Image right: The hand print of a baby dinosaur from the nesting site in South Africa. (Images courtesy University of the Witwatersrand)

A new study, entitled Oldest known dinosaur nesting site and reproductive biology of the Early Jurassic sauropodomorph Massospondylus and published in the international journal Proceedings of the National Academy of Sciences, was led by Canadian palaeontologist Robert Reisz, a professor of biology at the University of Toronto at Mississauga, and co-authored by Hans-Dieter Sues of the Smithsonian’s National Museum of Natural History; Eric Roberts of James Cook University, Australia; and Adam Yates of the Bernard Price Institute for Paleontological Research.

The study reveals clutches of eggs, many with embryos, as well as tiny dinosaur footprints, providing the oldest known evidence that the hatchlings remained at the nesting site long enough to at least double in size.

The authors say the newly unearthed dinosaur nesting ground is more than 100 million years older than previously known nesting sites.

Image left: A fossil from the nesting site showing seven eggs, some with the embryos exposed.

At least 10 nests have been discovered at several levels at this site, each with up to 34 round eggs in tightly clustered clutches. The distribution of the nests in the sediments indicate that these early dinosaurs returned repeatedly (nesting site fidelity) to this site, and likely assembled in groups (colonial nesting) to lay their eggs, the oldest known evidence of such behavior in the fossil record.

The large size of the mother, at six meters in length, the small size of the eggs, about six to seven centimetrs in diameter, and the highly organized nature of the nest, suggest that the mother may have arranged them carefully after she laid them.

“The eggs, embryos, and nests come from the rocks of a nearly vertical road cut only 25 meters long,” Reisz says. “Even so, we found ten nests, suggesting that there are a lot more nests in the cliff, still covered by tons of rock. We predict that many more nests will be eroded out in time, as natural weathering processes continue.”

Image right: A nest of dinosaur eggs from the South African nesting site.

The fossils were found in sedimentary rocks from the Early Jurassic Period in the Golden Gate Highlands National Park in South Africa. This site has previously yielded the oldest known embryos belonging to Massospondylus, a relative of the giant, long-necked sauropods of the Jurassic and Cretaceous periods.

“This amazing series of 190 million year old nests gives us the first detailed look at dinosaur reproduction early in their evolutionary history, and documents the antiquity of nesting strategies that are only known much later in the dinosaur record,” says Evans.

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As a coastal archaeologist and expert in prehistoric and historic settlement sites in the Chesapeake Bay region, Darrin Lowery of the Smithsonian’s National Museum of Natural History and University of Delaware, is carefully watching the effects of coastal erosion and rising sea levels on coastal archaeological sites. As sea levels creep slowly upward, scores of these sites are slipping under water and becoming more difficult, if not impossible, to excavate and study.

Image right: Darrin Lowery examines soils and peat marsh for evidence of ancient landscapes and sea level rise on the Mockhorn Island in Virginia. (Photo by Mike Hardesty, Washington College)

Of equal concern, says Lowery, are the chemical processes that accompany rising seas, which can modify and deteriorate the stone tools that early Americans used to hunt and prepare food and clothing hundreds of years ago. Lowery is co-author of a recent paper in the Journal of Archaeological Science on the geochemical impacts to prehistoric artifacts in coastal zones. He recently answered a few questions about his work.

Q. How do the chemical processes of sea level rise affect primitive stone tools?

A. Slowly rising sea levels result in the regular input of sediment and organic matter into low-lying areas, essentially creating areas covered in tidal marsh. Sulfidization in a tidal marsh is a process that reduces iron to its ferrous state and produces pyrite, turning stone artifacts black. A prehistoric projectile point made of jasper that has been exposed to sulfidization looks like it is made of a different type of stone called chert. This is a challenge to archaeologists because it is generally assumed that broad lithic categories can be distinguished between stone tools that are made of either chert or jasper. Over time this process can change the look of a stone artifact both inside and out.

Image left: Jasper (A) and chert (B) projectile points found at eroding shoreline sites in the Middle Atlantic. (Images courtesy Darrin Lowery)

A second process common in salt marshes is sulfuricization, which creates sulfuric acid. Highly corrosive, this acid attacks the silicate structure of a stone tool, first staining the rock with a reddish brown color and eventually causing the artifact to decompose. Having these artifacts disappear from the historic record is also of great concern to archaeologists. For a museum curator, safely storing iron-rich stone tools or artifacts that have been exposed to acid sulfate is problematic.

