Saturday, December 10, 2016

Dinosaur Tail Trapped in Amber !!!


 Another amazing find in Burmese Amber !!! Read New York Times Article Below:

See my post about Burmese Amber in August listing

http://www.nytimes.com/2016/12/08/science/dinosaur-feathers-amber.html



A 99-million-year-old piece of amber with a feathered dinosaur tail trapped inside.

Credit

Ryan McKellar/Royal Saskatchewan Museum


While most paleontologists dig up prehistoric bones from the ground, Lida Xing hunts for fossils in the amber markets of Myanmar. In 2015, he made a remarkable find: Trapped in what looked like golden glass was the feathered tail of a dinosaur.

Along with the primitive plumage, the 99-million-year-old amber also preserved soft tissue and eight complete vertebrae. The tail bones indicated that the specimen belonged to a dinosaur that was not a prehistoric bird and also provided researchers with insight into the evolution of feathers.

“This is the first time that skeletal material from a dinosaur has been found in amber,” Dr. Xing, who is a paleontologist at China University of Geosciences in Beijing, said in an email. He and his colleagues published their findings Thursday in the journal Current Biology.

After performing a CT scan and microscopic analysis, Dr. Xing and his colleagues realized that the feathers did not belong to a bird because the specimen’s tail vertebrae were not fused into a rod, as they are in modern birds. The feathers most likely belonged to a baby nonavian theropod, meaning it looked more similar to a velociraptor or Tyrannosaurus rex than to a modern bird. That said, it was probably only about the size of a sparrow.

Photo



An artist’s rendering of a small coelurosaur, which the researchers think may be the type of dinosaur whose tail became trapped in amber.

Credit

Chung-tat Cheung



After death, the tiny dinosaur’s body was most likely covered in tree resin. The resin is produced as a defense mechanism against insect infestations. When it dries it becomes a plasticlike substance that can survive for millions of years.

“Once the resin leaks out on the side of the tree it’s like a big sticky trap waiting for anything to fall into it,” said Ryan McKellar, a paleontologist at the Royal Saskatchewan Museum in Canada and an author of the study. “Then once the next resin falls on top of the existing one, it seals it in.”

After Dr. Xing found the amber, he sent it to Dr. McKellar, an amber expert, to further investigate the specimen.

“When it hit my desk, I was blown away,” Dr. McKellar said. “It’s one of those things where you’re like ‘Wow, it’s the closest you’ll ever get to holding a fleshed-out dinosaur in your hands.”

Using a high-powered microscope, Dr. McKellar recorded images of the amber. He found that the underside of the feathers was white and the top was chestnut brown. But it was not the color that fascinated him the most.

“I was seriously puzzled by the feather structure we’re seeing in this sample,” he said.

Most modern bird feathers have a central shaft called a rachis; think of the ink rod in a quill pen. Branching from the rachis are smaller shafts called barbs, and then branching from the barbs are even smaller filaments called barbules. But this specimen lacked the rachis; it just had barbs and barbules down its ribbonlike tail.

“They are more fuzzy than sleek,” Dr. McKellar said. “It shapes our view of how feathers came to develop in modern birds, and it gives us a rare glimpse of what dinosaurs looked like and potentially what feathers were being used for in the mid-Cretaceous.”



The finding suggests that the barbs and barbules evolved before the rachis in feathers. That is interesting because the rachis seems to aid in flight. It could be that dinosaurs with more primitive feathers used them for temperature regulation, camouflage and visual signaling, rather than flight.

“It’s a spectacular specimen,” said Mark Norell, a paleontologist from the American Museum of Natural History, who was not involved in the study. He added that because the feathers were found with the vertebrae, there was no question they belonged to a nonavian theropod dinosaur as opposed to a prehistoric bird. “This is a novel feather type that we haven’t seen before.”

Wednesday, December 7, 2016

“Flapping First” Hypothesis


To most outside observers, birdwatchers can sometimes come across as being a little too silly, or even over-the-top, in their everyday pursuit of avian fulfillment. Whether it’s tending to one’s special life list or chasing after rarities at the drop of a hat, the attention of serious birders seldom stray away from the vagrants themselves. It’s also not too much of a stretch to say that today’s birdwatchers, and the birdwatchers of yesteryear, are two very different animals. In fact, the birding establishment has done a great job over the last few decades, intended or not, of taking the “watch”, out of birdwatching, and making it more about personal achievement.   

Not this birdwatcher. Despite my busy schedule, I still manage to find the time to watch and study bird behavior no matter what the situation may be. Since birds can be found on all major land masses from the poles to the tropics, and bodies of water in between, locating a subject is hardly ever a problem.

