Ancient Feathers found in Amber

According to the recent Proceedings of the Royal Society B a paper has been published on seven prehistoric feathers found encased in amber, the feathers may have once belonged to a dinosaur or an ancient bird.  The feathers have been remarkably well preserved, the amber permitting scientists to see a rare snapshot of evolution in progress.

Prehistoric Feathers

It is not known whether the feathers belonged to a bird or to a dinosaur, however, Dromaeosauridae teeth have been found in the same locality.  Pine resin usually forms lumps on the tree trunk as it slowly flows to the ground, lumps can build up as the resin encounters an obstacle on the trunk, so it is likely the feathers were engulfed in the trees, perhaps indicating that the feathers are more likely to be associated with a bird (avian) rather than a dinosaur (non-avian).

Only one feathered dinosaur known to date is believed to have had an arboreal habit – Microraptor (remains found in the famous Cretaceous deposits of Liaoning, China).  Evidence from the clawed feet and hands indicate that it may have been an effective tree climber.

Amber is a superb medium for fossil preservation.  It is unpalatable and therefore unlikely to get eaten.  Amber is a sticky, often scented resin secreted by certain trees since Jurassic times as protection against disease and to help seal scars in tree bark.  Insects, other organisms and debris can become entombed in the resin and fossilised when it hardens into amber.

This Cretaceous amber was excavated from a quarry in the Charente-Maritime region of Western France.  Along with the Dromaeosauridae teeth, the teeth of another member of the Maniraptora was found nearby. These fossilised teeth have been identified as belonging to a troodontid dinosaur. Both Dromaeosauridae and Troodontidae families have bird-like characteristics and scientists speculate that many genera had feathers.

The finding of evidence of bird-like dinosaurs nearby is a point not overlooked by Vincent Perrichot of the Humboldt University, Berlin; one of the leaders of the project team.

Synchrotron Holotomography

Perrichot and his colleagues used X-ray synchrotron holotomography to image the feathers. This technology utilises a particle accelerator with magnetic and electric fields which allow users to “see” inside many types of materials, including very dense amber.

“Amber fossils are characterised by an exceptional quality of preservation that allows a detailed observation of all tiny structures,” the researchers stated.

When X-rayed, the amber chunk with the seven feathers, now stored at the National Museum of Natural History in Paris, revealed the feathers were lying side by side and the research team claim that they: “very probably originate from a single individual.”

The feathers exhibit what the scientists describe as an: “intermediate and critical stage in the incremental evolution of feathers, which has been predicted by developmental theories but hitherto undocumented by evidence from both the recent and the fossil records.”

Feathers of Modern Birds

Modern birds have a variety of feather forms, each one of which has evolved to do a specific job.  There are the asymmetrical flight feathers, plus symmetrical, fine downy feathers and contour (body) feathers that provide insulation.  It has long been speculated that the first feathers evolved in small, bipedal active predators such as the dromaeosaurs and troodontids to help keep them warm, to act as insulation.  The first feathers, it is thought, consisted of a base shaft with loose barbs coming out of it, sort of like strands of hair secured together at one end.

Those proto-feathers may have been followed evolutionarily by an intermediate stage, represented by the newly identified feathers fossilised in amber.

The seven feathers “have a structure unknown in bird feathers,” on close inspection it can be seen that they are composed of long shafts that fuse progressively to form the central shaft. The seven feathers have a flattened appearance, which the researchers say is a “pre-requisite for using them to fly.”

This type of feather structure has been found in at least one fossil dromaeosaur, the specimen of Sinornithosaurus from the Liaoning deposits of China.  It cannot be certain as to whether these feathers came from a dinosaur or from a bird.  However, these fossil feathers do provide supporting evidence of a recent hypothesis regarding a multi-stage process in the evolution of flight feathers.  This is an example of the fossil record providing evidence to support an existing scientific theory.  The feathers represent part of the evolutionary journey from feathery down for insulation towards the development of asymmetrical flight feathers.

The Fossilised Remains of a Feathered Dinosaur

Sinosauropteryx on display – the first feathered dinosaur described. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The Chinese manufacturer PNSO have specialised in the production of exquisite feathered prehistoric animal models and figures: PNSO Dinosaur Museum Models and Figures.

This discovery is exceptional, the fauna and flora of forest environments do not have a high preservation potential, so little is known about Mesozoic woodland habitats.  This piece of amber permits scientists to see a “snapshot” of evolution in progress from 100 million years ago.

The research team are to report their findings in the Proceedings of the Royal Society, Biological Sciences.  This article has been compiled from a variety of sources including Jennifer Viegas of Discovery News.

Amber can be full of surprises, to read more about fossil finds in amber:

Ancient Harvestman Discovered in Amber.

To Bee or not To Bee – Ancient Bee provides Clue to Orchid Origins.

Evidence of Chemical Warfare from the Mesozoic.