Q. Is sea level rise the only culprit in these changes?

A. No. The widespread practice of dredging sediment from the bottom of estuaries or along the coast and using it to build up shorelines and create living coastlines and areas for housing developments can create a situation that results in a sulfuric-acid producing machine. Marine sediments that have been oxygen-starved for several millenia are dredged up, brought to the surface and exposed to oxygen. Aerobic bacteria working on the sulfates in the sediments create sulfuric acid, as well as a series of iron oxides. If the acid is dissolving silica in iron-rich prehistoric stone tools from archaeological sites on the coast, as I have witnessed, I can only imagine how it is impacting marine life in the area adjacent to the dredge spoils.

Image right: This freshly broken projectile point made of jasper reveals the gradual precipitation of pyrite into its core, a process that has dramatically changing its color.

Q. Can you determine how much sea levels have risen since prehistoric times in North America 1,000 years ago?

A. Humans don’t like to get their feet wet so we know that prehistoric coastal sites now underwater or buried in a tidal marsh were once terrestrial, and that people were once eating, sleeping and living on these spots. Because we know that some prehistoric settlement sites in the Chesapeake Bay area are situated beneath a meter of tidal marsh peat, we can use certain “known-age” iron-rich artifacts from these submerged coastal sites to assess rates of sea level rise, as well as the rates of acid sulfate chemical change. From this we can also gauge the accuracy of the reported sea level rise rates over the past few centuries.

Surveying a large number of drowned prehistoric sites gives us the opportunity to understand those rates and the reported magnitudes.

Q. Are your projects in the Chesapeake region only focused on prehistoric settlement sites?

A. With one of my research projects, I am trying to assess the reported historic rates of sea level rise using, in part, farm fields next to tidal marshes that were first plowed long ago. We have numerous detailed historic maps showing the topographically low tidal marsh areas around the Chesapeake Bay. These maps, which encompass the last 165 years, show many tilled upland hummocks surrounded by tidal marsh. Agriculturally mixed soils are a distinctive archaeological feature formed when the thin organic soil has been turned and thickened by the plow. Back in the 17th, 18th, and 19th centuries, farmers in these low tidal marsh areas around the Chesapeake Bay didn’t have much land and they cleared every upland area right up to the edge of the marsh for cultivation. The 1840s and 1850s coastal survey maps clearly show the tilled field boundaries and historic structures on these upland hummocks.

Image left:  The chemical processes that accompany rising seas is evident on the two halves of this jasper biface projectile point. The top of this artifact was found along the eroded forested upland (B). The bottom part (C) was altered by geochemical processes in the eroded upland area surrounded by tidal marsh (D) where it was found.

I’m geo-referencing these historic maps and overlaying them with recent satellite images to form a single comparative map. By doing this I can see the historic distribution of plowed fields and farms in these low coastal areas and compare them with today. Fieldwork in these areas has allowed me to relocate the historic plowed or tilled field boundaries. Many of the shorelines have been eroded by the effects of wind and waves. However, the historic plowed fields have not been inundated or covered by tidal marsh peat over the past 150 years.

What I’ve observed is that sea levels in the Chesapeake Bay may have come up a little bit in the last 150 years but I don’t believe they have risen as much as one foot, as some groups are reporting. In all my years of shoreline surveys I have never seen a 17th, 18th, or 19th century domestic site beneath a covering of tidal marsh peat. I think people are mistaking shoreline erosion and land loss, caused by wind and water chewing away at unconsolidated terrestrial sediments, with sea level rise.

For example, currently at Kent Narrows in the Chesapeake, a series of hummocks above sea level appear as upland landscapes with the same dimensions on the earlier 1840s coastal maps. Also on the Chesapeake’s Hoopers Island are a series of hummocks that were being tilled in the 1840s, the plowed landscape features are still there adjacent to the marsh and above sea level. I have observed the same conditions on Messongo Creek on Virginia’s eastern shore.

If sea levels had risen as much as one foot over the past century, the aerial extent of these isolated upland landforms should have shrunk in size and the historic plow zones associated with the hummocks should have been covered or partially covered by expanding tidal marsh.

It is important to remember that sediment erosion along shorelines does not equate to sea level rise and sediment accretion along shorelines does not equate to a sea level fall. As an example, Sharp’s Island at the mouth of the Choptank River consisted of more than 700 acres of land in 1847, but by the mid-1950’s the island had completely eroded away. Meanwhile, in 1849, Fisherman’s Island at the mouth of the Chesapeake Bay on Virginia’s eastern shore did not exist. Fisherman’s Island today consists of more than 1,800 acres of land and the island also has an extensive forested upland.

