Fossil Finds

[rogue06]

The discovery of yet another strange ancient extinct crocodile has been announced. This time it's an enormous prehistoric crocodile with a shield-like bony plate on its skull called "Shieldcroc," which lived between 93 and 99 mya (Late Cretaceous).

The specimen is represented by a partial skull excavated from continental freshwater deposits of what would later become Morocco. The lead researcher, Casey Holliday, a professor of anatomical sciences at the University of Missouri, says that it "probably had a head size of two meters (6½')" long.

"Shieldcroc" appearantly had a very long, flat face, a rounded nose with small teeth and slender, relatively delicate, duck-like jaws that weren't capable of wrestling with large prey. Still with its giant size it was no push-over.

Inferences based upon the size of the braincase indicates that "Shieldcroc" grew up to 18 meters (59') long -- a size that Holliday called "pretty ridiculous." He thinks the proportions aren't correct and that it was probably closer to being around 9 to 11 meters (29½-36') long.

The researchers said it is thought that modern horned crocs will raise the back of their heads to show off their horns during courtship and territorial disputes and feel that the shield on this ancient species may have served a similar purpose.

The rivers that "Shieldcroc" inhabited also held lungfish and coelacanths (the modern ones live in salt water) that reached up to 4 meters (13') in length. The researchers think that they may have served as prey for "Shieldcroc."

Analysis of "Shieldcroc's" skull reveals that it was a member of a group called the eusuchians ("true crocodiles"), a lineage that includes modern alligators and crocodiles. It is the first confirmed discovery of an eusuchian in Africa. The oldest member of this group, Hylaeochampsa, was discovered on the Isle of Wight in the British Channel and is around 125 to 130 myo (Early Cretaceous).

In any case, the researchers think "Shieldcroc" could possibly be the last common ancestor of modern day crocodiles and alligators. This would mean that modern crocodiles may have first evolved near the Mediterranean Sea.

shieldcroc-zoom.jpg

Further Reading:

Ancient Monster Croc Sported Shield on Skull

'SHIELDCROC' MAY BE FATHER OF ALL CROCODILES

‘Shieldcroc’ could be father of all crocodiles

[rogue06]

Ever since Charles Walcott discovered the Burgess Shale in the Canadian Rockies of British Columbia back in 1909 researchers have uncovered the remains of thousands of fossilized organisms in the Cambrian period rocks there.

Now for the first time a trackway of fossilized footprints which captured the movement of a large seafloor-dwelling arthropod with 33 pairs of legs that lived 500 mya has been uncovered. Actually, it appears that these are the first tracks of any sort discovered in the Burgess.

In fact five separate trails were discovered in two locations in the oldest part (Kicking Horse Shale Member) of the Burgess Shale Formation. The longest trackway stretched approximately 3 meters (nearly 10') with the footprints set over 10cm (4") apart, suggesting a good-sized creature with a wide stance.

Due to the size of the tracks and the number of legs needed to make them the animal likely responsible for laying down the tracks was an ancient beetle-like creature called Tegopelte gigas which was a soft-shelled trilobite that grew up to 30cm (just under 1') in length and 14cm (5½") wide and is known from just two specimens that were excavated in the 1980s.

As the head of the research team, Nicholas J. Minter of the University of Saskatchewan's Department of Geological Sciences, said, "Short of finding an animal at the end of its trackway, it's really very rare to be able to identify the producer so confidently."

Tegopelte was more than twice the size of all other benthic arthropods known from this locality and only an organism uncovered in China even approaching its size.

It was a carnivore though whether predator, scavenger or even both is not known. Whatever the case it was capable of rapidly skimming across the seafloor with only a few of its many legs touching the ground at any one time. Considering its size it probably didn't use its speed to escape predators.

The first of the tracks was discovered in 2000 but couldn't be safely removed without assistance of a helicopter which was done in 2008.

Now that they know where to look another expedition is being organized in an attempt to find more tracks and maybe even some fossilized remains of Tegopelte next summer.

