An Ice Age Gave Dog Domestication the Cold Shoulder

Regarded as “mans best friend” dogs have had an extraordinary relationship with humans and as a result can be regarded as one of the most successful types of mammal on the planet.  A new study suggests that mankind’s close relationship with dogs began as early as 33,000 years ago.  However, an Ice Age that started approximately 26,000 years ago; which resulted in dramatically changing climatic conditions over much of the Northern Hemisphere interrupted this domestication process.  It was not until the climate became milder and more stable some 7,000 years later did the dog/mankind relationship start up again in earnest.

Dog Domestication

In a new study published in the online scientific journal PLoS ONE (Public Library of Science) researchers claim that although dogs had started to become domesticated at least 33,000 years ago, these canines did not produce descendants that survived beyond the Ice Age.

The theory, based on the analysis of the 33,000-year-old remains of a dog that may have been a partly domesticated, explains why the remains of possible prehistoric dogs date to such early periods, and yet all modern dogs appear to be descended from ancestors that lived at the end of the Ice Age 17,000-14,000 years ago.  How and why creatures such as wolves began to associate with people has been the subject of debate for a long time.  In Darwin’s time it was thought that domesticated dogs originated from a number of wild stocks, however, modern genetics indicates that all dogs today can trace their ancestry back to the wolf.  Wolves and humans have a surprising amount in common, especially when their roles as predators are considered.  For example, humans and wolves hunt in daylight, both are social creatures and use vision as an important sense when attacking prey.  They also preyed on the same types of animal – the mega herbivores as they are known.  It is likely that wolves began to associate with humans getting scraps from kills and slowly but surely the path towards domestication began to be taken.

The 33,000 doggy remains were found in a cave in the Altai Mountains of southern Siberia (Razboinichya cave).  It was found amongst other wild animal bones but was the only dog-like creature found.

Susan Crockford, co-author of the study stated:

“The Razboinichya dog find demonstrates that the right wolf/human conditions suitable for getting domestication started were present at least 33,000 years ago.  However, such conditions would have had to be present continuously [stable climatic conditions] for many wolf generations, for the domestication process to generate a true dog.”

An on-going Russian study into foxes has been testing how quickly wild animals can become domesticated. The study has been operating for many years, with each generation of fox cubs selected for tameness, with these animals being allowed to breed with other foxes that although show a degree of domestication.  Over many generations of foxes the Russian scientists have been able to produce a fox that behaves in a very similar way to domesticated dogs.

Susan Crockford, a researcher at Pacific Identifications Inc. added:

“It appears that such stable conditions were not present until after the Ice Age, sometime after 19,000 years ago,.  Even after the Ice Age, domestication of wolves could have got started at several different times and places, and still failed because the conditions were not continuous enough for the changes to become permanent.”

The Siberian animal was unearthed some years ago, but was only recently dated to 33,000 years ago by three independent radiocarbon dating facilities.  Crockford and her colleagues conclude that it was a partly domesticated dog because of its mixture of dog and wolf features.  It was about the size and shape of a large male Samoyed dog, so it was smaller than a European wolf, but its teeth were still wolf-sized. The scientists have concluded that it “probably behaved more like a wolf than a dog.”

Its remains were excavated from a cave area containing wild animal bones. Usually fully domesticated dogs, even very early ones, received more careful burials, often being placed in graves with, or next to, their owners.  In fact, a recent discovery may indicate that the fox Vulpes vulpes may have been early man’s best friend.

To read an article about the discovery of a fox buried with humans in a Mesolithic grave: Is the Fox Man’s Best Friend?

Since no other dog-like animals were found at the site, the researchers think this animal was an “incipient” dog in the early stages of domestication.  The scientists hold that domestication can happen naturally, without direct human intervention, when wolves are attracted to settlements and gradually adjust to a human-dependent lifestyle, relying on people for scraps of food and such like.  Certainly, if a wolf-like animal could be domesticated it would have had tremendous benefits for people.  These dogs could have acted as watch dogs, helping to keep people safe from other wild animals, they could have assisted in hunting and, for anyone who has had a dog curl up on their feet, as wolves have a higher body temperature than humans they would have been very good at keeping us warm at night.

The Ice Age, however, changed the abundance and migration patterns of the animals that the people in the Altai Mountains of Siberia hunted for food.  The researchers conclude that with the climate change, people would have been more nomadic and this would have interrupted any domestication of wolves.

