JCM NATURAL HISTORY LOG

Findings based on analysis of largest set of genetic markers ever studied
By Stuart Wolpert March 17, 2010

Dog breeds and wolves
Evolutionary tree of dog breeds and gray wolves

Dogs likely originated in the Middle East, not Asia or Europe, according to a new genetic analysis by an international team of scientists led by UCLA biologists. The research, funded by the National Science Foundation and the Searle Scholars Program, appears March 17 in the advance online edition of the journal Nature.

“Dogs seem to share more genetic similarity with Middle Eastern gray wolves than with any other wolf population worldwide,” said Robert Wayne, UCLA professor of ecology and evolutionary biology and senior author of the Nature paper. “Genome-wide analysis now directly suggests a Middle East origin for modern dogs. We have found that a dominant proportion of modern dogs’ ancestry derives from Middle Eastern wolves, and this finding is consistent with the hypothesis that dogs originated in the Middle East.

“This is the same area where domestic cats and many of our livestock originated and where agriculture first developed,” Wayne noted.

Previous genetic research suggested an East Asian origin for dogs, “which was unexpected,” Wayne said, “because there was never a hint in the archaeological record that dogs evolved there.”

“We were able to study a broader sampling of wolves globally than has ever been done before, including Middle Eastern wolves,” said the paper’s lead author, Bridgett vonHoldt, a UCLA graduate student of ecology and evolutionary biology in Wayne’s laboratory who studies the genetics of dog domestication. “In our analysis of the entire genome, we found that dogs share more unique markers with Middle Eastern wolves than with East Asian wolves. We used a genome-wide approach, which avoids the bias of single genome region.”

The biologists report genetic data from more than 900 dogs from 85 breeds (including all the major ones) and more than 200 wild gray wolves (the ancestor of domestic dogs) worldwide, including populations from North America, Europe, the Middle East and East Asia. They used molecular genetic techniques to analyze more than 48,000 genetic markers. No previous study has ever analyzed anywhere near that many markers.

The biologists have samples from Israel, Saudi Arabia and Iran — but they have not pinpointed a specific location in the Middle East where dogs originated.

“This study is unique in using a particular technology called a single nucleotide polymorphism, or SNP, genotyping chip; these chips interrogate the nucleotides at 48,000 locations in the genome,” said John Novembre, UCLA assistant professor of ecology and evolutionary biology and a member of UCLA’s Interdepartmental Program in Bioinformatics. “We are able to compare dogs looking at not just one small part of the genome, but at 48,000 different locations. That gives us the fine-scale resolution to analyze how these breeds are related to one another and how they are related to wolves.”

Previous genetic research had suggested an East Asian origin based on the higher diversity of mitochondrial sequences in East Asia and China than anywhere else in the world. (Mitochondria are tiny cellular structures outside the nucleus that produce energy and have their own small genome.) However, that research was based on only one sequence, a small part of the mitochondrial genome, Wayne noted.

“That research made extrapolations about how the domestic dog has evolved from examination of one region in the mitochondrial genome,” Wayne said. “This new Nature paper is a much more comprehensive analysis because we have analyzed 48,000 markers distributed throughout the nuclear genome to try to conclude where the most likely ancestral population is.

“What we found is much more consistent with the archaeological record,” he said. “We found strong kinship to Middle Eastern gray wolves and, to some extent, European gray wolves — but much less so to any wolves from East Asia. Our findings strongly contradict the conclusions based on earlier mitochondrial DNA sequence data.”

Eighty percent of dog breeds are modern breeds that evolved in the last few hundred years, Wayne said. But some dog breeds have ancient histories that go back thousands of years.

“We sampled both groups, the modern explosion of dog breeds and some of the ancient lineages,” he said. “Our data were aimed at resolving questions about the origin of domestic dogs, the evolution of dog breeds, and the history of dog breeds and relationships to their closest wild progenitor, the gray wolf.”

The first dogs that appeared in the Middle Eastern archaeological record date back some 12,000 to 13,000 years, Wayne said. Wolves have been in the Old World for hundreds of thousands of years. The oldest dogs from the archaeological record come from Europe and Western Russia.  A dog from Belgium dates back 31,000 years, and a group of dogs from Western Russia is approximately 15,000 years old, Wayne said.