Tegopelte.jpgTegopelte2.jpg
Reconstruction of Tegopelte along with actual fossils of it

Tegopelte1.jpg
Actual trackways

Further Reading:

Skimming the surface with Burgess Shale arthropod locomotion Abstract

Half-Billion-Year-Old Predator Tracked: Multi-Legged Creature Ruled the Seas

Ancient 66-legged animal made tracks in the Burgess Shale

50-Legged Creature May Have Been Top Predator of Ancient Seafloor

[rogue06]

While examining a chunk of 44–49 myo (Eocene) succinite, or amber from the Baltic region, which contained a dysderidae spider, researchers spotted what they call the "smallest arthropod fossil ever" using X-ray computed tomography (CT) scanning techniques as a complete body fossil.

Specifically, a mite 176 micrometers (.176mm or 0.0069") long which is barely detectable to the human eye was located on the spider's head.

But by using CT scanning the researchers produced incredible 3-D images that allowed them to "digitally dissect" the mite and study its anatomy in detail. The researchers note that the mite was “preserved with lifelike fidelity."

The prehistoric mite was a member of a group known as Astigmata which were unknown in the fossil record until now. The team leader, Jason A. Dunlop of the Leibniz Institute for Research on Evolution and Biodiversity, Humboldt University in Berlin said that the astigmata group "might go back 270 million years and mites as a whole go back 410 million years."

Further the hitchhiking mite is the earliest example of phoretic behavior (symbiotic relationship where one organism transports another organism of a different species) yet discovered. Such behavior is common in several different groups today.

Interestingly, the modern-day descendants of these mites don't usually travel on spiders but tend to prefer beetles.

SpiderMite1.jpg SpiderMite2.jpg
SpiderMite3.jpg

Further Reading:

A minute fossil phoretic mite recovered by phase-contrast X-ray computed tomography Abstract

Hi-Tech Scans Catch Prehistoric Mite Hitching Ride On Spider

Amber-Encased Mite Found Clinging to Fossil Spider includes video

MITE FOSSILIZED WHILE SUCKING ON SPIDER'S HEAD

'Smallest fossil' scanned by University of Manchester

Ancient mite caught hitching ride on a spider

[rogue06]

Researchers have announced the discovery of the remains of a massive breeding colony of Mesozoic birds, preserved in limestone deposits at the Oarda de Jos (Od) site in the Hatzeg Basin of the Sebes area of Transylvania, Romania which dates from approximately 100 mya (Late Cretaceous). It represents the first fossil evidence for a breeding colony of birds from this era.

The site includes the fossilized bones of adult birds and chicks, numerous intact eggs and huge clusters of eggshell fragments demonstrating that prehistoric birds dwelled in nesting colonies not unlike ducks and flamingos today.

The birds themselves belonged to the group known as enantiornithines, the most abundant and diverse group of birds of the Mesozoic, almost all of which bore clawed wings and toothed beaks but were in all other respects like modern birds and who went extinct at the same time as did the dinosaurs.

According to co-author Darren Naish, a vertebrate paleontologist at the University of Southampton the birds "would have looked peculiar to modern eyes." In addition to their toothiness, they had "a heavier looking tail." Apparently enantiornithines didn't have tail feathers that formed a lift-generating fan like those seen in modern birds.

The researchers think the nest and the birds were wiped out during an ancient flash flood when a nearby river rose a couple feet taking the colony by surprise.

According to Naish, "The water sweeping across the colony picked up broken eggshell, any remaining eggs and birds, and carried them a few meters across to a shallow depression, perhaps present on the other side of the colony."

While the Sebes area is known for its abundance of fossils from dinosaurs, crocodiles and pterosaurs only the remains of the enantiornithine birds and their eggs have been found at this site.

The lead researcher, Gareth Dyke of the University of Southampton and University College Dublin, said that this discovery is important because not only is it the first evidence that ancient birds nested along the water like modern ones do but also because "This is the first evidence for actually really well-preserved, complete eggs that actually can tell us about the biology of these animals."

According to Dyke, until now "only a handful of undisputed, isolated Cretaceous eggs are known.”

