Saturday, February 25, 2017

The Art of Archaeopteryx


I had the opportunity over the weekend to visit the Peabody Museum of
Natural History in New Haven Connecticut for a special exhibit called; The Art of Archeaopteryx, Dinosaurs Take Flight.

Here is a brief summary of the art show and a couple photos of the featured artists work, Rudolph Zallinger, Luis V. Rey, Julius Csotonyi, Mark Hallett, William Stout and Gary Staab.

Dinosaurs Take Flight presents not only the history and science behind Archaeopteryx but also engages visitors at the intersection of art and science. Throughout the gallery, six renowned artists from around the world provide a glimpse into their studios and processes as they bring this iconic “missing link” back to life.



William Stout Archaeopteryx Artwork
Photo Credit: Paul Cianfaglione
William Stout Archaeopteryx Artwork
Photo Credit: Paul Cianfaglione
Julius Csotonyi Archaeopteryx Artwork
Photo Credit: Paul Cianfaglione
Julius Csotonyi Archaeopteryx Artwork
Photo Credit: Paul Cianfaglione
Julius Csotonyi Archaeopteryx Artwork
Photo Credit: Paul Cianfaglione
Luis V. Rey Childhood Artwork
Photo Credit: Paul Cianfaglione
Luis V. Rey Archaeopteryx Artwork
Photo Credit: Paul Cianfaglione
Luis V. Rey Archaeopteryx Artwork
Photo Credit: Paul Cianfaglione
Mark Hallett Archaeopteryx Artwork
Photo Credit: Paul Cianfaglione
Dinosaurs Take Flight; The Art of Archaeopteryx
Featured Artist Mark Hallett
Photo Credit: Paul Cianfaglione
Dinosaurs Take Flight; The Art of Archaeopteryx
Photo Credit: Paul Cianfaglione

There also happened to be another event going on at the same time called “Dinosaur Days”

From the 150-million-year-old Brontosaurus skeleton in the Great Hall to the award-winning, life-sized sculpture of Torosaurus outside, dinosaurs and the Yale Peabody Museum go hand in hand. Join us for our annual celebration of paleontology and dinosaurs. There will be plenty of hands-on activities for the whole family, including our famous fossil dig and an extensive fossil touch table. And you’ll have the chance to meet paleontology graduate students and professionals and learn about their interesting research.

Rudolph Zallinger Archaeopteryx Artwork
Photo Credit: Paul Cianfaglione

Dinosaur Days at the Peabody Museum New Haven Connecticut
Photo Credit: Paul Cianfaglione

Dinosaur Days at the Peabody Museum New Haven Connecticut
Photo Credit: Paul Cianfaglione

Sunday, February 19, 2017

Oldest Known Fossil Bird Syrinx

When I think about recent avian paleontological news, my mind at this time settles on amber inclusions of dinosaur tails and complete wings, or the plumage colors on a 130-million-year-old bird fossil. But when I was informed by some friends about the discovery of a 66 million-year-old fossilized syrinx, I was astonished, and a little skeptical to say the least.


In a new paper titled “Fossil evidence of the avian vocal organ from the Mesozoic”, researchers describe the first remains of a fully-formed fossil syrinx on the late Cretaceous specimen of Vegavis iaai.


The syrinx, the avian vocal cord, is unique among all vertebrates. As opposed to the mammalian larynx, which is located at the top of the trachea and contain hard membranes that are controlled by a complex set of muscles and cartilage, the forked syrinx is uniquely situated at the lower end of the trachea, becoming a fine resonating chamber with vibrating membranes. It’s this special design which allows birds to control and sing two different notes at the very same time.

 
Syrinx Diagram
Photo Credit: Studyblue.com

Multiple online science sites covered the news including Live Science, which presented one of the best pieces on the fossils discovery. 


Vegavis iaai, known from a fragmentary skeleton that shows that the species was long-legged primitive member of the duck, goose and swan lineage, possibly similar to modern basal anatoids like screamers and magpie-geese (Source: A Field Guide to Mesozoic Birds and other Winged Dinosaurs, Martyniuk, Matthew 2012).



Vegavis iaai
Image Credit: Michael Skrepnick

The story provided some very interesting thoughts on the find, but it also offered some conflicting information.

In it, the researchers are said to have scanned the syrinxes of 12 modern birds and a 50-million-year-old fossilized syrinx from Wyoming dating to the Eocene epoch. The scientists found that the V. iaai syrinx is asymmetrical, much like that of a modern female duck. This suggests that the extinct bird made honking, quacking or whistling noises with the right and left branch of the organ.

The finding confirms that the syrinx evolved during the Mesozoic Era, the age of the dinosaurs. Now that scientists know that the syrinx — which is made of cartilage and often degrades too easily to remain in the fossil record — can be preserved, it's unclear why no syrinx remains have been found in dinosaurs, the researchers said.

Intrigued, I decided to do my own online research regarding the possibility of ossified syrinxes in modern birds. In the end, it was clear that the assumed composition of the syrinx in modern birds are not wholly cartilaginous, but in fact partially ossified.

Some examples of this included WikiVet, which mentions the syrinx as being composed of ossified cartilages, with a male swan having an enlarged osseous bulla on the left side of the syrinx which acts as a resonator.

The 1982 paper “Ossification of the laryngeal, tracheal and syringeal cartilages in the domestic fowl” points out that in the syrinx, mineralisation regularly occurred only in the pessulus and in the base of the first bronchial syringeal cartilages. In some birds, it was also encountered more caudally in the cartilages of the primary bronchi. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1167936/pdf/janat00217-0064.pdf

Also interesting was a study in Vertebrate Zoology titled, “The peculiar syrinx of Rhea Americana (Greater Rhea, Palaeognathae). Male Rheas, which are described as more primitive and reptilian than other birds, is another species examined who clearly shows a syrinx with an osseous component to it.