“We know that dogs from the Middle East were closely associated with humans because they were found in ancient human burial sites,” Wayne said. “In one case, a puppy is curled up in the arms of a buried human.”

Some very old strains of dogs, with a history dating back more than several thousand years, may be mixed with modern breeds, enhancing their diversity in certain areas such as East Asia, Wayne said, interpreting the higher mitochondrial DNA diversity in that area of the globe.

There is one small set of East Asian breeds that does not indicate a strong Middle East origin, showing instead a high level of genetic sharing with Chinese wolves. This finding suggests there was some intermixing between East Asian dog breeds and East Asian wolves; the data do not make clear how long ago this occurred.

“However, the vast majority of dogs that we studied show significant levels of sharing with Middle Eastern wolves,” said Novembre, a population geneticist who studies genetic diversity and the lessons that can be learned from it.

Co-authors on the Nature paper include a group of researchers from the National Institutes of Health/National Human Genome Research Institute led by Elaine Ostrander; a group led by Carlos Bustamante, formerly of the Cornell University Department of Biological Statistics and Computational Biology and now a professor of genetics at the Stanford University School of Medicine; and scientists from China, Israel, Australia, Europe and Canada.

UCLA co-authors include Eunjung Han, a UCLA graduate student of Novembre’s in biostatistics; John Pollinger, director of UCLA’s Conservation Genetics Resource Center and associate director of the Center for Tropical Research at UCLA’s Institute of the Environment; and James Knowles, a graduate student from Canada’s University of Alberta working in Wayne’s laboratory. Wayne and Novembre’s research is federally funded by the National Science Foundation (www.nsf.gov). Novembre’s research is also funded by the Searle Scholars Program (www.searlescholars.net).

“By analyzing a sea of scientific data, Bob Wayne and John Novembre are at the forefront of the ‘new life sciences’ — which represents new ways to make discovery,” said Victoria Sork, dean of the UCLA Division of Life Sciences. “Their integration of genomic data with bioinformatic approaches illustrates how integration has enhanced our ability to analyze biological systems. Integration of knowledge is changing how we think about how life works. We are no longer limited to studying just one piece of a puzzle.”

Toy dogs and an evolutionary framework for dog domestication

The biologists have also found that when one looks at a relationship tree of modern and ancient dog breeds, there is surprising structure to it, and the structure mimics the classifications of dogs by breeders into herding dogs, retrievers, sight hounds, small terriers and others.

“We found there is a surprising genetic structure that accords with functional classifications — suggesting that new breeds are developed from crosses within specific breed groups that share particular traits,” Wayne said. “If they want a new sight hound, they tend to cross sight hounds with each other, and the same with herding dogs and retrieving dogs. That may not seem so surprising, but we had no reason to think beforehand that these groups would be strongly genealogical.

“There are some notable exceptions, such as ‘toy dogs.’ In this grouping, there are many different kinds of lineages represented, including traces of herding dogs and retrievers. When it comes to miniaturizing a dog, breeders start with a larger breed and cross that with a miniature dog to make a dwarfed breed on a new genetic background, causing the mixing of various lineages. It’s a mix-and-match approach for some of these breed groupings. But in other cases, new breeds have been based on combinations of breeds that have specific traits.”

New insights into the evolution of dogs have emerged from this Nature paper and several other recent studies by biologists, including Wayne and his colleagues.

“A framework about dog evolution is emerging,” Wayne said. “Even though dogs have an almost infinite variety of forms, geneticists have been discovering that much of this diversity has a simple genetic basis. Short-legged dogs — there are at least 19 such breeds, including dachshunds, corgis and basset hounds — have short legs due to the appearance of just one unique gene, a mutant growth-factor gene.”

Recent research by Wayne and his colleagues has identified genes responsible for short legs, small size, different fur types and different coat patterns and colors.

“It seems that in dogs, unlike other domesticated species, many of these different phenotypes distill to just a handful of genes,” Wayne said. “These genes have been mixed with retrievers, herding dogs and sight hounds to create new breeds.”

In humans, by contrast, most differences in height and weight involve many genes, each of which has only a small effect; most of the genes account for only about 1 or 2 percent of variability. Even in agricultural plants, most genes have only a small influence on a single trait.

In dogs, however, one gene that is responsible for differences in size accounts for more than 50 percent of the variation in body size, Wayne said. A small number of genes, he said, have been moved around in dogs to create the appearance of amazing diversity.