The researchers hope that this discovery will help them determine why these birds died off while others lived on to the modern day. Dyke noted that the egg morphology will probably be able to tell us something about their reproductive biology, and feel that might provide clues for why they went extinct.

enantiornithine.jpg
Not sure if this is from the new discovery or
just an example of enantiornithine fossil

Further Reading:

A DROWNED MESOZOIC BIRD BREEDING COLONY Abstract

Flash Flood Drowned Dino-Era Bird Colony

Silence of the enantiornithines: Fossils show flood wiped out colony of dinosaur-era birds

DINO-ERA DISASTER: MULTIPLE DROWNED TOOTHY BIRDS

[rogue06]

A 3 to 4 myo (Pliocene) small fossilized section of rib from an ancient whale that was probably an ancestor of either the modern blue or humpback whale was excavated from the Yorktown Formation within the PCS Phosphate Mine (formerly Lee Creek Mine) near Aurora, in eastern North Carolina.

By itself this hardly is newsworthy but the fossil whale rib exhibits three tooth marks indicating that the creature it came from had been severely bitten by a strong-jawed animal.

The research team, led by Robert J. Kallal Department of Paleontology, Calvert Marine Museum, Maryland, think that the 6cm (2.36") spacing between tooth marks means that the attacker was a large shark of some type, possibly the extinct Carcharocles megalodon -- a shark that grew to 16 meters (15½') in length.

The size and spacing of the bite marks suggest that this attacker was relatively small being somewhere between 4 and 8 meters (13-26') in length.

A CT scan of the bone provided evidence that the bone was in the process of healing when the whale died roughly six weeks later since the wounds were covered with "woven bone" which forms over traumatic damage but doesn't have the same density of normal bone though over time it compacts.

It isn't known why the whale died several weeks after the attack but the lesions on the bone showed signs of inflammation which was almost certainly caused by infection secondary to the trauma.

In any case the whale wasn't killed when the shark attacked it but managed to survive the event, the indications of which are something that is considered rare in the fossil record. But the discovery has caused the researchers to urge other paleontologists to re-examine any lesions they discover on any recovered whale bones to see if they might indicate similar encounters.

whaleribbites.jpg

Further Reading:

Bone reactions on a pliocene cetacean rib indicate short-term survival of predation event Abstract

Ancient Shark Attack Preserved In Fossil Whale Bone

4 million year old shark attack recorded in whale bone

[rogue06]

A 3 to 4 myo (Pliocene) small fossilized section of rib from an ancient whale that was probably an ancestor of either the modern blue or humpback whale was excavated from the Yorktown Formation within the PCS Phosphate Mine (formerly Lee Creek Mine) near Aurora, in eastern North Carolina.

By itself this hardly is newsworthy but the fossil whale rib exhibits three tooth marks indicating that the creature it came from had been severely bitten by a strong-jawed animal.

The research team, led by Robert J. Kallal Department of Paleontology, Calvert Marine Museum, Maryland, think that the 6cm (2.36") spacing between tooth marks means that the attacker was a large shark of some type, possibly the extinct Carcharocles megalodon -- a shark that grew to 16 meters (52½') in length.

The size and spacing of the bite marks suggest that this attacker was relatively small being somewhere between 4 and 8 meters (13-26') in length.

A CT scan of the bone provided evidence that the bone was in the process of healing when the whale died roughly six weeks later since the wounds were covered with "woven bone" which forms over traumatic damage but doesn't have the same density of normal bone though over time it compacts.

It isn't known why the whale died several weeks after the attack but the lesions on the bone showed signs of inflammation which was almost certainly caused by infection secondary to the trauma.

In any case the whale wasn't killed when the shark attacked it but managed to survive the event, the indications of which are something that is considered rare in the fossil record. But the discovery has caused the researchers to urge other paleontologists to re-examine any lesions they discover on any recovered whale bones to see if they might indicate similar encounters.

whaleribbites.jpg

Further Reading:

Bone reactions on a pliocene cetacean rib indicate short-term survival of predation event Abstract

Ancient Shark Attack Preserved In Fossil Whale Bone

4 million year old shark attack recorded in whale bone

Corrected the part where I said 16 meters equals 15½'

[moreta]

I didn't notice.



