Ancient Insects Shed Light On Biodiversity

Simon Fraser University evolutionary biologists Bruce Archibald and Rolf Mathewes, and Brandon University biologist David Greenwood, have discovered that modern tropical mountains’ diversity patterns extended up into Canada about 50 million years ago.
Their findings confirm an influential theory about change in modern species diversity across mountains, and provide evidence that global biodiversity was greater in ancient times than now. The scientific journal Palaeogeography, Palaeoclimatology, Palaeoecology has published their research.

About 45 years ago, an evolutionary biologist at the University of Pennsylvania theorized that change in species from site to site across mountain ranges in the tropics should be greater than in temperate latitudes.

Daniel Janzen reasoned that the great difference between summer and winter in temperate latitudes (high seasonality) offers a wide window to migrate across mountainous regions. The small difference in the tropics (low seasonality) allows a very narrow opportunity, annually. Consequently, communities across tropical mountains should have fewer of the same species. Many studies examining modern communities support this theory.

Archibald, Mathewes and Greenwood realized that fossil beds across a thousand kilometres of the ancient mountains of British Columbia and Washington provided a unique lens through which to deepen evaluation of this theory.

Fifty million years ago, when these fossil beds were laid down, the world had low seasonality outside of the tropics, right to the poles. Because of this, if Janzen’s theory is right, the pattern of biodiversity that he described in modern tropical mountains should have extended well into higher latitudes.

“We found that insect species changed greatly across British Columbia’s and Washington State’s ancient mountain ranges, like in the modern tropics,” Archibald says, “exactly as Janzen’s seasonality hypothesis predicted.

This implies that it’s the particular seasonality now found in the modern tropics, not where that climate is situated globally, that affects this biodiversity pattern.” He adds: “Sometimes it helps to look to the ancient past to better understand how things work today.”

The findings also bolster the idea that ancient Earth was a much more diverse world than now with many more species.

Giant Fossil Predator Provides Insights Into the Rise of Modern Marine Ecosystem Structures

Jan. 7, 2013 — An international team of scientists has described a fossil marine predator measuring 8.6 meters in length (about 28 feet) recovered from the Nevada desert in 2010 as representing the first top predator in marine food chains feeding on prey similar to its own size.

A paper with their description will appear the week of Jan. 7, 2013 in the early electronic issue of Proceedings of the National Academy of Sciences.

Scientists who studied the fossil include lead author Dr. Nadia Fröbisch and Prof. Jörg Fröbisch (both at Museum für Naturkunde Leibniz-Institut für Evolutions- und Biodiversitätsforschung), Prof. P. Martin Sander (Steinmann Institute of Geology, Mineralogy, and Paleontology, Division of Paleontology, University of Bonn), Prof. Lars Schmitz (W. M. Keck Science Department, Claremont McKenna, Pitzer, and Scripps Colleges, Claremont, California) and Dr. Olivier Rieppel (The Field Museum, Chicago, Illinois).

The 244-million-year-old fossil, named Thalattoarchon saurophagis (lizard-eating sovereign of the sea) is an early representative of the ichthyosaurs, a group of marine reptiles that lived at the same time as dinosaurs and roamed the oceans for 160 million years. It had a massive skull and jaws armed with large teeth with cutting edges used to seize and slice through other marine reptiles in the Triassic seas. Because it was a meta-predator, capable of feeding on animals with bodies similar in size to its own, Thalattoarchon was comparable to modern orca whales.

Remarkably, only eight million years prior to the appearance of Thalattoarchon, a severe extinction at the end of the Permian period killed as many as 80 to 96 percent of species in the Earth’s oceans. The rise of a predator such as Thalattoarchon documents the fast recovery and evolution of a modern ecosystem structure after the extinction.

“Everyday we learn more about the biodiversity of our planet including living and fossil species and their ecosystems” Dr. Fröbisch said. “The new find characterizes the establishment of a new and more advanced level of ecosystem structure. Findings like Thalattoarchon help us to understand the dynamics of our evolving planet and ultimately the impact humans have on today’s environment.”