Just yesterday, I spent a few moments watching Fish Crows and Ring-billed Gulls bickering over a discarded McDonald’s bag in a Walmart parking lot and a pair of Common Raven secretly dumpster diving behind a popular Asian grocery store. Not the most glorious of places to watch birds, but it can still offer a wonderful learning experience.   

One of my favorite places to observe bird behavior is at my very own backyard bird feeder. The ideal way to hold a bird’s attention, my feeder allows me to detect a pecking order among hungry species, where in the forest birds prefer to eat and how species react to the presence of a predatory hawk.

The most frequent of backyard visitors is the much-maligned Blue Jay. A beacon of colorful light in an otherwise dull winter’s landscape, the Blue Jays aggressive behavior toward smaller birds is often frowned upon by well-intentioned homeowners.

Arriving in noisy flocks of ten to fifteen birds, Blue Jays are typically spotted ground feeding, gorging on fallen seed and bits of suet. However when pickings are slim, Blue Jays quickly become impatient and will flutter onto the tube feeder in a comical balancing act of gluttonous gratification.

 
Blue Jay ground-feeding
Photo Credit: Paul G. Cianfaglione

But was this comical balancing act a sign of evolutionary incompetence on the part of the Blue Jay, or was there more going on here than meets the eye?

Clinging desperately to a short perch, the Blue Jay employed a series of wing- flaps and tail-spreads just to maintain stability. At times, only one wing was needed to stay balanced, while at other times, the tail was pumped up-and-down. An oversized bird struggling to right itself on a feeder tube, the Blue Jay was nonetheless very successful at acquiring food.


Blue Jay clinging to tube feeder
Image Credit: Paul G. Cianfaglione
Blue Jay flapping to produce lift
Image Credit: Paul G. Cianfaglione
Blue Jay using one wing and tail adjustment to right itself
Image Credit: Paul G. Cianfaglione
Blue Jay stability flapping
Image Credit: Paul G. Cianfaglione
A Blue Jay's predatory success and continued survival
Image Credit: Paul G. Cianfaglione

However, what intrigued me most about this Blue Jays behavior was not that it actually attempted to land and feed on the tube itself, but how successful it was at maintaining balance and producing lift with only a few forearm flaps and some minor tail adjustments.

I thought, huh, was this stability flapping by the Blue Jay a clue to how small feathered dinosaurs were able to attain rudimentary flight, and even more importantly, slightly out-of-reach foods?

As someone who has a great deal of interest in the latest information related to bird evolution, this would not have been an unusual question to have swirling through my mind.


Birds share many unique skeletal features with dinosaurs, including more than twenty species of dinosaur that have been collected with preserved feathers.

Debates about the origin of bird flight are almost as old as the idea that birds evolved from dinosaurs, which arose soon after the discovery of Archaeopteryx lithographica in 1862. Two theories have dominated most of the discussion since then: the cursorial ("from the ground up") theory proposes that birds evolved from small, fast predators that ran on the ground; the arboreal ("from the trees down") theory proposes that powered flight evolved from unpowered gliding by arboreal (tree-climbing) animals. A more recent theory, "wing-assisted incline running" (WAIR), is a variant of the cursorial theory and proposes that wings developed their aerodynamic functions as a result of the need to run quickly up very steep slopes such as trees, which would help small feathered dinosaurs escape from predators (Source: Wikipedia/Origin of Birds).

So how would a crow-sized bird like Archaeopteryx, or a feathered dinosaur like Caudipteryx zoui, behave if they were present in our yards today? Would their primitive body plan allow them to feed at a low-slung tube or platform feeder just like our very own Blue Jay? For the 150-million-year-old Archaeopteryx, the answer would have likely been yes.

Archaeopteryx documents the earliest known phases of avian evolution. This most ancient bird had large wings with flight feathers of comparable appearance and similar in number to the primary and secondary feathers of the wing of many modern birds. Archaeopteryx also had a long, feathered bony tail.

 
Archaeopteryx
With paid permission
Peter Schouten

The overall design of the forelimb of Archaeopteryx and other long bony-tailed birds was in many respects much more primitive and quite different from that of their living counterparts. The hand, for example, was substantially longer than the ulna and radius, with three long fingers ending in sharp claws. The shoulder girdle was also primitive on Archaeopteryx, with its wing socket facing sideways, limiting its flight muscles for high-amplitude wing beats that were typical of modern birds.