Teeth in Mammals hold the Key to Identification

Mammals have been around for approximately 210 million years, the fossil record indicates that they first appeared in the Late Triassic.  Admittedly, mammals of the Mesozoic were small, many of them were shrew-like creatures, filling the niches not exploited by the dominant reptiles.  It has been speculated that many of them were nocturnal and that they lived inconspicuously in burrows or rock crevices keeping out of the way of the larger terrestrial reptile groups.  Mammal teeth fossils can play a key role in identification and taxonomy.

The Age of Mammals

Following the mass extinction event that ended the Mesozoic era and heralded the start of the Cenozoic, the diversity of reptiles never recovered.  Instead in the animal kingdom the mammals, birds and insects seemed to have rapidly evolved to exploit the new environments and ecological niches opened up by the mass extinction.  In the plant kingdom the angiosperms (flowering plants) continued to go from strength to strength dominating plant life on Earth.  The naming of the Cenozoic is appropriate as translated from the Greek the word means “new life”.

The evolutionary relationships between different types of mammals is unclear, the paucity of the fossil record accounts for this.  Indeed, mammals may have been more common in the Jurassic and Cretaceous than is indicated by the fossil evidence, but the poor preservation potential of these animals limits the amount of fossil specimens likely to be found.

Mammals would have had a limited preservation potential as being small any carcases would soon have been scavenged and the relatively tiny, delicate bones would have been unlikely to survive the fossilisation process.  Inhabiting environments such as deserts, scrubland and woodland would have limited the opportunities for fossilisation even further (these environments are not conducive to fossil forming conditions in normal circumstances).

Mammal Teeth

However, teeth made from enamel, the hardest substance in the body, can survive fossilisation and even though mammal teeth fossils are exceptionally rare they can provide vital information as to the appearance of the entire animal and what it ate.  Many of the extinct early mammal groups are known only from isolated teeth and fragments of jawbones.  Unlike the simple teeth of reptiles (even dinosaurs had relatively simple teeth compared to mammals), mammalian teeth are differentiated by their shape.  The shape of the teeth dictates their function.

Incisors and canines at the front of the mouth are used for obtaining food and holding on to it.  The cheek teeth, towards the back of the jaw are the food processors, grinding up the food as the first part of the digestion process.

To read more about an example of mammalian teeth from the Mesozoic:

Very Ancient Udders! Mesozoic cow discovered in India.

To learn how such specimens are dated (often dated by matrix and sediment data found in-situ with the main specimen):

Dating the Mesozoic Cow! It was the fish and ostracods that did it.

These cheek teeth, the molars and pre-molars have distinctive patterns of cusps, ridges and furrows which in combination with the movement of the jaws allows for efficient cutting and chewing.  These distinctive teeth, their wear patterns and size can provide palaeontologists with a surprising amount of data.  An entire genus could be described from the evidence of a single fossil tooth.

Teeth in Mammals – A Key to Identification

A close-up view of the mouth of the Steppe Mammoth.  Mammalian fossil teeth can be pivotal in identification.  Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The picture (above) shows a close-up view of the teeth of the Eofauna Steppe Mammoth model, a company with a deserved reputation for producing excellent prehistoric mammal models.

To view the Eofauna model range: Eofauna Scientific Research Models.

Teeth Morphology

Teeth morphology can also help scientists distinguish between different types of mammals such as monotremes, marsupials, placental mammals (extant groups) and the now extinct group the multituberculates.  The multituberculates (named after the multiple cusps or tubercles on their molar teeth), were a relatively successful group of Mesozoic and early Cenozoic mammals.

Fossil evidence has been found in Middle Jurassic strata indicating that they evolved around 160 million years ago.  They were probably nocturnal, herbivorous with a burrowing habit, superficially resembling many of the rodents found today.  Most of the fossil evidence has been gathered in the northern hemisphere it is not clear whether these mammals existed in Gondwanaland.

Multituberculates probably gave birth to very small, under-developed young.  This associates them with Marsupials.  This information has been assumed by studying the relatively few fossils of bones from pelvic area.  In many specimens, the pelvic area is quite narrow and this would make the ability to give birth to larger fully formed young unlikely.  This many group went into steep decline towards the end of the Palaeogene, becoming extinct approximately 35 million years ago.

Ancient Arachnid Preserved in Amber

A rare relative of spiders has been discovered preserved in 40 million year old amber.  The little creature was trapped in pine resin and preserved with the resin eventually turning into amber.  This rare specimen identified as a Harvestman (Dicranopalpus ramiger), has been donated to the London Natural History Museum.

The amber, which was from the Baltic area dates from the late Eocene, amber of this age and from the Baltic is fairly common but to find such a rare and complete specimen so well preserved is a very special event.  It seems that around 40 million years ago, a tiny harvestman climbed up a pine trunk, encountered a lump of thick, sticky tree sap and was engulfed.  The whole animal was trapped, a set of events leading to the preservation of this relative of true spiders for scientists to study.