“This discovery is a good example of how we study the past in order to illuminate the future,” said Dr. Rieppel of The Field Museum.

The ichthyosaur was recovered from what is today a remote mountain range in central Nevada. Most of the animal was preserved, including the skull (except the front of the snout), parts of the fins, and the complete vertebral column up to the tip of the tail. Supported by a grant from the National Geographic Society’s Committee for Research and Exploration, the team of paleontologists took three weeks to unearth the ichthyosaur and prepare it for its transport by helicopter and truck out of the field.

New Dinosaur: First Freshwater Mosasaur Discovered

Dec. 19, 2012 — A new mosasaur species discovered in Hungary is the first known example of this group of scaled reptiles to have lived in freshwater river environments similar to modern freshwater dolphins.
The research is published Dec. 19 in the open-access journal PLOS ONE by Laszlo Makadi from the Hungarian Natural History Museum, Hungary and colleagues from the University of Alberta, Canada and MTA-ELTE Lendület Dinosaur Research Group, Hungary.
The species lived about 84 million years ago, the largest specimens reached about 20 feet in length, and belongs to a family called ‘mosasaurs’, conventionally thought of as gigantic finned marine lizards, similar and perhaps even related to present day monitor lizards. The researchers discovered several fossils of the new species, ranging from small juveniles to large adults that suggest that this species had limbs like a terrestrial lizard, a flattened, crocodile-like skull, and a tail unlike other known members of the mosasaur family.
The fossils were recovered from an open-pit mine in the Bakony Hills of Western Hungary, which were once flood-plains. According to the study, this is the first known mosasaur that lived in freshwater, and only the second specimen of a mosasaur to have been found in rocks that were not once deposited in the ocean. Makadi says, “The evidence we provide here makes it clear that similar to some lineages of cetaceans, mosasaurs quickly adapted to a variety of aquatic environments, with some groups re- invading available niches in freshwater habitats. The size of Pannoniasaurus makes it the largest known predator in the waters of this paleo-environment.”
Even in the modern world, scaly reptiles in the aquatic world are extremely rare. Only a few species live in the water, and even fewer, like marine iguanas and sea kraits, live in the oceans. The new species described here probably adapted to freshwater environments similarly to river dolphins, such as those now inhabiting the Amazon, Ganges and Yangtze rivers.

Paleo-Ocean Chemistry: New Data Challenge Old Views About Evolution of Early Life