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Discovered with a nearly complete skeleton, the feathers retained enough microscopic structure to allow the scientists to confirm the classification of the bird, known by its scientific name Apteribis sp, as a close relative of the American white ibis and scarlet ibis. DNA analysis confirmed this classification.

Image left: Skull (top) and (below) detail of feathers adhering to the cranium of Apteribis sp. from Lanai, Hawaii Islands (Photo courtesy Carla Dove)

Remarkably, the feathers also retained enough pigmentation to allow Dove and Olson to determine the bird had been brown-black to ivory-beige/light brown in color. Before now, any reconstruction of the appearance of a prehistorically extinct Hawaiian bird had been only speculation.

Image right: This scanning electron photomicrograph shows the prongs on the downy barbules of an Apteribis sp. feather. (Photo courtesy Carla Dove)

Apteribis sp. is one of only two species of ibises, both now extinct, known to be flightless. Its skeleton differs so much from its mainland ancestors that the bird’s relationship to other ibises could only be determined through the study of its feathers and DNA analysis, Olson says.

The find is highly unusual because “feathers do not preserve well and often decay before a bird is fossilized,” Dove says. “These weren’t fossil imprints in a rock, but feathers and bones we could actually pick up.”

Exceptional geologic circumstances led to the preservation of the feathers inside a lava cave on the Hawaiian Island of Lanai. The floor of the cave was partially covered in a deep layer of flaky gypsum crystals, which, for hundreds of years absorbed humidity in the cave and created an arid environment ideal for preservation of the feathers. The crystals were shaken off of the walls and ceiling of the lava tube by seismic tremors.

Image right: American white ibis (Photo by Terry Foote at en.wikipedia); below, scarlet ibis (Photo by Hans Hillewaert). Both of these birds are closely related to the extinct Apteribis sp., which did not fly.

From a taxonomic standpoint feathers are significant because the shape of microscopic barbs on specific areas of a feather have distinct features that taxonomists can use to determine what bird group it belongs to, Dove says.

“The barbs are unique only on the downy, fluffy part at the base of the feather, not at the tip,” Dove says. “These microstructures are similar among orders of birds—pigeons, ducks, songbirds, for example.

Using the extensive collections in the Division of Birds at the National Museum of Natural History, Dove compared the microscopic structures of the ancient feathers (which she describes as “short barbules with these long prongs,”) to those of modern day birds.

Her analysis confirmed that Apteribis sp. is most closely related the New World ibises of the genus Eudocimus, the American white ibis (Eudocimus albus) and scarlet ibis (Eudocimus buber). Apteribis sp. was first described from fossils found on the Hawaiian Islands of Molokai and Maui. It is one of dozens of bird species known to have gone extinct following the arrival of humans on the Hawaiian Islands.

“Fossil Feathers from the Hawaiian Flightless Ibis (Apteribis SP.): Plumage Coloration and Systematics of a Prehistorically Extinct Bird,” by Carla Dove and Storrs Olson appeared in the September 2011 issue of the Journal of Paleontology.

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This illustration by Carl Buell depicts Ocucajea picklingi (center) and Supayacetus muizoni (bottom), two ancient whales that lived off the Peruvian coast during the Eocene, between 56-34 million years ago.  At top is an unnamed whale and the fossil penguin Perudyptes devriesi. Nicholas Pyenson, paleobiologist at the Smithsonian’s National Museum of Natural History, helped discover fossils of these whales in Peru’s Pisco Basin. Read his account of the discovery on this Ocean Portal blog post.

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The dodo’s large size and inability to fly were adaptations that allowed this bird to survive some of the most hostile conditions and climactic events imaginable. Only in the 1600s did a force more deadly than extreme drought and volcanic eruptions lead to its extinction: humans.

Image right: Painting of a dodo head by Cornelis Saftleven. Done in 1638,  this painting may be one of the last illustrations made of a live dodo. (Image from Boijmans Museum, Rotterdam)

In a recent paper in the journal “The Holocene” a team of scientists detail the extreme conditions that caused the death of some 500,000 animals on Mauritius during the mid-Holocene at around 4000 years ago. The evidence is a thick bed of fossil bones on Mauritius that spans an area of about 5 acres—the site of a former freshwater lake bed. The fossil layer is dominated by the remains of thousands of dodos and giant tortoises, as well as many small reptiles and flying birds.