Ancient Harvestman

A Rochester-based fossil collector (Rochester in Kent, England); had purchased a number of amber pieces on an on-line auction website, on receiving the goods, a close examination of the amber revealed a tiny leg hiding in one piece.  He carefully polished it and slowly removed some layers to reveal the complete fossil of this tiny forest inhabitant of the Cenozoic.  Realising he had found something unusual the specimen was sent to the London Natural History museum for expert analysis.

Dr Andrew Ross, Collection Manager of fossil invertebrates and plants at the museum commented:

“When we looked at the amber under the microscope we could see it was a harvestman”.

Harvestmen belong to the arachnid class, the earliest fossil Harvestmen date from the Lower Carboniferous deposits from East Kirkton, Scotland.  A fossil Harvestman from these deposits, an opilonid has been dated to around 320 million years ago, although these creatures may have existed even earlier, perhaps being some of the first creatures to adapt fully to a terrestrial lifestyle.

Today there are around 26 species of Harvestmen in the UK. They may look like spiders with their eight legs but this is only a superficial similarity.  Harvestman have no silk glands, they cannot spin silk, they have not got the ability to defend themselves with a poisonous bite, their only means of defence in most species is to produce a foul smelling chemical to put off a would be attacker.

Different from Spiders

Spiders have a segmented body, with a head, thorax and abdomen clearly divided.  Harvestmen have a fused body with no body segments

“This one is quite a young animal”, explained Dr Ross. “Its body is the size of a pinhead and its legs are about 6 mm long.

“But what is really interesting is that all of its legs are still intact – usually some of the legs will snap off as the creatures try to escape the sticky resin”.

Amber is an important preservation medium, allowing the preservation of small, delicate bodied animals that would not normally be preserved in rock.  This find of a species now extinct helps scientist’s to build up a picture of the ecosystem in those ancient Baltic forests.

For models and replicas of prehistoric animals: Dinosaur and Prehistoric Animal Figures.

“Terrible Claw” – that was not so Terrible

In 1931, the great American fossil hunter Barnum Brown discovered the bones of a small, agile predatory dinosaur in Wyoming (Western USA).  The animal was named Daptosaurus, it means “active lizard”.  Unfortunately, despite being aware that this was a new genus of dinosaur, Barnum Brown never actually got round to describing this new dinosaur, and as a result Daptosaurus was not recognised by the wider scientific community.

Deinonychus – A New Interpretation

John Ostrom, another American palaeontologist, uncovered more fossilised bones of Daptosaurus in 1964 and he went onto name and describe the animal as Deinonychus in 1969, on year after Barnum Brown had sadly passed away.  So far, something approaching a dozen specimens have been found, including the remains of Deinonychus individuals next to a Tenontosaurus (a large hypsilophodontid herbivore), a rare example of predator and prey being found together.

The work of John Ostrom and other researchers led many scientists to see dinosaurs in a different light.  Instead of being depicted as slow, lethargic cold-blooded reptiles many began to be interpreted as active, agile and bird-like.

Deinonychus remains have been found in Early Cretaceous strata of Montana, Oklahoma and Wyoming.  The animal grew to a length of approximately 3 metres and might have weighed as much as 80 kilogrammes.  The head was 2.5 metres off the ground.   From the group of Deinonychus fossils (and recent trackway evidence), it has been suggested that this animal, a member of the Dromaeosauridae, lived and hunted in packs.

To read more about recent finds of dromaeosaur trackways: Evidence of Pack Behaviour in “Raptors” unearthed in China.

More dromaeosaur trace fossil news: Two-toed footprints found in Korea – Evidence of Dromaeosaurs in Korea.

The second toe of the four on the hind foot did not touch the ground.  Instead it was held aloft as it had the large sickle-shaped claw on the end.  Scientists like Ostrom speculated that this was probably the primary weapon used by this fierce little hunter.  The claw could have been swung forward and used to slash its victims.  However, recent studies by a team from the University of Manchester and other groups has cast some doubt over this hypothesis.  Although the point of the claw was relatively sharp the curved surface of the claw was not so sharp.

The force needed to slash away at the tough hide of a dinosaur would have been immense.  It now seems that this claw may have served more as a grappling hook, allowing a pack of Deinonychus to mob a larger dinosaur, jumping on it using their claws to get a purchase and to help bring the animal down.

An Illustration of Deinonychus (D. antirrhopus)

Picture credit: Everything Dinosaur

Close analysis of the jaws of dromaeosaurs including Deinonychus indicate that they were very strong.  Large muscles positioned towards the rear of the skull indicates that they could be opened very wide (wider than the 70 degrees permitted by the jaws of a lion).  Perhaps the jaws could have opened wide enough to bite down onto the windpipe and suffocate large prey animals – a form of predation favoured by many big cats today.

The Beasts of the Mesozoic range of articulated dinosaur models features several dromaeosaurid dinosaurs.  To view this popular range of collectable dinosaur figures: Beasts of the Mesozoic Dinosaur Figures.