Another important factor was that none of the Archaeopteryx specimens preserves evidence of a breastbone, which in modern birds provides anchorage for the powerful flight muscles. While such muscles could have been anchored to a cartilaginous breastplate, the absence of a strong breastbone stresses the moderate capacity of its flight musculature.

 
Domestic Turkey Cartilaginous Breastbone
Photo Credit: Paul G. Cianfaglione

Despite these skeletal limitations, most scientist feel the body plan of Archaeopteryx speaks of an animal that might have had an aerodynamic performance similar to today’s landfowl or rails; clearly, it was a weaker and less maneuverable flier than most flying birds today. In fact, new estimations of the wing loading and wing beat frequency of extinct birds based on the statistical relation between these aerodynamic parameters and the proportions of the wing bones in modern birds suggest that Archaeopteryx was most likely incapable of any prolonged flapping flight ( Source; Birds of Stone, Luis Chiappe 2016).  

So where does this leave our backyard Archaeopteryx? I see Archaeopteryx as a predominantly terrestrial predator, like today's Greater Roadrunner, who used its feathered forelimbs for short gliding jumps, leaping and lifting onto low branches (or bird feeders!) from the ground to access food and escaping predators themselves.

Another plausible scenario finds the early bird leaping and flapping after flying insects or plucking small reptiles from overhanging vegetation. Here, food becomes the driving evolutionary force for rudimentary take-offs.

 
Hypothetical backyard feathered dinosaur

Archaeopteryx’s ability to fly onto the platform feeder allowed it chase after birds like titmice and jays. If it did capture a larger prey item like the Blue Jay, Archaeopteryx would have used its weakly curved ungula claws to hold down its prey, using stability flapping as balance to stay on top of the struggling modern bird as it made its kill, similar to what we see in today’s predatory hawks (aka, mounting). Again, another powerful evolutionary force for the use of feathered forelimbs.

 
Image Credit: Emily Willoughby
http://emilywilloughby.com/gallery/paleoart

How about the turkey-sized Caudipteryx? Caudipteryx featured 14 symmetrical large feathers projecting from the outer half of the forelimbs as well as a curious tuft of vaned feathers fanning out from the end of a short tail. Fossils of Caudipteryx show that the longest forelimb feathers, reaching up to eight inches long, were flanked by shorter ones toward both the tip and at the base, a pattern identical to what we see in the wings of present-day birds (Source; Birds of Stone, Luis Chiappe 2016). 

The long vaned feathers and tail feathers may have offered Caudipteryx some aerodynamic advantage, but its short arms and overall proportions (heavy body) of these animals tell paleontologists that they were incapable of taking off. Instead, I believe Caudipteryx used its feathered forelimbs and tail for sexual displays and during courtship. The feathers on the wings would have also provided Caudipteryx with balance and the necessary lift while navigating difficult land surfaces and hills.

 
Caudipteryx zoui
With paid permission
Image Credit: Peter Schouten

In my hypothetical backyard scene, Caudipteryx would have been found under my feeder tray like a Wild Turkey, cautiously watching as it fed on fallen sunflower seeds. Caudipteryx may have been too heavy to propel itself into the air, but its strong leg muscles and ability to flap its short feathered wings could have enabled it to just barely lift onto my platform feeder.




Interestingly, we almost certainly know that Caudipteryx would have loved to eat sunflower seeds based on fossils showing that gastroliths were preserved in the position where the animals’ gizzards would have been (Source; Wikipedia).

Yes, grouping fossils into behavioral categories is difficult and relies on making broad generalizations. Archaeopteryx could have climbed trees if it wanted to. Its body size, limb proportions, forelimb orientation and hand and foot anatomy clearly allow this sort of behavior (Source; Naish, Darren. 2012. Tetrapod Zoology, Did Archaeopteryx climb trees?). But that doesn’t explain why Archaeopteryx, if it did spend time in trees, preserved so many primitive features while evolving modern forearm feathers. If it was that transitional of a creature, you would think there would be more give-and-take observed. Archaeopteryx still retained so many dinosaurian elements, long hands, shoulder girdle, pelvis, and feet were distinct, not fused and reduced as they are in living birds.

The idea that rudimentary take-offs evolved long before powered flight may seem counter-intuitive. For a ground-dwelling dinosaur in the earliest moments of avian evolution, there are a number of good reasons why it might have wanted to leap into the air, without feeling the need to stay there. The demands to find food, I believe, is at the top of the list.

Our Blue Jay righting itself on my tube feeder demonstrates that even a weak flapping capability could be employed for balance and rudimentary flight, affording a greater chance of predatory success, and their continued survival.  

Learn more about this intermediate step toward powered flight below;