Dec. 23, 2012 — A research team led by biogeochemists at the University of California, Riverside has tested a popular hypothesis in paleo-ocean chemistry, and proved it false.
The fossil record indicates that eukaryotes — single-celled and multicellular organisms with more complex cellular structures compared to prokaryotes, such as bacteria — show limited morphological and functional diversity before 800-600 million years ago. Many researchers attribute the delayed diversification and proliferation of eukaryotes, which culminated in the appearance of complex animals about 600 million years ago, to very low levels of the trace metal zinc in seawater.
As it is for humans, zinc is essential for a wide range of basic cellular processes. Zinc-binding proteins, primarily located in the cell nucleus, are involved in the regulation of gene transcription.
Eukaryotes have increasingly incorporated zinc-binding structures during the last third of their evolutionary history and still employ both early- and late-evolving zinc-binding protein structures. Zinc is, therefore, of particular importance to eukaryotic organisms. And so it is not a stretch to blame the 1-2-billion-year delay in the diversification of eukaryotes on low bioavailability of this trace metal.
But after analyzing marine black shale samples from North America, Africa, Australia, Asia and Europe, ranging in age from 2.7 billion years to 580 million years old, the researchers found that the shales reflect high seawater zinc availability and that zinc concentrations during the Proterozoic (2.5 billion to 542 million years ago) were similar to modern concentrations. Zinc, the researchers posit, was never biolimiting.
Study results appear online Dec. 23 in Nature Geoscience.
“We argue that the concentration of zinc in ancient marine black shales is directly related to the concentrations of zinc in seawater and show that zinc is abundant in these rocks throughout Earth’s history,” said Clint Scott, the first author of the research paper and a former UC Riverside graduate student. “We found no evidence for zinc biolimitation in seawater.”
Scott, now a research geologist with the U.S. Geological Survey, explained that the connection between zinc limitation and the evolution of eukaryotes was based largely on the hypothesis that Proterozoic oceans were broadly sulfidic. Under broadly sulfidic conditions, zinc should have been scarce because it would have rapidly precipitated in the oceans, he explained.
“However, a 2011 research paper in Nature also published by our group at UCR demonstrated that Proterozoic oceans were more likely broadly ferruginous — that is, low in oxygen and iron-rich — and that sulfidic conditions were more restricted than previously thought,” said Scott, who performed the research in the lab of Timothy Lyons, a professor of biogeochemistry and the principal investigator of the research project.
The research team argues that ferruginous deep oceans, combined with large hydrothermal fluxes of zinc via volcanic activity on the seafloor, maintained high levels of dissolved zinc throughout the oceans and provided a relatively stable marine reservoir of the trace metal over the past 2.7 billion years.
“The key challenge in understanding the early evolution of life is recognizing the environmental conditions under which that life first appeared and diversified,” Lyons said. “We have taken a very direct approach that specifically tracks the availability of essential micronutrients, and, to our surprise, zinc supplies in ancient seawater were much higher and less variable than previously imagined.
“We can imagine for the first time,” he quipped, “that zinc supplements were not on the shopping lists of our early eukaryotic ancestors, and so we better find another reason to explain the mysterious delay in their rise in the ocean.”
Scott, who graduated with a doctoral degree in geological sciences from UCR in 2009, and Lyons were joined in the study by Noah J. Planavsky, a former UCR graduate student in Lyons’ lab; Chris L. Dupont at the J. Craig Venter Institute, La Jolla, Calif.; Brian Kendall and Ariel D. Anbar at Arizona State University; Benjamin C. Gill at Virginia Polytechnic Institute and State University and also a former member of the Lyons lab; Leslie J. Robbins and Kurt O. Konhauser at the University of Alberta, Canada; Kathryn F. Husband and Simon W. Poulton at the University of Leeds, United Kingdom; Gail L. Arnold at the Max Planck Institute for Marine Microbiology, Germany; Boswell A. Wing at McGill University, Canada; and Andrey Bekker at the University of Manitoba, Canada.
The idea for the study was a direct consequence of the 2011 Nature paper by Planavsky, Scott, Lyons and others that challenged the hypothesis of broadly sulfidic oceans.
The international collaboration received funding for the study from numerous sources. In the U.S., funding came from the National Science Foundation, the NASA Astrobiology Institute and the Agouron Institute.

Researchers Find First Evidence of Ice Age Wolves in Nevada

Dec. 13, 2012 — A University of Nevada, Las Vegas research team recently unearthed fossil remains from an extinct wolf species in a wash northwest of Las Vegas, revealing the first evidence that the Ice Age mammal once lived in Nevada.

The metapodial, or foot bone, was uncovered late last year by UNLV geologist Josh Bonde during a survey of the Upper Las Vegas Wash. They have now confirmed that the bone comes from a dire wolf.

The discovery site is near the proposed Tule Springs Fossil Beds National Monument, a fossil-rich area known for its diversity and abundance of Ice Age animal remains. Scientists estimate the fossil to be 10,000 to 15,000 years old during the Late Pleistocene period.

“Dire wolves are known to have lived in almost all of North America south of Canada, but their historical presence in Nevada has been absent until now,” said Bonde, a UNLV geology professor. He was a Ph.D. student at the university when he discovered the bone.

“The Tule Springs area has turned up many species, but it’s exciting to fill in another part of the map for this animal and reveal a bit more about the Ice Age ecosystem in Southern Nevada.”

The dire wolf, a larger relative of the gray wolf, was present in much of North and South America for more than a million years. Scientists theorize that competition from other wolf species and a possible food scarcity led to its extinction roughly 10,000 years ago.