“Because we analyzed 48,000 locations in the genome, we can ask which regions are the most different between dogs and wolves,” said Novembre, whose research group investigated whether specific regions of the genome have changed under domestication. “We identified a few regions that are exceptionally different between dogs and wolves; these might be places in the genome where some of the changes occurred that make dogs and wolves different from each other today. These are good candidate regions for follow-up research.”

In a separate paper, Melissa Gray, who earned her Ph.D. from UCLA in Wayne’s laboratory, reported in February, along with Wayne and colleagues, on an important gene known as IGF1, which is responsible for small size in dogs, and analyzed which wolf populations are closest evolutionarily to this gene. The findings, published in the journal BMC Biology show that the gene appears to have arisen in Middle Eastern wolves, giving further support to the major claim in the new Nature paper.

The genes that are most beneficial to males are the most disadvantageous for females, and vice versa. However, this genetic conflict between the sexes is important in maintaining genetic variation within a species, researchers at Uppsala University have shown in a study on fruit-flies published in the open access journal PLoS Biology.

Males and females of many species often look quite different from one another. These differences are thought to have evolved because the sexes often have needs and strategies that do not coincide. For example, in fruit-flies, females may do best by concentrating their efforts in acquiring resources to lay more eggs, while males benefit by increasing their mating and fertilization success.

Such differences generate a sexual “conflict of interests,” and since as a general rule each characteristic of an organism is regulated by the same set of genes in the two sexes, this conflict takes place at the genetic level. Using a combination of behavioral studies and genomic technology, researchers Paolo Innocenti and Ted Morrow have succeeded in getting a first insight into which genes are influenced by this type of sexual conflict.

“Our study shows that genes whose expression is beneficial to males are also detrimental to females, and vice versa,” says Ted Morrow who led the study.

Their work also shows where in the genome these sexual conflict genes are, and that they are abundant in the sex-determining X-chromosome, something previously predicted by theory. These results indicate that a genotype that is optimal for both sexes does not exist.

The full article can be found at: http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pbio.1000335

A synopsis can be found at:  http://www.plos.org/press/plbi-08-03-InnocentiSynopsis.pdf

A genetic study has found that small domestic dogs probably originated in the Middle East more than 12,000 years ago. Researchers writing in the open access journal BMC Biology traced the evolutionary history of the IGF1 gene, finding that the version of the gene that is a major determinant of small size probably originated as a result of the domestication of the Middle Eastern gray wolf.

Melissa Gray and Robert Wayne, from the University of California, Los Angeles, led a team of researchers who surveyed a large sample of gray wolf populations. She said, “The mutation for small body size post-dates the domestication of dogs. However, because all small dogs possess this variant of IGF1, it probably arose early in their history. Our results show that the version of the IGF1 gene found in small dogs is closely related to that found in Middle Eastern wolves and is consistent with an ancient origin in this region of small domestic dogs.”

Previous archeological work in the Middle East has unearthed the remains of small domestic dogs dating to 12,000 years ago. Sites in Belgium, Germany and Western Russia contain older remains (13,000-31,000 years ago), but these are of larger dogs. These findings support the hypothesis put forward by Gray and colleagues that small body size evolved in the Middle East.

Reduction in body size is a common feature of domestication and has been seen in other domesticated animals including cattle, pigs and goats. According to Gray, “Small size could have been more desirable in more densely packed agricultural societies, in which dogs may have lived partly indoors or in confined outdoor spaces.”

The article discussed is:  Gray MM, Sutter NB, Ostrander EA, Wayne RK: IGF1 Haplotyping supports a Middle
Eastern Origin for small dogs.  BMC Biology 2010, 8:16.

A trio of biologists, including two from East Carolina University, have discovered in Peru the first confirmed species of monogamous amphibian, Ranitomeya imitator, better known as the mimic poison frog — a finding that provides groundbreaking insight into the ecological factors that influence mating behavior.

To the left:  A family group of Ranitomeya imitator amphibians, better known as mimic poison frogs. Credit: Photo courtesy of Jason Brown.
The scientists’ work, which is to be published in the April issue of The American Naturalist, may be the most solid evidence yet that monogamy can have a single ecological cause.