Oh yeah...Hey Rogue!!! 15 1/2 ft is a little short for 16m, isn't it? !!!1!!11!1

[rogue06]

Mentioning this primarily because of a few recent posts on fossil whales (here, here and here), but apparently a collection of at least 80 whale fossils have been discovered at a site known as "Whale Hill" to the locals of Bahia Inglesa (English Beach) a beach town 6km (3¾ miles) south of the port city of Caldera, along the incredibly arid Atacama desert in northern Chile.

That places the location of this ancient whale graveyard, which includes previously unknown species which haven't been formally identified yet, roughly 869km (540 miles) north of the capital of Chile, Santiago.

Many of the fossils are very complete and well preserved and don't seem to have been scavenged. They include what is probably a family group that appears to be a mother, father and baby whale, which all date back to 7 mya (Late Miocene).

The articles don't mention what the researchers think caused this accumulation of prehistoric whales. Whether it was a recurring environmental disaster, an estuary with oxygen depleted or otherwise toxic waters or something else was not stated.

It wasn't just ancient whales but also the remains of sharks and other marine mammals such as dolphins and seals.

Further Reading:

Scientists unearth huge fossil bed with complete whale skeletons along Chile’s coast

Whale cemetery discovered in Chile includes 1 min video

[rogue06]

A new examination of the fossilized remains of an unusual long-snouted mosasaur excavated in 1953 from the Santonian (Upper Cretaceous) part of the Smoky Hill Chalk Member of the Niobrara Formation a few miles northwest of the town of Wakeeney in western Kansas has revealed scales and skin impressions allowing researchers a glimpse into how these extinct marine reptiles moved.

When the roughly 85 myo specimen, which consists of a complete skull and articulated anterior half of a skeleton, was originally discovered it was noted that this material was present but most was removed during its preparation and the soft-tissue structures that were still left remained unstudied until now.

The new findings revealed that the scales on this species of mosasaur were less than a tenth of an inch (2.7 × 2.0mm) across meaning that its skin would have felt relatively smooth and not scaly.

The fossilized skin samples also display imprints of the protein fibers that made up its skin. In that these fibers often crisscrossed indicate that skin was pulled taut around the front half of its body meaning that at least the front portion of the mosasaur's body was stiff.

Previously, it had been thought that mosasaurs had swam in a snake-like manner moving their vertebrae from side to side and using most of its body to make undulating waves. The taut skin would restrict such movement and suggest that they would have moved much more like like sharks and whales.

IOW, if the front half of the body was relatively rigid then it had to depend on the rear of its body and tail for propulsion as it swam.

"They [the mosasaurs] have, for 200 years, been reconstructed as these serpentine creatures," lead researcher Johan Lindgren from Sweden's Lund University Department of Earth and Ecosystem Sciences said. "An emergence of evidence, including the stuff we found, indicates that they underwent the same kind of evolution as whales, and they became streamlined."


In a seperate discovery some exceptionally well preserved vertebrae have been found in Late Cretaceous rock up near Morden in southern Manitoba where a Xiphactinus was excavated from last year.

This wouldn't be newsworthy except that the fossils were found in sedimentary rock that's part of the Boyne Member meaning that the new discovery suggests that mosasaurs were capable of inhabiting deep water environments. Previous discoveries have been in deposits laid down in relatively shallow seas.

mosasaur1.jpg mosasaur2.jpg

Further Reading:

Three-Dimensionally Preserved Integument Reveals Hydrodynamic Adaptations in the Extinct Marine Lizard Ectenosaurus (Reptilia, Mosasauridae) Abstract & Paper

Pristine Reptile Fossil Holds New Information About Aquatic Adaptations

Fossilized skin shows predator's sharklike moves

Fossilized tissue wows researchers


CFDC Mosasaur Discovery Changing Conceptions Info on Canadian discovery

[rogue06]

Researchers have announced the discovery of a 70 to 80 myo (Late Cretaceous) fossilized dinosaur nest in the Central Asia's Gobi Desert at the Djadochta Formation, Tugrikinshire, Mongolia. The nest was round and bowl-shaped which measured approximately 70cm (27½") diameter and contained the remains of 15 baby dinosaurs, 10 of which are complete fossil sets.