Foot bones of the extinct dire wolf are difficult to distinguish from those of the gray wolf. Researchers conclude bone is likely from a dire wolf because of the abundance of dire wolf fossils―and scarcity of gray wolf fossils―in similar-aged excavation sites throughout the Southwest.

Fossil remains of dire wolves are abundant in the La Brea tar pits and have been found in other Southwestern states. Many of the same species of Ice Age animals found at La Brea have also been recovered in the Las Vegas Valley, including Columbian mammoths, camels, horses, bison, and ground sloths.

“This discovery helps flesh out Southern Nevada’s Pleistocene ecosystem and shows that there are still important discoveries to be made in the Upper Las Vegas Wash,” said UNLV geology professor Steve Rowland, a collaborator with Bonde on the study of local Ice Age fossils. “To understand why certain species became extinct and others did not, we need to learn as much as possible about predatory habits and which species were especially sensitive to changes in the environment.”

The announcement comes on the heels of a recent discovery in the same wash of a saber-tooth cat by researchers from the San Bernardino County Museum. Like dire wolves, saber-tooth cats were Pleistocene predators that had been conspicuously absent from the Southern Nevada fossil record.

According to Rowland, Tule Springs was a spring-fed, swampy area during periods of the Late Pleistocene, an ideal spot for plant-eating animals and their carnivorous predators.

The recent discoveries come exactly 50 years after scientists conducted a ‘big dig’ at Tule Springs, revealing the site to be rich with Ice Age fossils.

“Tule Springs likely had the highest density of large animals in the area during the Late Pleistocene, and the marshy environment was very good for preserving at least some of the bones and teeth of animals that died there,” said Rowland.

“In the 50 years since the ‘big dig,’ the scientists have confirmed that humans interacted with Ice Age animals. We now have a new list of questions about life and death in the Pleistocene, and a new tool kit of research techniques to help us get the answers.”

The identity of the find was confirmed by Xiaoming Wang of the Los Angeles County Museum of Natural History, an expert on extinct species of the dog family. Bonde has been surveying the Tule Springs area since 2007, and he and a group of UNLV undergraduate studentss are prospecting for more fossils.

The center of the original ‘big dig’ is on the same parcel of land where Bonde discovered the wolf fossil.

The dire wolf bone, in addition to other bones collected by UNLV researchers, are cataloged, studied, and stored at UNLV.

Asteroid That Killed the Dinosaurs Also Wiped out the ‘Obamadon’

Dec. 10, 2012 — The asteroid collision widely thought to have killed the dinosaurs also led to extreme devastation among snake and lizard species, according to new research — including the extinction of a newly identified lizard Yale and Harvard scientists have named Obamadon gracilis.

“The asteroid event is typically thought of as affecting the dinosaurs primarily,” said Nicholas R. Longrich, a postdoctoral associate with Yale’s Department of Geology and Geophysics and lead author of the study. “But it basically cut this broad swath across the entire ecosystem, taking out everything. Snakes and lizards were hit extremely hard.”

The study was scheduled for online publication the week of Dec. 10 in the Proceedings of the National Academy of Sciences.

Earlier studies have suggested that some snake and lizard species (as well as many mammals, birds, insects and plants) became extinct after the asteroid struck Earth 65.5 million years ago, on the edge of the Yucatan Peninsula. But the new research argues that the collision’s consequences were far more serious for snakes and lizards than previously understood. As many as 83 percent of all snake and lizard species died off, the researchers said — and the bigger the creature, the more likely it was to become extinct, with no species larger than one pound surviving.

The results are based on a detailed examination of previously collected snake and lizard fossils covering a territory in western North America stretching from New Mexico in the southwestern United States to Alberta, Canada. The authors examined 21 previously known species and also identified nine new lizards and snakes.

They found that a remarkable range of reptile species lived in the last days of the dinosaurs. Some were tiny lizards. One snake was the size of a boa constrictor, large enough to take the eggs and young of many dinosaur species. Iguana-like plant-eating lizards inhabited the southwest, while carnivorous lizards hunted through the swamps and flood plains of what is now Montana, some of them up to six feet long.

