Discovery of Earliest Known Fossil of a Toothless Bird Announced

The discovery of the oldest known toothless bird has been announced by Chinese scientists.  The evolution of birds and their diversification during the Late Jurassic and Cretaceous is little understood by palaeontologists.  There are very few fossils to study.  Birds with their ability to fly took to forests and wooded areas very early in their evolution, especially with so many small theropod dinosaurs running around, being up in a tree and relatively safe was a good place to be for a bird.  However, in forest environments the potential for fossil preservation is often very poor, so there are only a few fossils of early birds within the fossil record.

An Ancient Duck

The north-eastern Chinese province of Liaoning is the exception with many fine specimens of birds (and feathered dinosaurs) having been unearthed.  This new Liaoning genus, named Zhongjianornis yangi was about the size of a pigeon and like the majority of fossils found in this area, the specimen represents an individual that ended up at the bottom of a lake, covered with fine sediment which was low in oxygen and ultimately this aided preservation as a fossil.  A study of the fossil, the paper of which is due to appear in the scientific journal – Proceedings of the Royal Society B, reveals that this early bird may have been semi-aquatic, a sort of early duck.

Fossil Skeleton

To date only one fossil skeleton has been found, but it is virtually complete and like many of the other Liaoning fossils shows exceptional detail.  This particular bird had a long, pointed snout with toothless jaws, shedding new light on the evolution of that well-known feature of birds – the beak.  The Chinese team have dated this creature to approximately 120 million years ago, Early Cretaceous (Aptian faunal stage), it represents the most primitive toothless bird discovered to date.

Although the earliest known bird Archaeopteryx had a number of reptilian features including needle-like teeth in the jaws, a number of different types of bird soon lost their teeth as the Aves order diversified.  This is an example of parallel evolution, with different types of creature evolving the same solution to a common problem, in this case the need to lose weight so that flight could become more efficient.  This is an example of selective pressure to produce a lighter skeleton to aid flight.

A Replica of an Archaeopteryx Fossil

Archaeopteryx fossil cast. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

This particular primitive bird may have fed on fish, although this is speculation, the pointed snout would have helped it catch them but the lack of teeth may have made holding onto slippery prey difficult.  However, many bird species feed on fish today so this is quite possible.  There was a lot of prey in the lush forests and lakes of the Liaoning region during the Early Cretaceous.  The fossil record from Liaoning is very rich with many types of fish, amphibians, reptiles, mammals, plants and birds known, as well as the dinosaurs.

Commenting on this discovery, palaeontologist Dr Zhonghe Zhou, of the Chinese Academy of Sciences, Beijing, stated:

“Over 30 genera of Early Cretaceous birds have been reported in the last two decades from the Lower Cretaceous of north-eastern China, documenting a burst of avian diversification that followed the appearance of the earliest bird Archaeopteryx”.

This new discovery will add to our knowledge regarding the diversity of early birds.

Dr Zhou added:

“The new material is represented by a nearly complete and articulated skeleton. The new bird displays a combination of features that are unknown in any previously reported taxon; in particular, it represents the most basal avian that had completely lost teeth”.

It is very likely that the vast Liaoning deposits will yield even more strange and wonderful fossils in the future, providing scientists with an insight into life in the Mesozoic.

Visit Everything Dinosaur’s website: Everything Dinosaur.

Evidence Suggests Cave Women not Cave Men were Responsible for Cave Paintings

The contemporary image of a solitary cave man carefully painting an image of the animals he and his fellow hunters intended to catch is being challenged by a new study into European cave art. Cave women played a significant role, according to new research..

Professor Dean Snow and a team of researchers from Pennsylvania State University have compared the hand impressions left by our ancestors on cave walls with those of modern Europeans and concluded that many of the hand prints were from women.  If the prints are female, then it could be suggested that the artworks, too were by the hand of the fairer sex.  The hand print, being a symbolic gesture indicating ownership of the painting or perhaps staking a claim for recognition for their artwork, just as a painter may sign their work today.

Cave Women

Having studied the Palaeolithic paintings in French caves such as Pech Merle in south-western France and the cave at Gargas (French Pyrenees), the American team concluded that even after a “superficial” examination of published photographs there seemed to be plenty of female hands depicted on the cave walls.

Adult male hands are normally much larger in size than adult females, the smaller prints left behind by our ancestors on cave walls could have been made by woman or younger males or females.  Such a revelation could challenge our existing understanding of the role of the sexes in early human settlements.

Professor Snow and his team used measurements of the hands of modern Europeans and compared these to the measurements taken of the hands from the cave walls.  Using ratios between the digits to determine the sex, the team concluded that a number of the prints were female.

Commenting on the digit ratios, Professor Snow stated:

“The very long ring finger, it is a dead giveaway for male hands, a long index finger and a short little finger is very feminine”.