“We were able to tie the evolution of monogamy and the evolution of biparental care to variation in a single ecological factor, and that’s rare,” said Kyle Summers, an ECU biology professor whose specialties include evolutionary ecology and evolutionary genetics. Summers authored the study with Jason L. Brown, a former ECU graduate student now a researcher at Duke University, and Victor Morales of Ricardo Palma University in Lima, Peru.

Analyzing data on 404 frog species, the biologists found a strong association between the use of small pools for breeding, and the evolution of parental care, including intensive parental care involving egg-feeding and the participation of both parents. The researchers then focused in on the mating and parenting habits of two similar frog species, the mimic poison frog and the R. variabilis, more commonly known as the variable poison frog, that differed mainly in the size of the breeding-pool.

They theorized that the differences in parental care and mating system between these otherwise similar species stemmed from the relative availability of resources in the breeding pools. The tadpole of the mimic poison frog grows up in much smaller, less nutrient-dense water pools that form in the folds of tree leaves. They are ferried there after hatching by males, who monitor them in the months following birth. About once a week, the male calls for his female partner, who lays non-fertile eggs for the tadpoles to eat.

The variable poison frog, however, raises its tadpoles in larger pools. Here, as with most amphibians, rearing of the young is handled mostly by the male.

To test their theory, scientists moved tadpoles from both species into differently sized pools. Tadpoles in larger pools thrived while tadpoles in smaller pools did not grow.

This, the scientists said, means that tadpoles living in the larger, more nutrient-rich pools don’t need the work of two parents as much as their smaller-pond counterparts. Species that raised tadpoles in smaller ponds were more likely to require the skills of both parents. In turn, this likely favored parents who remained devoted only to the offspring that they had produced together.

The researchers used genetic analysis based on techniques similar to the DNA-based forensic methods used for paternity cases to investigate the mating system of the mimic poison frog. Surprisingly, the all but one of the families investigated were completely genetically monogamous. Many animals thought to practice social monogamy have been found through genetic testing to be less faithful than previously believed. Monogamy “turns out to be relatively rare, eve in birds and mammals — particularly in mammals — and reptiles,” Summers said. “Finding a frog that has a monogamous mating system was pretty novel for us.”

The biologists’ work already has attracted attention from scientific and popular media, both international and national. While the idea that ecological factors — say, scarcity of resources — have contributed to monogamous behavior in humans and other animals is well accepted, Summers cautioned against drawing inferences about human behavior from the findings.

“People are interested in whether there are parallels between mating systems of other species and our own,” he said. “Of course, the human situation is so different from other species. It’s somewhat perilous to over interpret the similarities. You can’t just translate it.”

Citation: Brown, J. et al. 2010. A Key Ecological Trait Drove the Evolution of Biparental Care and Monogamy in an Amphibian. The American Naturalist 175: 436–446.

A puzzle that has baffled scientists for centuries — why some birds appear to be male on one side of the body and female on the other — has been solved by researchers.

The research, which involved studying rare naturally occurring chickens with white (male) plumage on one side and brown (female) plumage on the other, sheds new light on the sexual development of birds.

It was previously thought that sex chromosomes in birds control whether a testis or ovary forms, with sexual traits then being determined by hormones.

The researchers, however, identified differences between male and female cells that control the development of sexual traits. The scientists have named the phenomenon, cell autonomous sex identity (CASI).

The study from The Roslin Institute at the University of Edinburgh, which receives key funding from the Biotechnology and Biological Sciences Research Council, is published in the journal Nature.

The findings, which are scientifically revolutionary in the field, may also be relevant to why males and females differ in behaviour and in susceptibility to disease.

They could also lead to improvements in poultry production — identification of some of the molecular differences between male and female cells should lead to better tests for sexing embryos prior to hatch. It might even be possible to devise ways of obtaining the growth characteristics of male birds in females, with improvements in feed efficiency and productivity that could contribute to future food security.

Dr Michael Clinton, who led the study, said: “This research has completely overturned what we previously thought about how sexual characteristics were determined in birds. We now believe that the major factors determining sexual development are built into male and female cells and derive from basic differences in how sex chromosome genes are expressed. Our study opens a new avenue for our understanding of sexual development in birds.

“It also means we must now reassess how this developmental process occurs in other organisms. There is already some evidence that organs such as the heart and brain are intrinsically different in males and females and birds may provide a model for understanding the molecular basis for these gender differences.”

Citation: Zhao D. et al. 2010.Somatic sex identity is cell autonomous in the chicken. Nature 464, 237-242.