“Lizards and snakes rivaled the dinosaurs in terms of diversity, making it just as much an ‘Age of Lizards’ as an ‘Age of Dinosaurs,'” Longrich said.

The scientists then conducted a detailed analysis of the relationships of these reptiles, showing that many represented archaic lizard and snake families that disappeared at the end of the Cretaceous, following the asteroid strike.

One of the most diverse lizard branches wiped out was the Polyglyphanodontia. This broad category of lizards included up to 40 percent of all lizards then living in North America, according to the researchers. In reassessing previously collected fossils, they came across an unnamed species and called it Obamadon gracilis. In Latin, odon means “tooth” and gracilis means “slender.”

“It is a small polyglyphanodontian distinguished by tall, slender teeth with large central cusps separated from small accessory cusps by lingual grooves,” the researchers write of Obamadon, which is known primarily from the jaw bones of two specimens. Longrich said the creature likely measured less than one foot long and probably ate insects.

He said no one should impute any political significance to the decision to name the extinct lizard after the recently re-elected U.S. president: “We’re just having fun with taxonomy.”

The mass (but not total) extinction of snakes and lizards paved the way for the evolution and diversification of the survivors by eliminating competitors, the researchers said. There are about 9,000 species of lizard and snake alive today. “They didn’t win because they were better adapted, they basically won by default, because all their competitors were eliminated,” Longrich said.

Co-author Bhart-Anjan S. Bhullar, a doctoral student in organismic and evolutionary biology at Harvard University, said: “One of the most important innovations in this work is that we were able to precisely reconstruct the relationships of extinct reptiles from very fragmentary jaw material. This had tacitly been thought impossible for creatures other than mammals. Our study then becomes the pilot for a wave of inquiry using neglected fossils and underscores the importance of museums like the Yale Peabody as archives of primary data on evolution — data that yield richer insights with each new era of scientific investigation.”

Jacques A. Gauthier, professor of geology and geophysics at Yale and curator of vertebrate paleontology and vertebrate zoology, is also an author.

The paper is titled “Mass Extinction of Lizards and Snakes at the Cretaceous-Paleogene Boundary.” The National Science Foundation and the Yale Institute for Biospheric Studies supported the research.

America’s Ancient Hurricane Belt and the U.S.-Canada Equator

ScienceDaily (Nov. 15, 2012) — The recent storms that have battered settlements on the east coast of America may have been much more frequent in the region 450 million years ago, according to scientists.

New research pinpointing the positions of the Equator and the landmasses of the USA, Canada and Greenland, during the Ordovician Period 450 million years ago, indicates that the equator ran down the western side of North America with a hurricane belt to the east.

The hurricane belt would have affected an area covering modern day New York State, New Jersey and most of the eastern seaboard of the USA.

An international research team led by Durham University used the distribution of fossils and sediments to map the line of the Ordovician Equator down to southern California.

The study, published in the journal Geology,is the first to accurately locate and map the ancient Equator and adjacent tropical zones. Previous studies had fuelled controversy about the precise location of the ancient equator. The researchers say the new results show how fossils and sediments can accurately track equatorial change and continental shifts over time.

Co-lead author Professor David Harper, Department of Earth Sciences, said: “The equator, equatorial zones and hurricane belts were in quite different places in the Ordovician. It is likely that the weather forecast would have featured frequent hurricane-force storms in New York and other eastern states, and warmer, more tropical weather from Seattle to California.”

Since Polar Regions existed 450 million years ago, the scientists believe that there would have been similar climate belts to those of today.

The research team from Durham University and universities in Canada, Denmark and the USA, discovered a belt of undisturbed fossils and sediments -deposits of shellfish- more than 6000 km long stretching from the south-western United States to North Greenland. The belt also lacks typical storm-related sedimentary features where the deposits are disturbed by bad weather. The researchers say that this shows that the Late Ordovician equatorial zone, like the equatorial zone today, had few hurricane-grade storms.