While numerous fossil eggs have been associated with other dinosaurs, such as the small carnivorous theropod Oviraptor or some duck-billed herbivores called hadrosaurs, its much rarer to find nests containing multiple juveniles.

The young dinosaurs were small herbivorous ancestors of Triceratops known as Protoceratops andrewsi. This is the first Protoceratops nest ever found. Nests which had earlier been thought to have been theirs turned out to have belonged to other types of dinosaurs.

The remains measured between 10 to 15cm (4-6") in length. That they were juveniles is confirmed by the short snouts with proportionately large eyes along with the small size of their frills.

The dinosaur's size along with the degree of skeletal development, and the lack of any eggshell material inside the nest all suggest that they weren't newborns but had been living in the nest for awhile though probably not more than a year.

The researchers, headed by David E. Fastovsky, chair of the Department of Geosciences at the University of Rhode Island, think this may indicate these sheep-sized dinosaurs with their distinctive neck frill at the base of the neck, may have provided care for their young and continued to do so through the babies' juvenile development.

Fastovsky declared that, "It's quite striking that there are 15 juvenile Protoceratops here — that seems like a lot to care for. But they were living in a harsh environment, so perhaps mortality rates were high." He added that "Large clutches may have been a way of ensuring survival of the animals in that setting — even if there was extensive parental care."

Still because no adult Protoceratops was found in association with the young juveniles it could also mean that instead of an adult continuing to care for them while they remained in the nest it might be that the adults had abandoned the nest and the baby Protoceratops remained together in the nest area

Finally, Fastovsky and his team think the discovery serves to continues to corroborate the conclusion that "Protoceratops lived (and died) in the sandy aeolian dune fields of the central Asian craton" in that the nest and its inhabitants were “rapidly overwhelmed and entombed” by sand.

Fastovsky said, "The evidence suggests they may have been overrun by migrating dunes during a sandstorm."

Protoceratops-human_size.JPG
protoceratops-nest2.jpgprotoceratops-nest1.jpg

Further Reading:

A Nest of Protoceratops andrewsi (Dinosauria, Ornithischia) Abstract

15 Infant Dinosaurs Discovered Crowded in Nest

Nest filled with baby dinosaurs found in Mongolia

Nest Full of Baby Dinosaurs Discovered

At Last, a True Protoceratops Nest

Baby dinosaurs caught having a lie-in in the Gobi desert

[rogue06]

A new genus of basal sauropodomorph dinosaur that appears to be missing several typical characteristics of sauropodomorphs has been unearthed from a mudstone block in the Alemoa Member of the Santa Maria Formation (Rosário do Sul Group) in the Janner or Várzea do Agudo locality in the middle of the southern most Brazilian state of Rio Grande do Sul that dates from 228 to 230 mya (Late Triassic).

The dinosaur is known from a single specimen that included the majority of the skull, mandible along with 28 teeth as well as elements of the shoulder girdle and most of the forelimbs, an ilium and most of the hindlimbs, and numerous vertebrae and ribs.

The specimen has informally been named Pampadromaeus barberenai. The first part comes from "pampa," meaning "plain" in the local indigenous language in reference to the current terrain along with "dromeus" which is the Greek word for "runner." The species name honors Mario Costa Barberena, a paleontologist who has done considerable work in the region.

Pampadromaeus was a small bipedal omnivore a little over a meter long who's lower leg was much longer than the thighbone which indicates it was a good runner. The short forelimbs suggest that it was an obligate biped and didn't switch between walking on two legs and all fours as seen in later sauropodomorphs.

It had different sorts of teeth with leaf-shaped ones associated with plant-eating in the front and short recurved ones associated with meat-eating in the rear.

Moreover Pampadromaeus appears to displays a combination of basal and derived traits. Some of new traits are similar to those found in theropods such as a subnarial gap formed by a downward pointing premaxilla and a depression where theropods possess a membrane covered opening known as the fenestra promaxillaris. A few of the basal traits are its short femur, large skull and the possession of just two sacral vertebrae.

While four different cladistic analyses show that Pampadromaeus fits consistently on the sauropodomorph stem, the lack of several typical features of sauropodomorphs along with some neotheropod traits demonstrate that figuring exactly where it fits in relation to sauropodomorphs is difficult to ascertain.