Image left: Dodo bone in a matrix of mud, seed and other fossils excavated in a dry lake bed on the Island of Mauritius. (Image copyright Kenneth Rijsdijk/Dodo Research Programme)

Using radiocarbon dating of the bones, oxygen isotope analysis of geologic features on Mauritius and nearby islands, and the study of the island’s water table, the scientists determined the animals died during an extreme drought that lasted several decades. “Dodos, tortoises, lizards and other animals gathered here because the lake was one of the few sites on the island with fresh water,” says Hanneke Meijer, an ornithologist at the Smithsonian’s National Museum of Natural History and one of the paper’s co-authors.

“It is evident that a lot of animals suffered and died during this period, and their populations were greatly reduced,” Meijer continues, “but no species, including the dodo, went extinct during this extreme drought.” Fossil evidence reveals that “all animals were still living and the island’s ecosystem was intact at the time humans arrived in the 1600s.”

Image right: The excavation site on the island of Mauritius where the remains of some 500,000 animals were found, victims of an extreme drought some 4,000 years ago. (Image copyright Mikel Rijsdijk/Dodo Research Programme)

The dodo was resilient, and perfectly adapted to the island’s habitat, Meijer explains. “The island had no predators or carnivores and the dodo had no need to flee, so it lost its ability to fly. It received a reputation as stupid because it did not flee from humans” and human-introduced predators after they arrived at the dodo’s home in the 1600s.

Today, Meijer says, the forest cover on Mauritius has been reduced by 98 percent with only a few patches of original forest remaining. Considerable resources have been directed to preserving the island’s few remaining endemic species, such as the Mauritian kestrel. (The island’s giant tortoises went extinct in the 1800s when Dutch trade ships filled their holds with these long-lived animals to use as fresh meat on long voyages to and from Indonesia. “Mauritius was a popular stop because it provided fresh water and lots of food,” Meijer says)

Image left: Researchers at the Mauritius Island excavation site sieving excavated mud for small bones, teeth and plant remains. (Image copyright Mikel Rijsdijk/Dodo Research Programme)

Should another extended drought occur similar to the mid-Holocene event, it is very likely the remaining endemic species on Mauritius would not survive as the environment is so degraded. “Even many of the native plant species in the few remaining forest patches would probably perish,” Meijer says.

“With modern climate change scientists are very interested in how island animals adapt, as their ability to move to less disturbed areas is limited,” Meijer explains. “It has always been thought that animals on islands are particularly sensitive to climate change.” In the case of the dodo and other species on Mauritias, this new study reveals an island population highly resilient to climate change.

The article “Mid-Holocene (4200 kyr BP) mass mortalities in Mauritius (Mascarenes): Insular vertebrates resilient to climatic extremes but vulnerable to human impact,” appeared recently in the scientific journal “The Holocene.” (Rijsdijk, K.F., Zinke, J., de Louw, P.G.B., Hume,J.P., van der Plicht, J., Hooghiemstra, H., Meijer, H.J.M., Vonhof, H.B., Porch, N., Florens, F.B.V., Baider, C., van Geel, B., Brinkkemper, J., Vernimmen, T. & Janoo, A., 2011. Mid-Holocene (4200 kyr BP) mass mortalities in Mauritius (Mascarenes): Insular vertebrates resilient to climatic extremes but vulnerable to human impact. The Holocene, doi:10.1177/0959683611405236)

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The hatchling nodosaur fossil was donated to the Smithsonian’s National Museum of Natural History by Stanford, where it is on display to the public and also available for research.

After finding the fossil Stanford identified it as a nodosaur and called David Weishampel, a professor of anatomy at Johns Hopkins and a paleontologist and expert in dinosaur systematics. Weishampel and his colleagues established the fossil’s identity as a nodosaur by identifying a distinctive pattern of bumps and grooves on the skull. The body in the tiny fossil was only 13 cm long, just shorter than the length of a dollar bill. Adult nodosaurs are estimated to have been 20 to 30 feet long.