In contrast, sedimentary deposits recorded on either side of the belt provide evidence of disturbance by severe storms. Hurricanes tend to form in the areas immediately outside of equatorial zones where temperatures of at least 260C combine with Earth’s rotation to create storms. The researchers believe that hurricane belts would probably have existed on either side of the ancient equator, within the tropics.

The position of the equatorial belt, defined by undisturbed fossil accumulations and sediments, is coincident with the Late Ordovician equator interpreted from magnetic records (taken from rocks of a similar age from the region). This provides both a precise equatorial location and confirms that Earth’s magnetic field operated much in the same way as it does today.

The scientists pieced together the giant jigsaw map using the evidence of the disturbed and undisturbed sedimentary belts together with burrows and shells. Using the findings from these multiple sites, they were able to see that North America sat on either side of the Equator.

Co-author Christian Rasmussen, University of Copenhagen, said: “The layers of the earth build up over time and are commonly exposed by plate tectonics. We are able to use these ancient rocks and their fossils as evidence of the past to create an accurate map of the Ordovician globe.”

Professor Harper added: “The findings show that we had the same climate belts of today and we can see where North America was located 450 million years ago, essentially on the Equator.”

“While the Equator has remained in approximately the same place over time, the landmasses have shifted dramatically over time through tectonic movements. The undisturbed fossil belt helps to locate the exact position of the ancient Laurentian landmass, now known as North America.”

The study is funded by the Danish Council for Independent Research.

Date of Earliest Animal Life Reset by 30 Million Years

ScienceDaily (June 28, 2012) — University of Alberta researchers have uncovered physical proof that animals existed 585 million years ago — 30 million years earlier than previous records show.
The discovery was made by U of A geologists Ernesto Pecoits and Natalie Aubet in Uruguay. They found fossilized tracks a centimeter-long, slug-like animal left behind 585 million years ago in silty, shallow-water sediment.

A team of U of A researchers determined that the tracks were made by a primitive animal called a bilaterian, which is distinguished from other non-animal, simple life forms by its symmetry — its top side is distinguishable from its bottom side — and a unique set of “footprints.”

U of A paleontologist Murray Gingras says fossilized tracks indicate that the soft-bodied animal’s musculature enabled it to move through the sediment on the shallow ocean floor. “The pattern of movement indicates an evolutionary adaptation to search for food, which would have been organic material in the sediment,” he said.

There were no fossilized remains of a bilaterian’s body, just its tracks. “Generally when we find tracks of a soft-bodied animal, it means there’s no trace of the body because they fossilize under different conditions,” said Gingras. “It’s usually just the body or just the tracks, not both.”

It took more than two years for the U of A team members to satisfy themselves and a peer review panel of scientists that they had the right age for the bilaterian fossils.

U of A geochronologist Larry Heaman was among a group that returned to Uruguay to collect more fossil samples locked in a layer of sandstone. Heaman says because the depositional age of the sandstone is difficult to determine, they focused their investigation on particles of granitic rock found invading the sandstone samples.

Heaman explains that the granitic rocks were put through the university’s mass spectrometry equipment, a process in which samples are bombarded by laser beams and the resulting atom- to molecule-sized particles are analyzed and dated.

Over the course of his U of A career, Heaman has taken part in a number of breakthrough research projects involving fossils. Last year he got the attention of the paleontology world when he confirmed the surprising date of a fossilized dinosaur bone found in New Mexico. Using U of A equipment, Heaman determined that the bone came from a sauropod, a plant-eating dinosaur that was alive some 700,000 years after the mass-extinction event that many believe wiped out all dinosaur life on Earth.

Heaman says the challenge in dating the bilaterian fossil makes it stand out from his other work. “This was the top research accomplishment because it has more direct relevance to the evolution of life as we know it,” he said. “It was such a team effort; any one of us on our own couldn’t have done this.”

Before the U of A bilaterian find, the oldest sign of animal life was dated at 555 million years ago, from a find made in Russia.