In any case, Pampadromaeus appears to be more closely related to the early sauropodomorphs than to the forerunners of theropod dinosaurs. In fact, several of the analyses in the study position Pampadromaeus just outside the sauropodomorph group, implying that it represents a “stem” lineage from which the true sauropodomorphs evolved.

Still the researchers led by Sergio F. Cabreira of Luterana University's Museum of Natural Sciences in Canoas, Rio Grande do Sul, Brazil, emphasized that this position wasn't strongly supported, illustrating the difficulty of determining the affinities of such early forms.

Pampadromaeus1.jpg Pampadromaeus2.jpg

Further Reading:

New stem-sauropodomorph (Dinosauria, Saurischia) from the Triassic of Brazil Abstract & Paper

Pampadromaeus: Brazil’s Triassic Plains Runner

Pampadromaeus

[rogue06]

Researchers have discovered an extremely well-preserved and nearly complete undistorted skull of an extinct tetrapod from the Colonia Orozco locality in the Buena Vista Formation's fluvio-aeolian sandstone and conglomerate deposits of the Norte Basin in northeastern Uruguay that dates from the Late Permian or Early Triassic (around 252 mya).

The skull, which is missing most of the snout, represents a previously unknown extinct genus and species of temnospondyl, a widely varied group of amphibians that flourished worldwide up into the Cretaceous. The researchers named the specimen Arachana nigra.

Arachana appears to have had a transitional morphology sharing traits from both rhinesuchids and lydekkerinids. This means that it was a transitional form between early basal rhinesuchid and the later, more advanced lydekkerinid stereospondyls.

Some of the basal characteristics include the basic shape and large size of the skull with the eye cavities placed slightly behind the skull's roof mid-length and a smoothly convex cheek contour. Arachana also had a small basioccipital bone at the back of the skull which is found in rhinesuchids and other basal temnospondyls.

Among some of the more advanced features commonly found in the Lydekkerinidae, but absent in almost all rhinesuchids, found in Arachana include the shallowness of the otic notch on the back of the skull; the post temporal fenestra (the holes in the back of the skull) are large and rounded; the occipital condyles (undersurface facets of the occipital bone in vertebrates) are well-separated from each other; the teeth on the palatine bone are reduced and the presence of an interorbital depression.

This combination of primitive and derived features found in Arachana is found in nearly all parts of the Buena Vista fauna and place it as part of an entire transitional fauna that existed around the Permo-Triassic boundary.

While the researchers can't yet determine whether Arachana lived before or after the Permian-Triassic extinction event (informally known as the Great Dying because roughly 95% of marine species and 70% of terrestrial spieces going extinct), its transitional position suggests that the speciation rate of some temnospondyls were increasing rather than diminishing after the Permian-Triassic event.



Further Reading:

A rhinesuchid-like temnospondyl from the Permo-Triassic of Uruguay Abstract*

A Newly Described, Possible Transitional Stereospondyl

Wikipedia: Archana



*Occasionally the link glitches allowing quick access to the entire paper

[rogue06]

Been waiting on this ever since I heard about the presentation concerning it at the annual Society of Vertebrate Paleontology meeting in Las Vegas at the start of the month.

A recent discovery of a unique specimen of the pigeon-sized four-winged theropod dinosaur Microraptor gui excavated from the Jehol Group in northeastern China and thought to be between 120 and 131 myo (Early Cretaceous) is causing quite a commotion.

Apparently it contains the nearly complete fossilized skeleton of an adult enantiornithine bird preserved where the stomach of a dinosaur would have been thereby providing the first direct evidence for something that has been long suspected but were previously unable to verify -- namely that some dinosaurs hunted and ate their feathered relatives.

The Microraptor probably weighed somewhere around a half kilogram (1lb.) whereas the bird likely weighed between 60 to 70gms (2-2½oz).

Being that the remains of the bird are still articulated this indicates that it was doubtful that it had been scavenged but was rather captured and consumed by the dinosaur. Also there was no indication that the bird had been chewed so this and the fact that it was still intact lead the researchers to think that the bird was swallowed whole as live prey.