They then did a computer analysis of the skull shape, comparing its proportions to those of ten skulls from different species of ankylosaurs, the group that contains nodosaurs. They found that this dinosaur was closely related to some of the nodosaur species, although it had a shorter snout overall than the others. Comparative measurements enabled them to designate a new species, Propanoplosaurus marylandicus. In addition to being the youngest nodosaur ever found, it is the first hatchling of any dinosaur species ever recovered in the eastern United States.  Source: Johns Hopkins Medicine

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In a new study  in the journal Palaeontology, University of Florida and Smithsonian Tropical Research Institute scientists describe a new 20-foot extinct species discovered in the same Colombian coal mine with Titanoboa, the world’s largest snake. The findings help scientists better understand the diversity of animals that occupied the oldest known rainforest ecosystem, which had higher temperatures than today, and could be useful for understanding the impacts of a warmer climate in the future.

Image right: This illustration shows how Acherontisuchus guajiraensis, a 60-million-year-old ancestor of crocodiles, would have looked in its natural setting. Titanoboa, the world’s largest snake, is pictured in the background. (Illustration by Danielle Byerley/click to enlarge)

The 60-million-year-old freshwater relative to modern crocodiles is the first known land animal from the Paleocene New World tropics specialized for eating fish, meaning it competed with Titanoboa for food. But the giant snake could have consumed its competition, too, researchers say.

“The younger individuals were definitely not safe from Titanoboa, but the biggest of these species would have been a bit much for the 42-foot snake to handle,” said lead author Alex Hastings, a graduate student at the Florida Museum of Natural History and UF’s department of geological sciences.

Image left: University of Florida researchers unearth fossils from the 60-million-year-old Cerrejon formation in northeastern Colombia, one of the world’s largest open-pit coal mines. (Photo by Edwin Cadena)

The new species is a dyrosaurid, commonly believed to be primarily ocean-dwelling, coastal reptiles. The new adult specimens challenge previous theories the animals only would have entered freshwater environments as babies before returning to sea.

Fossils of a partial skeleton of the species, Acherontisuchus guajiraensis, show dyrosaurids were key players in northeastern Colombia and that diversity within the family evolved with environmental changes, such as an asteroid impact or the appearance of competitors from other groups, said Christopher Brochu, an associate professor of vertebrate paleontology in the department of geoscience at the University of Iowa, who was not involved in the study.

“We’re facing some serious ecological changes now,” Brochu said. “A lot of them have to do with climate and if we want to understand how living things are going to respond to changes in climate, we need to understand how they responded in the past. This really is a wonderful group for that because they managed to survive some catastrophes, but they seemed not to survive others and their diversity does seem to change along with these ecological signals.”

Image left: This photograph shows the size difference in the jawbones of two 60-million-year-old crocodile ancestors found in northeastern Colombia by University of Florida researchers.The newly described Acherontisuchus guajiraensis, top, and Cerrejonisuchus improcerus, bottom. C. improcerus was the first ancient crocodyliform found in the Cerrejon open-pit coal mine. The new species is the first known land animal from the Paleocene New World tropics specialized for eating fish. (Photo by Kristen Grace)

The species is the second ancient crocodyliform found in the Cerrejon mine of northern Colombia, one of the world’s largest open-pit coal mines. The excavations were led by study co-authors Jonathan Bloch, Florida Museum associate curator of vertebrate paleontology, and paleobotanist Carlos Jaramillo of the Smithsonian Tropical Research Institute.

“This one is related to a group that typically had these long snouts” Hastings said. “It would have had a relatively similar diet to the other (coastal) species, but surprisingly it lived in a more freshwater environment.”

The genus is named for the river Acheron from Greek mythology, “the river of woe,” since the animal lived in a wide river that emptied into the Caribbean. Unlike the first crocodile relative found in the area, which had a more generalized diet, the snout of the new species was long, narrow and full of pointed teeth, showing a specialization for hunting the lungfish and relatives of bonefish that inhabited the water.

“The general common wisdom was that ancestrally all crocodyliforms looked like a modern alligator, that all of these strange forms descended from a more generalized ancestor, but these guys are showing that sometimes one kind of specialized animal evolved from a very different specialized animal, not a generalized one,” Brochu said. “It’s really showing us a level of complexity to the history that 10 years ago was not anticipated.”

During the Paleocene in South America, the environment was dominated by reptiles, including giant snakes, turtles and crocodiles. The dyrosaurid family originated in Africa about 75 million years ago, toward the end of the age of dinosaurs, and arrived in South America by swimming across the Atlantic Ocean.

“The same thing that snuffed out the dinosaurs killed off most of the crocodiles alive at the time,” Hastings said. “The dyrosaurids are one of the few groups to survive the extinction and later become more successful.”