Kurt Konhauser, a U of A geomicrobiologist, says the team’s discovery will prompt new questions about the timing of animal evolution and the environmental conditions under which they evolved.

“This research was a huge interdisciplinary effort and shows the depth of the research capabilities here at the U of A,” said Konhauser. “The challenge brought the sciences of geology, paleontology, geomicrobiology and geochronology together to nail down the age of the fossils.”

Konhauser explains that in the past, research into the earliest signs of animal life would typically shift the date back by a few million years, but the U of A’s finding of 30 million years is a real breakthrough.

The U of A’s research team includes Ernesto Pecoits, Natalie Aubet, Kurt Konhauser, Larry Heaman, Richard Stern and Murray Gingras. The research was published June 28 in the journal Science.

Duck-Billed Dinosaurs Endured Long, Dark Polar Winters

ScienceDaily (Apr. 11, 2012) — Duck-billed dinosaurs that lived within Arctic latitudes approximately 70 million years ago likely endured long, dark polar winters instead of migrating to more southern latitudes, a recent study by researchers from the University of Cape Town, Museum of Nature and Science in Dallas and Temple University has found.

The researchers published their findings, “Hadrosaurs Were Perennial Polar Residents,” in the April issue of the journal The Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology.

Anthony Fiorillo, a paleontologist at the Museum of Nature and Science, excavated Cretaceous Period fossils along Alaska’s North Slope. Most of the bones belonged to Edmontosaurus, a duck-billed herbivore, but some others such as the horned dinosaur Pachyrhinosaurus were also found.

Fiorillo hypothesized that the microscopic structures of the dinosaurs’ bones could show how they lived in polar regions. He enlisted the help of Allison Tumarkin-Deratzian, an assistant professor of earth and environmental science, who had both expertise and the facilities to create and analyze thin layers of the dinosaurs’ bone microstructure.

Another researcher, Anusuya Chinsamy-Turan, a professor of zoology at the University of Cape Town, was independently pursuing the same analysis of Alaskan Edmontosaurus fossils. When the research groups discovered the similarities of their studies, they decided to collaborate and combine their data sets to provide a larger sampling. Half of the samples were tested and analyzed at Temple; the rest were done in South Africa.

“The bone microstructure of these dinosaurs is actually a record of how these animals were growing throughout their lives,” said Tumarkin-Deratzian. “It is almost similar to looking at tree rings.”

What the researchers found was bands of fast growth and slower growth that seemed to indicate a pattern.

“What we found was that periodically, throughout their life, these dinosaurs were switching how fast they were growing,” said Tumarkin-Deratzian. “We interpreted this as potentially a seasonal pattern because we know in modern animals these types of shifts can be induced by changes in nutrition. But that shift is often driven by changes in seasonality.”

The researchers questioned what was causing the dinosaurs to be under stress at certain times during the year: staying up in the polar region and dealing with reduced nutrition during the winter or migrating to and from lower latitudes during the winter.

They did bone microstructure analysis on similar duck-billed dinosaur fossils found in southern Alberta, Canada, but didn’t see similar stress patterns, implying that those dinosaurs did not experience regular periodic seasonal stresses. “We had two sets of animals that were growing differently,” said Tumarkin-Deratzian.

Since the Alaska fossils had all been preserved in the same sedimentary horizon, Fiorillo examined the geology of the bonebeds in Alaska where the samples were excavated and discovered that these dinosaurs had been preserved in flood deposits.

“They are very similar to modern flood deposits that happen in Alaska in the spring when you get spring melt water coming off the Brooks Mountain Range,” said Fiorillo. “The rivers flood down the Northern Slope and animals get caught in these floods, particularly younger animals, which appear to be what happened to these dinosaurs.

“So we know they were there at the end of the dark winter period, because if they were migrating up from the lower latitudes, they wouldn’t have been there during these floods,” he said.

“It is fascinating to realize how much of information is locked in the bone microstructure of fossil bones,” said Chinsamy-Turan. “It’s incredible to realize that we can also tell from these 70 million-year-old bones that the majority of the polar hadrosaurs died just after the winter season.”

