are able to find work as paleontologists in universities or museums. Others create companies that collect, buy and sell fossils. Some satiate their passion as volunteers or by maintaining fossil collections that are often eventually donated to their local museum. Working in partnership we can all help to solve the contracting job market and diminishing public funds for paleontological research and exhibits. However, if we remain divided…we may not fall, but simply fail the science at a time when we should be celebrating advances in the remarkable techniques and technology available to us in the 21st Century.

It is our humble opinion that the real “Greatest Challenge to Paleontology of the 21st Century”, is finding a way for amateurs, commercial fossil dealers and academic paleontologists to work together and do what is best for the public and the fossils. It’s the only way the science will thrive.

ACKNOWLEDGEMENTS

Thanks to P. J. Currie and P. L. Manning for reviewing this paper.

Whale fossil, 17 million years old, provides first exact date for East Africa’s puzzling uplift

Uplift associated with the Great Rift Valley of East Africa and the environmental changes it produced have puzzled scientists for decades because the timing and starting elevation have been poorly constrained.

Now paleontologists have tapped a fossil from the most precisely dated beaked whale in the world — and the only stranded whale ever found so far inland on the African continent — to pinpoint for the first time a date when East Africa’s mysterious elevation began.
The 17 million-year-old fossil is from the beaked Ziphiidae whale family. It was discovered 740 kilometers inland at an elevation of 620 meters in modern Kenya’s harsh desert region, said vertebrate paleontologist Louis L. Jacobs, Southern Methodist University, Dallas.
At the time the whale was alive, it would have been swimming far inland up a river with a low gradient ranging from 24 to 37 meters over more than 600 to 900 kilometers, said Jacobs, a co-author of the study.
The study, published in the Proceedings of the National Academy of Sciences, provides the first constraint on the start of uplift of East African terrain from near sea level.
“The whale was stranded up river at a time when east Africa was at sea level and was covered with forest and jungle,” Jacobs said. “As that part of the continent rose up, that caused the climate to become drier and drier. So over millions of years, forest gave way to grasslands. Primates evolved to adapt to grasslands and dry country. And that’s when — in human evolution — the primates started to walk upright.”
Identified as a Turkana ziphiid, the whale would have lived in the open ocean, like its modern beaked cousins. Ziphiids, still one of the ocean’s top predators, are the deepest diving air-breathing mammals alive, plunging to nearly 10,000 feet to feed, primarily on squid.
In contrast to most whale fossils, which have been discovered in marine rocks, Kenya’s beached whale was found in river deposits, known as fluvial sediments, said Jacobs, a professor in the Roy M. Huffington Department of Earth Sciences of SMU’s Dedman College of Humanities and Sciences. The ancient large Anza River flowed in a southeastward direction to the Indian Ocean. The whale, probably disoriented, swam into the river and could not change its course, continuing well inland.
“You don’t usually find whales so far inland,” Jacobs said. “Many of the known beaked whale fossils are dredged by fishermen from the bottom of the sea.”
Determining ancient land elevation is very difficult, but the whale provides one near sea level.
“It’s rare to get a paleo-elevation,” Jacobs said, noting only one other in East Africa, determined from a lava flow.
Beaked whale fossil surfaced after going missing for more than 30 years
The beaked whale fossil was discovered in 1964 by J.G. Mead in what is now the Turkana region of northwest Kenya.
Mead, an undergraduate student at Yale University at the time, made a career at the Smithsonian Institution, from which he recently retired. Over the years, the Kenya whale fossil went missing in storage. Jacobs, who was at one time head of the Division of Paleontology for the National Museums of Kenya, spent 30 years trying to locate the fossil. His effort paid off in 2011, when he rediscovered it at Harvard University and returned it to the National Museums of Kenya.
The fossil is only a small portion of the whale, which Mead originally estimated was 7 meters long during its life. Mead unearthed the beak portion of the skull, 2.6 feet long and 1.8 feet wide, specifically the maxillae and premaxillae, the bones that form the upper jaw and palate.
The researchers reported their findings in “A 17 million-year-old whale constrains onset of uplift and climate change in East Africa” online at the PNAS web site.
Modern cases of stranded whales have been recorded in the Thames River in London, swimming up a gradient of 2 meters over 70 kilometers; the Columbia River in Washington state, a gradient of 6 meters over 161 kilometers; the Sacramento River in California, a gradient of 4 meters over 133 kilometers; and the Amazon River in Brazil, a gradient of 1 meter over 1,000 kilometers.

Plants survive better through mass extinctions than animals

At least 5 mass extinction events have profoundly changed the history of life on Earth. But a new study led by researchers at the University of Gothenburg shows that plants have been very resilient to those events.

For over 400 million years, plants have played an essential role in almost all terrestrial environments and covered most of the world’s surface. During this long history, many smaller and a few major periods of extinction severely affected Earth’s ecosystems and its biodiversity.
In the upcoming issue of the journal New Phytologist, the team reports their results based on more than 20,000 plant fossils with the aim to understand the effects of such dramatic events on plant diversity. Their findings show that mass extinction events had very different impacts among plant groups. Negative rates of diversification in plants (meaning that more species died out than new species were formed) were never sustained through long time periods. This indicates that, in general, plants have been particularly good at surviving and recovering through tough periods.
“In the plant kingdom, mass extinction events can be seen as opportunities for turnover leading to renewed biodiversity,” says leading author Daniele Silvestro.
Most striking were the results for the Cretaceous-Paleogene mass extinction, caused by the impact of an asteroid off the Mexican coast some 66 million years ago. This event had a great impact on the configuration of terrestrial habitats and led to the extinction of all dinosaurs except birds, but surprisingly it had only limited effects on plant diversity.
Some important plant groups, such as the gymnosperms (including pines, spruce and firs) lost a great deal of their diversity through extinction. On the other hand, flowering plants (angiosperms) did not suffer from increased extinction, and shortly after the impact they underwent a new rapid increase in their diversity. These evolutionary dynamics contributed to make flowering plants dominate today’s global diversity above all other plant groups.
“Mass extinctions are often thought as a bad thing, but they have been crucial in changing the world into how we know it today,” says senior author Alexandre Antonelli.
If that asteroid had not struck the Earth, chances are that large dinosaurs would still be hunting around, mammals would be small and hiding in caves, and humans might never have evolved.
“By studying such extreme events we are trying to learn which groups of organisms and features are more sensitive to changes, so that we can apply this knowledge to protect biodiversity in the face of on-going climate change and human deterioration of natural ecosystems,” concludes Antonelli.

Swimming reptiles make their mark in the Early Triassic

Vertebrate tracks provide valuable information about animal behavior and environments. Swim tracks are a unique type of vertebrate track because they are produced underwater by buoyant trackmakers, and specific factors are required for their production and subsequent preservation. Early Triassic deposits contain the highest number of fossil swim track occurrences worldwide compared to other epochs, and this number becomes even greater when epoch duration and rock outcrop area are taken into account.

This spike in swim track occurrences suggests that during the Early Triassic, factors promoting swim track production and preservation were more common than at any other time. Coincidentally, the Early Triassic period follows the largest mass extinction event in Earth’s history, and the fossil record indicates that a prolonged period of delayed recovery persisted throughout this time period.
During this recovery interval, sediment mixing by animals living within the substrate was minimal, especially in particularly stressful environments such as marine deltas. The general lack of sediment mixing during the Early Triassic was the most important contributing factor to the widespread production of firm-ground substrates ideal for recording and preserving subaqueous trace fossils like swim tracks.