Since the bird's remains were found facing down towards Microraptor’s hips suggest that the dinosaur likely swallowed it head-first, the same orientation normally used by many modern birds of prey.

So not quite a Cretaceous "turducken," but close.

As the researchers note, such direct evidence concerning what a long extinct animal ate is extremely rare. Usually the evidence comes from the characteristics of the teeth, tooth marks on fossil bones or fossilized feces (coprolites) but this discovery provides direct evidence.

Still, this sort of discovery isn't unprecedented. As the researchers point out, "The first feathered dinosaur Sinosauropteryx often preserves the remains of mammals and lizards in the stomach cavity, a specimen of the mammal Repenomamus preserves the remains of a baby Psittacosaurus dinosaur, the basal ornithurine bird Yanornis preserves fish remains in the stomach of one specimen, and a specimen of the giant compsognathid Sinocalliopteryx was reported to have an incomplete dromaeosaurid leg preserved inside its abdominal cavity."

And there's the 299 myo fish-within-an-amphibian-within-a-shark (along with another amphibian just for good measure).

But even more importantly this new discovery may provide some supporting evidence for the notion that Microraptor may have been a tree dweller. Since all of the Jehol enantiornithines were distinctly arboreal with legs and feet obviously adapted to perching in trees rather than running or swimming. According to the researchers if its prey lived among the branches then this implies that Microraptor hunted in the trees.

And considering that its prey was an adult, rather than a chick, Microraptor had to be a fairly agile predator. “[The fossil] lends further support to interpretations that Microraptor gui was spending a substantial amount of time in the trees,” noted the study's leader, Jingmai O’Connor of the Chinese Academy of Sciences' Institute of Vertebrate Paleontology and Paleoanthropology.

The researchers think that Microraptor's four wings may have allowed it to glide between trees to hunt prey there and this discovery provides further support for the arboreality of basal dromaeosaurids.

Still, we shouldn't jump to conclusions here. Just because enantiornithines are aboreal doesn't exclude the possibility that they also didn't also periodically go down to the ground since most arboreal birds do so today. Further, another microraptor fossil was found with a mammal bone in its abdomen, so we can't say that this bird represents the Microraptor's usual meal.

In any case, this is a pretty spectacular find, and does offer a few new insights into this unusual dinosaur's lifestyle.

Microraptor_fossil2.jpg Microraptor_fossil.jpg

Further Reading:

Additional specimen of Microraptor provides unique evidence of dinosaurs preying on birds Abstract

First evidence that dinosaurs ate birds

Dinosaur's Meal Preference: Evidence Shows Dinos Ate Birds

Fossil flying dino enjoyed tasty bird snack as last meal

Four-winged dinosaur fossilized after swallowing a bird

Microraptor – the four-winged dinosaur that ate birds

First evidence found that dinosaurs ate birds

[rogue06]

The largest collection of feathers dating from North America's Mesozoic era have been found in the Ingersoll Shale portion of the Eutaw Formation in eastern Alabama and are from approximately 84 mya (Late Cretaceous).

Fourteen feathers were excavated from the mudstone of what once was an ancient estuary or tidal channel that was along the coast of prehistoric Alabama. They range in size and morphology though they all appear to be contour feathers with the majority coming from the outer layer of plumage.

The largest specimen, at 16.5cm (6½"), was probably a tail feather and based on the known taxa in the area probably from a dromaeosaurid dinosaur or from a hesperornithid or even the extinct flightless bird Hesperornis. Another is thought to have come from a wing and several of the smaller ones might have come from an assortment of shore birds like Ichthyornis and Halimornis.

It is extremely difficult to determine exactly which feather goes to what creature considering that many of the habitat's likely contestants are only known from partial remains. Some could even originate from some currently undiscovered candidate.

Several of the feathers were likely damaged before being buried and as a result are incomplete, but some are extremely well preserved and retain microstructure composed of carbonized rod-shaped bodies 1 micrometer ( 0.001 mm or 0.000039") in length. They were able to preserve their three-dimensional structure thanks to pyrite replacing parts of the feathers.