Without the conditions that fuel domestication, the dog or dog-like animals gradually died off, the researchers suspect.  Dogs reemerged after the Ice Age, reproducing and becoming the ancestors to today’s modern dogs.  It is unclear when the first pre-Ice Age dogs emerged, but a dog-like skull dating to 36,500 years ago was found at Goyet Cave in Belgium.  It’s possible then that the first dogs appeared in parts of Europe and Asia much earlier than commonly thought.  Many scientists do believe that the wolf was the first animal to be domesticated by mankind, and may partially explain why dogs and humans have such a special relationship, indeed dogs do seem to have developed some unique ways of understanding our moods and communicating with us.  After all, it is now thought that the dog “bark” was adopted by dogs so that they could communicate with humans – wolves don’t bark as a rule.

Other scientists have queried these research results and have suggested that more fossil specimens will be needed to prove conclusively the theory postulated by Susan Crockford and her colleagues.  Without more specimens,  it cannot be ruled out that the Siberian dog, and possibly some of the other pre-Ice Age animals, were different representatives of now-extinct wolves.

Richard Meadow, director of the Zooarchaeology Laboratory at Harvard University’s Peabody Museum, expressed his reservations about the study’s conclusions.

Crockford admits that the paper presents “a new way of thinking about domestication, but it fits the evidence better than the idea that people deliberately created dogs for some specific purpose.”

We await to see what lies lurking in the depths of the caves of the Altai Mountains, perhaps an ancient dog collar or maybe a rubber bone anyone?

Visit Everything Dinosaur’s website: Dinosaur Models, Toys and Games.

Eucalyptus Fossils from Argentina

Eucalyptus trees may be restricted to Australia and its outlying islands these days but new fossil evidence suggests that this ancient type of tree may have flourished in South America.  Fossils of leaves, flowers, fruits and buds found in Patagonia (Argentina) indicate that this type of tree was around in the Palaeogene and they represent the only scientifically validated Eucalyptus fossils (macro-fossils), identified from outside Australasia.

The fossils have been dated to approximately 52 million years ago and represent a sub-genus of Eucalyptus known as Symphyomyrtus, which makes this sub-genus much more ancient than previously thought.

Eucalyptus Fossil

The research team identified a number of structures characteristic of Eucalyptus in the morphology (shape) of imprints of plant material preserved as fossils.  Some key features included, long, thin leaves with smooth edges, dots on the leaves that reveal oil glands and scars on the fruits where petals and sepals fell off

The evolution of the Eucalyptus and its relatives has been poorly documented, due to the lack of fossil evidence.  In the past, a few scientists had claimed to identify Eucalyptus fossils from South America but those records failed to hold up to formal scientific scrutiny using modern research techniques.

Maria A. Gandolfo, a senior researcher in the Dept. of Plant Biology at Cornell University and one of the lead authors on the paper stated:

“The genus Eucalyptus is restricted to Australia and a few surrounding islands, and it is completely extinct in South America which makes this discovery very significant not only for botanists and palaeobotanists but also for [its] biogeographical implications.”

The fossils were found at a site called Laguna del Hunco, north-western Chubut Province in Patagonia.  Although petroleum exploration geologists first discovered fossils at this site in 1932, a team of researchers from the United States and Argentina including Gandolfo and Elizabeth Hermsen, a postdoctoral associate working in Gandolfo’s lab, collected important fossils in 2009 that included fruits, branching structures that support the fruits, three flower buds and a flower.

Elizabeth, who is also a lead author on the scientific paper detailing the research team’s work said:

“The buds provided important information that placed them within the genus Eucalyptus; they really helped clinch the identity of the fossils.”

Depicting the Evolutionary Relatedness in Groups of Organisms

The researchers also used a computer programme and analysis of the morphology to create a phylogeny, a branching diagram that depicts the evolutionary relatedness among groups of organisms (species, populations and so on), of Eucalyptus.  Because the researchers were able to accurately date the fossils and then place them in a phylogenetic context in relation to living plants, the findings may now be used as a reference point to test the results of recent molecular dating studies that have calculated the age of the Eucalypts.

The research was conducted in collaboration with colleagues from Pennsylvania State University, the Denver Museum of Nature and Science, the Universidad de Buenos Aires and Museo Paleontológico E. Feruglio, Argentina.  The work was funded by an American Recovery and Reinvestment Act Grant from the National Science Foundation to Gandolfo.