Two Dartmouth biologists have found that brown anole lizards make an interesting choice when deciding which males should father their offspring. The females of this species mate with several males, then produce more sons with sperm from large fathers, and more daughters with sperm from smaller fathers. The researchers believe that the lizards do this to ensure that the genes from large fathers are passed on to sons, who stand to benefit from inheriting the genes for large size.

The male of this species can be two to three times the mass of the female, but the females seem to be in control of the genetic destiny. (Credit: Photo by Joseph Mehling '69)

The study is published in the March 4 issue of Science Express, the advance online publication of the journal Science.

“This species has figured out a clever way to pass on genes with gender-specific effects on fitness,” said Bob Cox, the lead author on the paper and a post-doctoral researcher at Dartmouth. “Usually, when natural selection pulls genes in different directions for each gender, the species faces an evolutionary dilemma. But these lizards have solved this puzzle, they’ve figured out how to get the right genes into the right gender.”

By manipulating opportunities for females to mate with males of different sizes, the researchers determined that females prefer larger males. But, when the choice of partners was limited to small males, females minimized the production of sons.

The researchers explain that the genes that make males more fit are often different from the genes that benefit females, which presents a conundrum because males and females share most of their DNA. The valuable traits for one gender are not always the same for the other. “In an evolutionary sense, what’s good for the goose is not always good for the gander,” said Cox.

In these lizards, however, mothers can enhance the fitness of their offspring by manipulating their gender depending on the size of the father. To demonstrate this, Cox and Calsbeek measured the survival rates of sons and daughters over eight months when released to their natural habitat in The Bahamas.

“As we predicted, the survival of the male offspring increased if they had large fathers,” said Calsbeek. “But, we found that the survival of the daughters was not influenced by the size of the father. This suggests that the genetic benefits of large size are specific to sons.”

How do females control the gender of their progeny? “That’s the big question at this point,” said Cox. The researchers will continue their studies to learn more about the mechanisms involved in this most fundamental of all evolutionary processes, the struggle to pass on advantageous genetic material.

On Thursday 4th March 2010, Karachi, Dr Sheh Shah, President of the Pakistan Medical Association, Dr Habib-ur-Rehman Soomro, Secretary General PMA and Dr Huma Qureshi, Executive Director Pakistan Medical Research Council launched the world’s first comprehensive snakebite protocol called ‘A2 Snakebite Management in Asia and Africa’ for use by doctors to treat snakebite in the key areas of Africa and Asia.

Snakebite has been described as a ‘neglected disease’ and yet little practical work has been done by experts to attempt to reduce the suffering caused by snakebite. The need for better guidelines has been frequently discussed but action has been conspicuously lacking. Pakistan published a National Snakebite Protocol in 2008, based on a comprehensive analysis of the conditions and infrastructure present in front line hospitals that deal with snakebite.

Above: The Malyan Pitviper (Calloselasma rhodostoma) is responsible for may envenomations in Southeast Asia. Photo: John C. Murphy.

Dr Qureshi said, “Following the success of the local protocol we decided to set ourselves the challenge of assisting with comprehensive guidelines for our African and Asian neighbours in a bid to contribute a major reduction in mortality. The use of western medical textbooks has led to sub optimal anti snake venom (ASV) dosages, ASV being given to patients who are not envenomed and too much ASV being given due to the lack of clear clinical endpoints for ASV therapy and many other problems in treatment”.

Over 95% of the world’s mortality from snakebite originates in Africa and Asia and Pakistan is ideally situated in geographical terms and in terms of it’s position in the top five countries for mortality, to provide guidance on the most effective way to approach snakebite.

The guidelines contain excellent photographs of the major medically significant snakes in Africa and Asia and recommendations for the use and dosage of anti snake venom. In addition, it includes chapters on first aid, prevention and some of the key support areas such as dealing with neurotoxic species and adverse reactions to anti venom.  There is also a unique chapter on the practical aspects of managing airway in snakebite, which has great applicability across other medical conditions.

Dr Shah stated, “The PMA has a long and distinguished history of supporting and endorsing practical solutions to medical conditions that affect the rural poor. Developed world snakebite experts do not understand the priority of snakebite in developing countries or the nature of local conditions. Many recommendations such as the routine use of mechanical ventilators are just not possible in developing country set-ups”.