The study was funded through a grant from the National Science Foundation.

Two New Extinct Camel Species Discovered at Panama Canal Excavation

ScienceDaily (Feb. 29, 2012) — The discovery of two new extinct camel species by University of Florida scientists sheds new light on the history of the tropics, a region containing more than half the world’s biodiversity and some of its most important ecosystems.

Plants & Animals
Fossils & Ruins

Appearing online this week in the Journal of Vertebrate Paleontology, the study is the first published description of a fossil mammal discovered as part of an international project in Panama. Funded with a grant from the National Science Foundation, UF paleontologists and geologists are working with the Panama Canal Authority and scientists at the Smithsonian Tropical Research Institute to make the most of a five-year window of excavations during Panama Canal expansions that began in 2009.

The discovery by Florida Museum of Natural History researchers extends the distribution of mammals to their southernmost point in the ancient tropics of Central America. The tropics contain some of the world’s most important ecosystems, including rain forests that regulate climate systems and serve as a vital source of food and medicine, yet little is known of their history because lush vegetation prevents paleontological excavations.

“We’re discovering this fabulous new diversity of animals that lived in Central America that we didn’t even know about before,” said co-author Bruce MacFadden, vertebrate paleontology curator at the Florida Museum on the UF campus and co-principal investigator on the NSF grant funding the project. “The family originated about 30 million years ago and they’re found widespread throughout North America, but prior to this discovery, they were unknown south of Mexico.”

Researchers described two species of ancient camels that are also the oldest mammals found in Panama: Aguascalietia panamaensis and Aguascalientia minuta. Distinguished from each other mainly by their size, the camels belong to an evolutionary branch of the camel family separate from the one that gave rise to modern camels based on different proportions of teeth and elongated jaws.

“Some descriptions say these are ‘crocodile-like’ camels because they have more elongated snouts than you would expect,” said lead author Aldo Rincon, a UF geology doctoral student. “They were probably browsers in the forests of the ancient tropics. We can say that because the crowns are really short.”

Rincon discovered the fossils in the Las Cascadas formation, unearthing pieces of a jaw belonging to the same animal over a span of two years, he said.

“When I came back to the museum, I started putting everything together and realized, ‘Oh wow, I have a nearly complete jaw,’ ” Rincon said.

The study shows that despite Central America’s close proximity to South America, there was no connection between continents because mammals in the area 20 million years ago all had North American origins. The Isthmus of Panama formed about 15 million years later and the fauna crossed to South America 2.5 to 3 million years ago, MacFadden said.

Barry Albright, a professor of earth science at the University of North Florida who studied the early Miocene fauna of the Gulf Coast Plain, said he was surprised by the similarity of the Central American fauna.

“To me, it’s slightly unexpected,” Albright said. “That’s a large latitudinal gradient between the Gulf Coastal Plain and Panama, yet we’re seeing the same mammals, so perhaps that tells us something about climate over that interval of time and dispersal patterns of some mammals over that interval of time.”

Camels belong to a group of even-toed ungulates that includes cattle, goats, sheep, deer, buffalo and pigs. Other fossil mammals discovered in Panama from the early Miocene have been restricted to those also found in North America at the time. While researchers are sure the ancient camels were herbivores that likely browsed in forests, they are still analyzing seeds and pollen to better understand the environment of the ancient tropics.

“People think of camels as being in the Old World, but their distribution in the past is different than what we know today,” MacFadden said. “The ancestors of llamas originated in North America and then when the land bridge formed about 4 to 5 million years ago, they dispersed into South America and evolved into the llama, alpaca, guanaco and vicuña.”

Researchers will continue excavating deposits from the Panama Canal during construction to widen and straighten the channel and build new locks, expected to continue through 2014. The project is funded by a $3.8 million NSF grant to develop partnerships between the U.S. and Panama and engage the next generation of scientists in paleontological and geological discoveries along the canal. Study co-authors include Jonathan Bloch of UF, and Catalina Suarez and Carlos Jaramillo of the Smithsonian Tropical Research Institute.