For models of prehistoric trees and plants as well as prehistoric animals: Models of Prehistoric Plants and Prehistoric Creatures (CollectA).

Early Duck-billed Dinosaur Discovery Adds to Debate over Evolution of Hadrosauridae Crests

Scientists have a new clade of duck-billed dinosaur to study, and thanks to two almost simultaneous fossil discoveries in the United States; more information on the evolution of Hadrosauridae head crests could emerge as well as a better understanding of the geographical distribution of ornithischian genera in the western United States during the Late Cretaceous.

Duck-billed Dinosaur

The duck-billed dinosaurs, so called as they had beaks that resembled the broad beaks of a duck, were a very successful group of plant-eating dinosaurs that evolved during the Cretaceous and rapidly diversified into numerous genera.  These types of dinosaur are broadly divided into two main sub-families, the hollow crested Lambeosaurinae and the predominately solid crested or crest absent – Hadrosaurinae.  The discovery of a new genus of duck-billed dinosaur named Acristavus gagslarsoni has led to the establishment of a new clade of hadrosaurs, the Brachylophosaurini and may shed light on the origins of these dinosaurs and how they diversified into two main sub-families.

Acristavus gagslarsoni

The first fossil specimen was found in Montana in 1999 by the Old Trail Museum staff and volunteers, including a group of “junior palaeontologists” from the University of Chicago and was excavated in 2001 and 2002 from the Two Medicine Formation (Montana) by study co-author Rebecca Hanna for the Museum of the Rockies in Bozeman, Montana, where it now resides.  By an extraordinary coincidence, a second specimen of the same dinosaur species was discovered just a a year after the Montana specimen (2000).

This discovery was made in the Grand Staircase Escalante National Monument strata (Wahweap Formation – southern Utah) by an entomologist from Brigham Young University C. Riley Nelson (who has also co-authored the published paper on this new dinosaur with Rebecca).

The strata at these two sites date from the same geological time (Campanian faunal stage) and the two finds have been dated to approximately 79 million years ago.  This makes A. gagslarsoni the oldest known hadrosaur from North America and it is remarkable that two specimens of the same dinosaur species were found within a year of each other, but at locations more than six hundred miles apart.

A Wandering Hadrosaur

Terry Gates, a research associate at the Chicago Field Museum stated:

“To find two specimens six hundred and fifty miles apart that lived at virtually the same time, and were discovered within a year of each other is extremely rare in dinosaur palaeontology”.

With elements of the skull to study including the frontal and postorbital bones along with the dentary (lower jaw) scientists have noted that there is a lack of any cranial ornamentation (no crest),  which is in stark contrast to virtually every other of genus of hadrosaur dinosaur discovered to date.  This discovery, an early type of hadrosaur, what is believed to be a basal North American duck-billed dinosaur lacking any form of head crest or ornamentation adds weight to the theory that the two sub-families of this type of dinosaur, the Lambeosaurinae and the Hadrosaurinae independently evolved head crests and ornamentation.

As for explaining why the fossils were found so far apart a spokesperson for Everything Dinosaur commented:

“There could be a number of reasons why these specimens were found so far apart.  For example, most scientists believe that these dinosaurs lived in herds and they may have made extensive migrations in search of seasonal feeding opportunities or indeed travelling to favoured nesting sites.  Secondly, this type of basal hadrosaur may have had a wide geographical distribution, perhaps it had an inherent advantage over other types of plant eating dinosaur around at the time, which made this particular type or herbivore very successful.”

A Simplified Hadrosaur Family Tree

Tracing the Evolution of Duck-Billed Dinosaurs.

Picture credit: Everything Dinosaur

The Brachylophosaurini consists of three hadrosaur genera, Acristavus plus Maiasaura, whose fossils have also been found in Montana and Brachylophosaurus from which the clade gets its name. This dinosaur was again widely distributed with a known range from Montana in the south to Alberta (Canada), in the north.  These dinosaurs together constitute the earliest clade of North American hadrosaurs.

The Acristavus fossils indicate that this dinosaur had anatomical characteristics seen in both Brachylophosaurus and Maiasaura specimens, but not necessarily shared between them.  This suggests that Acristavus may be ancestral to these other dinosaur genera

To view models and replicas of duck-billed dinosaurs including members of the Hadrosaurinae: Hadrosaurinae Dinosaur Models and Prehistoric Animal Figures.