If you give a child a paint tray and ask him or her to make an impression of their hand, they normally place their hand in the paint and then press it down on the paper to make an impression of the hand.  However, cave paintings depicting hands were made very differently.  Hand prints were not used, instead the hand was used as a sort of stencil.

Scientists have suggested two techniques, firstly the hand was placed on the area of wall where the imprint was required and the paint spat out of the mouth to create a stencil affect.  An alternative method of using a straw to blow the pigment-like paint onto the wall has also been proposed.

CollectA Neanderthal Models (Cave Man and Cave Woman)

CollectA Neanderthal models.

To view the CollectA model collection: CollectA Age of Dinosaurs Popular Models.

Many of the cave paintings have been dated to between 40,000 and 20,000 years ago.  If the artwork was made by women, then the current thinking regarding the role of females in cave society will have to be re-examined.  Indeed, the artwork may have had a different purpose than that assumed previously.  Many of the pictures depict oxen, horses and antelope, the sort of animals that our ancestors hunted.  If the artwork was produced by the women of the clan, did they also participate in the actual hunts?  Images of people hunting left on cave walls have always been interpreted as male, but perhaps if the role of women was greater in ancient cave clan society, perhaps they also took part in hunts.

Dinosaur Size Linked to their Lifestyle and Availability of Food

No sooner have papers been published suggesting that the body weights of dinosaurs may have been overestimated, a new report has just come out suggesting that dinosaurs got so big simply because the resources in their environment allowed them to do so.

Recently, the accepted methodology for estimating the mass of dinosaurs has been challenged.  Heavyweight dinosaurs such as Apatosaurus and Diplodocus have had their estimated body weights reduced using a new mathematical formula.  Now zoologists from the University of Florida have published research that indicates that dinosaurs were the “couch potatoes” of the Mesozoic.

To read the article challenging the accepted methods for calculating the weight of dinosaurs: Dinosaurs were “Thinosaurs” – A weighty issue.

Dr McNab and his team have argued that with easy access to abundant food and a sedentary lifestyle dinosaurs were able to grow into the biggest land living animals known in the fossil record.  A number of theories have been put forward suggesting why dinosaurs were able to grow so big.  For example, natural selection may have favoured bigger and bigger animals through predation pressure and the need to fight to secure a mate.  Or being large may have helped dinosaurs regulate their body temperatures, as large animals with a greater surface area to body mass ratio are generally able to maintain a stable body temperature when compared to much smaller creatures.

However, the team from the University of Florida believe that it was the availability of food resources that was the most important factor.

Using a model based on a vertebrate’s energy use, expenditure, mass and eating habits, Dr McNab explained the body size of living and extinct mammals, including baleen whales, an ancient rhinoceros and modern elephants.  He used the example of the larger mass found in some marine mammals which reflect greater resources in their environment.  Developing his argument Dr McNab has stated that the dinosaurs were neither warm or cold-blooded but maintained a stable body temperature somewhere between the warm-blooded mammals and the cold-blooded reptiles of today, thanks to their enormous size.

While Dr McNab said that thermal biology differences are easily seen in small organisms, he suggested dinosaurs were neither cold nor warm blooded but maintained an intermediate temperature between mammals and reptiles, thanks to their size.

According to the American team, herbivorous dinosaurs grew large as their diet of plants was very edible, with later types of dinosaur benefiting from the development of flowering plants (angiosperms) and fruit.  The paper is published in the scientific journal “The Proceedings of the National Academy of Sciences”.

Dr McNab commented:

“Like couch potatoes sitting within easy reach of high calorie foods, the gargantuan size of dinosaurs most likely stems from the abundance of resources available, coupled with low energy expenditures.   Some dinosaurs reached masses that were at least eight times those of the largest, ecologically equivalent terrestrial mammals”.

A Scale Drawing of a Herbivorous Dinosaur – Torosaurus

Picture credit: Everything Dinosaur

The picture shows an approximate size comparison between a person and a Late Cretaceous herbivorous horned dinosaur, a Torosaurus, a close relative of Triceratops.  Could access to lots of plants including fruit have helped these dinosaurs grow so big?

Dr McNab went onto state:

“The factors most responsible for setting the maximal body size of vertebrates are resource quality and quantity, as modified by the mobility of the consumer, and the vertebrate’s rate of energy expenditure”.

This new report is certainly going to raise one or two eyebrows, when extant types of fern and conifer are studied it is clear that they are difficult to digest and lacking in nutrients.  Even angiosperms quickly evolved toxins and other defences to protect themselves from the ravages of large herbivores.  Having to eat particularly difficult to digest food may be a reason in itself why dinosaurs grew so big.  Herbivores needed a huge digestive system to cope with such a diet and the carnivores grew big too, as their prey got gradually bigger and bigger – a sort of plant-eater/meat-eater arms race.

Visit Everything Dinosaur’s website: Everything Dinosaur.