There are useful guidelines on how to equip a basic medical facility to treat snakebite and methods to treat and effectively refer patients from a basic facility to a better-equipped hospital, which is crucial if significant reductions in mortality are to be secured.

Ian Simpson, the author stated, “The guidelines are specifically targeted at rural doctors in Africa and Asia who are based at basic health facilities and contain chapters of specific interest to health officials and administrators. It is vital that health officials ensure the right drugs and simple equipment are available in the correct quantities and that they can determine if their doctors are treating snakebite using the most effective methods”.

In order for doctors to be able to freely download the guidelines locally, the guidelines are available online at:

http://www.pmrc.org.pk/index_2.htm

This enables doctors to print out those sections specific to their area.

Dr Qureshi said, “These guidelines will also help to more efficiently use currently produced anti snake venom and enable useful epidemiology data to be gathered with consistent and rational processes. Recent snakebite mortality assessments for Pakistan have been heavily overstated and effective protocols such as this will enable more accurate reporting”.

Giant plankton-eating fishes roamed the prehistoric seas for over 100 million years before they were wiped out in the same event that killed off the dinosaurs, new fossil evidence has shown.

An international team describe how new fossils from Asia, Europe and the US reveal a previously unknown dynasty of giant plankton-eating bony fishes that filled the seas of the Jurassic and Cretaceous periods, between 66-172 million years ago.
The team report their findings in this week’s Science.

Illustration of Bonnericthys by Robert Nicholls

‘Today’s giant plankton-feeders – such as baleen whales, basking sharks and manta rays – include the largest living vertebrate animals, so the fact that creatures of this kind were missing from the fossil record for hundreds of millions of years was always a mystery,’ said Dr Matt Friedman of Oxford University’s Department of Earth Sciences, an author of the report.

‘We used to think that the seas were free of big filter feeders during the age of dinosaurs, but our discoveries reveal that a dynasty of giant fishes filled this ecological role in the ancient oceans for more than 100 million years.’

Diagram showing reconstruction of Bonnericthys and position of bones Several of the most important new fossils came from deposits in Kansas in the USA, with other remains from as far afield as Dorset and Kent in the UK, and Japan. Some members of this filter-feeding fish group are estimated to have been up to 9 metres long, a similar size to modern plankton-eating giants such as the basking shark.

‘One of the reasons these big fishes were overlooked or misidentified lies in their anatomy,’ said Dr Friedman. ‘Over their evolutionary history, these fishes reduced the amount of bone in their skeletons, probably to save weight, with the consequence that most of their hard parts were easily scattered after death. As it turns out, the only parts you routinely find in the fossil record are their well-developed forefins.’

With few clues to go on, palaeontologists had argued that the owner of these isolated fins looked something like the modern-day swordfish. This changed when some of Dr Friedman’s colleagues began cleaning a fossil that preserved skull bones along with the fins.

Dr Friedman said: ‘Instead of finding a head with a long sword-like snout and jaws lined with predatory fangs, they found something completely different: long, toothless jaws supporting a gaping mouth, and long, rod-like bones that contributed to the huge gill arches needed to filter out enormous quantities of tiny plankton.’ The team named this fish Bonnerichthys, honouring the Kansas family who discovered the fossil.

Remains of similar giant plankton-eating fishes had been known from much older rocks, but they were thought to be a short-lived and unsuccessful evolutionary experiment. ‘As soon as we recognised that these animals had a longer history than anyone thought, I started examining museum collections and found more examples that had been overlooked or misidentified,’ explained Dr Friedman. Revisiting previously collected fossils netted the team evidence that these fishes thrived for millions of years and colonised many parts of the globe.

Intriguingly the ancestors of large modern filter-feeders such as baleen whales and whale sharks only appeared after the extinction of Bonnerichthys and its relatives, suggesting that today’s filter-feeders evolved to fill the ecological niche left behind by these plankton-eating contemporaries of the dinosaurs.

he research team consisted of scientists from Oxford University (UK), DePaul University, Chicago (US), Fort Hays State University, Kansas (US), University of Kansas (US), University of Glasgow (UK), and Triebold Paleontology Inc & Rocky Mountain Dinosaur Resource Centre, Colorado (US).

A report of the research, entitled ‘100-Million-Year Dynasty of Giant Planktivorous Bony Fishes in the Mesozoic Seas’, is published in this week’s Science.