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Image right: Unlike other baleen whales, gray whales feed on bottom-dwelling organisms by suctioning sediments and filtering out worms and crustaceans. (Courtesy of Flip Nicklin)

The researchers, who analyzed California gray whale (Eschrichtius robustus) responses to climate change over the past 120,000 years, also found evidence to support the idea that the population of gray whales along the Pacific Coast before the arrival of humans was two to four times today’s population, which stands at about 22,000. The whale is considered a conservation success story because protections instituted as early as the 1930s have allowed populations to rebound from fewer than 1,000 individuals in the early 20th century, after less than 75 years of systematic whaling.

Image left: An 1872 illustration of a gray whale by Charles Melville Scammon.

“There almost certainly were higher gray whale populations in the past,” said evolutionary biologist David Lindberg, a UC Berkeley professor of integrative biology who coauthored the paper with his former student, Nicholas D. Pyenson, now curator of fossil marine mammals at the Smithsonian’s National Museum of Natural History in Washington, D.C. The paper appeared in the online, open-access journal PLoS ONE.

Lindberg and Pyenson suggest that higher populations in the past were possible because gray whales utilized a greater variety of food resources – resources that today’s whales are only now beginning to exploit. According to Lindberg, gray whales were once thought to feed only by suctioning seafloor sediment and filtering out worms and amphipods – so-called benthic organisms. But some whales are now eating herring and krill as well, just like their baleen whale relatives, which include the humpback and the blue.

Image right: This 19th century drawing depicts gray whales cavorting among ice floes in the norhtern Pacific Ocean. This observation suggests that gray whales can tolerate pack ice, a trait that helped it survive ice ages. (From Scammon, 1874)

Some whales are even dropping out of the migratory rat race. One group hangs out year-round off Vancouver Island in Canada, where they chase herring and krill.

“We propose that gray whales survived the disappearance of their primary feeding ground by employing generalist filter-feeding modes, similar to the resident gray whales found between northern Washington State and Vancouver Island,” the scientists write in their paper.

“A combination of low population numbers and a species migrating between places where humans didn’t bother them gave us the impression that gray whales have a stereotypical migratory and feeding behavior that may not be historically correct,” Lindberg said.

Image left: A gray whale pushing its mouth and head above the water.

The new population numbers accord with a 2007 estimate that the California gray whale population was likely 76,000 to 120,000 before humans began hunting them. That estimate, by Stephen Palumbi of Stanford University and his collaborators, was based on an analysis of gray whale genetic diversity.

The numbers clash, however, with claims by some ecologists that populations of between 15,000 and 20,000 are likely the most that the Pacific Coast – specifically along the whales’ 11,000 kilometer (6,900 mile) migratory route from Baja California to the Bering Sea – could support, today or in the past.

“Our data say that, if the higher estimates are right, gray whales would have made it through the Ice Ages in numbers sufficiently large to avoid bottlenecking,” Pyenson said. “If gray whale populations were at the lower levels, they would only have squeaked through the ice ages with populations of hundreds or a few thousand. That would have left bottlenecking evidence in their DNA.”

Bottlenecking is when populations drop so low that inbreeding becomes common, decreasing the genetic diversity in the species and making them less able to adapt to environmental change.

Gray whales are survivors

The new assessment is good news for gray whales, which appear to have “a lot more evolutionary plasticity than anyone imagined,” Lindberg said. This could help them survive the climate change predicted within the next few centuries that is characterized by an expected sea level rise of several meters.

Image right: A gray whale calf. (Photo by Patty Geary)

“I suspect the gray whales will be among the winners in the great climate change experiment,” Pyenson said.

Lindberg and Pyenson initiated the study several years ago in the face of conflicting and contentious estimates for past gray whale populations. They thought that an understanding of how gray whales adapted to climate change over the past 3 million years, the period called the Pleistocene, might provide insight into how they will adapt to climate change today.

Since gray whales arose – the oldest fossils date from 2.5 million years ago – Earth has gone through more than 40 major cycles of warming and cooling, each of which significantly affected the world’s flora and fauna. During the last glacial cold spell, between 50,000 and 10,000 years ago, most of the large terrestrial mammals disappeared through a combination of climate change and human depredation, Lindberg noted. The marine realm, however, experienced almost no extinctions and very few new originations during that same period.

--Source: Robert Sanders, University of California, Berkeley

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