While in some ways similar to bacteria the alignment of these microscopic bodies along the axis of feather structures signifies that they are probably fossilized melansomes -- organelle containing melanin responsible for color production during life.

As recent research has shown, melansome structure tends to correspond to color and when they are sufficiently preserved in fossil feathers they can be compared to their counterparts in modern birds to reconstruct colors.

According to the researchers headed by Terrell K. Knight, a paleontologist with Auburn University's Department of Geology and Geography, these feathers weren't patterened but were monochromatic "ranging from gray and brownish gray to black.”

alabama-feathers.jpg

Further Reading:

FEATHERS OF THE INGERSOLL SHALE, EUTAW FORMATION (UPPER CRETACEOUS), EASTERN ALABAMA: THE LARGEST COLLECTION OF FEATHERS FROM NORTH AMERICAN MESOZOIC ROCKS Abstract

Alabama’s Wealth of Fossil Dinosaur Feathers

[rogue06]

Researchers have announced the discovery of the largest osteoderm ever found in the Anembalemba Member of the Maevarano Formation in the Mahajanga Province in the northwestern part of the island nation of Madagascar that are around 65 to 70 myo (Late Cretaceous).

Osteoderms are literally bony deposits in the skin that form scales, plates or other structures in the dermal layers. They can be found in many animals like crocodiles and lizards and in various groups of dinosaurs, most notably ankylosaurs and stegosaurs. They're even found in a few mammals like armadillos.

This particular specimen came from a type of sauropod dinosaur known as titanosaurs, specifically a Rapetosaurus krausei, which reached up to 15 meters (over 49') in length. Titanosaurs are the only known group of sauropods that hadn't gone extinct by the Late Cretaceous.

The osteoderm, found near the hips of an adult Rapetosaurus, is shaped like an American football sliced lengthwise, measuring 57.2cm × 26.7cm × 19.2cm (22½" x 10½" x 7½") in maximum dimensions and has an estimated volume of 9.63 liters (2.54 gallons).

Normally osteoderms act as armor and serve to strengthen a creature's hide against attacks, but since Rapetosaurus appears to have had only a few osteoderms in its skin this means that they were less likely to serve as protection and probably had a different purpose.

After being analyzed under CT-scanning the researchers found that the inside of the osteoderm was mostly hollow and that the internal cavity was equivalent to more than half its total volume. Being largely hollow, relatively thin-walled bone is further indication that these structures weren't serving to protect the sauropod from attack.

Further, the thickness of the outer layer varied around the internal cavity, and the microscopic bone structure inside the osteoderm displayed indications that bone was actually being resorbed by the body.

The researchers, headed by Kristina Curry Rogers of the Biology and Geology Departments at Macalester College in St. Paul, Minnesota, think that hollow bones might have served as internal mineral reservoirs and that the adult Rapetosaurus probably drew upon the calcium and phosphorous in them in order to maintain their huge skeletons and to lay large egg clutches.

Female titanosaurs are known to have laid many volleyball-sized eggs much in the same manner that today's crocodiles and alligators lay dozens of eggs and absorb minerals from their bones. The extra calcium would be useful in allowing the eggs to produce a hard shell.

Sediments around the fossils indicate that Rapetosaurus inhabited a hot, semi-arid environment subject to periodic droughts that was poor in such minerals so this would have proved very useful and helped them survive in such a climate.

Another smaller osteoderm was discovered near the tail of a juvenile Rapetosaurus at the same location. Examination of it showed that unlike the specimen from the adult it was solid and indicated little if any evidence of bone remodelling and therefore weren't yet used to store minerals. The differences between the two should help us determine how osteoderms changed over the span of a lifetime.

osteoderm-1.jpg

Further Reading:

Sauropod dinosaur osteoderms from the Late Cretaceous of Madagascar Abstract & Paper pdf

'Skin Bones' Helped Large Dinosaurs Survive, New Study Says

Madagascar Dinosaur Bone Is Most Massive Osteoderm Ever Found

Osteoderms storing minerals helped huge dinosaurs survive

Inside Sauropod Armor

Bone minerals helped dinos in tough times

Bizarre Madagascar Fossil Find Sheds Light on Long-Necked Dinosaurs