Knowing now that part of the syrinx can be ossified in many of today’s birds, I am also starting to wonder why no syrinx remains have been found in dinosaurs. Is it possible that fossil syrinxes have just been overlooked?

The article in Live Science also goes on to say that "Perhaps birds, which evolved from the mostly meat-eating, bipedal theropod dinosaurs, developed the syrinx after they learned to fly and acquired improvements in breathing and metabolism that helped it fly and sing. This suggests that dinosaurs did not have syrinxes, and so couldn't sing like birds do, the scientists added".

Perhaps. Or did improvements in breathing and metabolism happen prior to flight, in small, active theropods? Wouldn’t bipedality alone improve breathing and metabolism just the same? If that’s so, could song have been the communication of choice long before the evolution of display feathers? Or if learning to fly was a prerequisite to a syrinx and song, would this be in any way further proof that larger, bird-like dromaeosaurids, who may in fact have been secondarily flightless, sang?

Utahraptor
Image Credit: Emily Willoughby

Please visit one of my favorite paleoartist Emily Willoughby here:





Again, the male Greater Rhea, who are described as more primitive and reptilian than other birds and that through evolution lost the ability to fly, may provide a living model of this.


The researcher was also quoted as saying; "I had actually started thinking about the fossilization potential of the syrinx, I was shocked to find that this fossil, which had actually been in my lab for a number of years, had a fossil syrinx."

In response to this, someone in an online forum mentioned “I think a lot of people, in the wake of this paper, will start looking around at their theropod fossils, and in a few years from now we'll see a few more syrinxes being described from unexpected taxa”. Let us hope!

Still captivated by the talk of fossil syrinxes, I decided to take a closer look at my own specimens. Sorted away within the skeleton of an American Crow was a peculiar object, which surprisingly came away unscathed from my cleaning and straining methods. Incidentally, crows and ravens are two of the largest species in the suborder Oscines, the “songbirds”.

American Crow
Songbird
Photo Credit: Paul Cianfaglione
I placed the piece under a stereo-microscope for careful study. After a few seconds of observation, and to my utter surprise, I said hey! this is a syrinx! I couldn’t believe my eyes, or be happier!

American Crow Syrinx
Photo Credit: Paul Cianfaglione

American Crow Syrinx
Photo Credit: Paul Cianfaglione


American Crow Syrinx
Photo Credit: Paul Cianfaglione

Honestly, if it wasn’t for the article in Live Science, I may never have recognized or even looked for this vocal organ.

See related blog post here;


Even crazier was seeing how similar the American Crow syrinx is compared to the fossil syrinx of Vegavis iaai! Not only did it have the same structure as MACN-PV 19.748, but the forked openings appear to be slightly asymmetrical.


Image Credit: Nicole Fuller Sayo Art for UT Austin
The syrinx of the Vegavis iaai (top and left) has an asymmetry seen in living ducks. This likely helped the ancient bird make honk-like calls. The bird's vocal organ is likely a transition between that of crocodiles (right) and modern birds.

So how important was this fossilized syrinx discovery? Franz Goller, a co-author and physiologist at the University of Utah, said the study is the beginning of the work to determine what the fossilized organ can tell us about the sounds of early birds.

“Here, we begin to outline how fossilizable characteristics of the syrinx may inform us about sound features, but we need a lot more data on living birds,” Goller said. “Remarkably, prior to this work, there is almost no discussion of these important questions.”

Read more here; https://news.utexas.edu/2016/10/12/oldest-known-squawk-box-reveals-dinosaurs-likely-didn-t-sing

Wednesday, February 8, 2017

Ancient DNA From A Feather Calamus


Ever since the movie Jurassic Park came out in 1993, the world has been fascinated with the idea of cloning dinosaurs from ancient DNA.

Unlike most movies, Jurassic Park suggested a real-life scenario which saw a female mosquito taking a blood meal from a dinosaur immediately before becoming entombed in sticky tree resin.

This made sense to a lot of people, since many plants and animals were already found preserved in amber dating back to as far as 130 million years ago.

But according to some researchers, the recovery of ancient DNA in amber fossils is highly unlikely. Original studies of amplified ancient DNA proved problematic, due to the introduction of outside contamination into test samples.

Also, if researchers did find a perfectly preserved mosquito with a body full of dinosaur blood, retrieving its DNA would still be difficult. The blood with the dinosaur DNA would be surrounded by the body of an insect, which has its own DNA. (Source; Tracy V. Wilson) http://science.howstuffworks.com/environmental/earth/geology/dinosaur-cloning.htm

Most scientist have now abandoned the search for DNA in amber.

However since that time, some incredible discoveries have been made, including the first dinosaur tail found trapped in amber and two complete ancient bird wings.

Ancient Bird Wing Trapped in Burmese Amber
Both of these pieces were obtained from northern Myanmar (also known as Burma), which is the only Cretaceous amber deposit in the world that is exploited commercially, and dates to around 105 million years.



Image Credit: cheung chung

Sparked by the recent finds, I decided to take another look at my own collection of Burmese amber. Found in the collection are chosen pieces of amber purchased solely for their beautiful inclusions of bird/dinosaur feathers.

One piece in particular, described as a “Feather & Diptera Dolichopodidae Inclusions in Burmite Amber”, piqued my interest.

No, it wasn’t the nicest specimen in my collection, but it held something my other amber feathers didn’t. Located near the base of the feather, where the last of the barbs are found growing off the rachis, is what appears to be a thicker and more tubular part of the feather shaft. To make sure I wasn’t looking at a distorted image, I placed the amber under a stereo microscope and turned it into different positions. After confirming its tubular shape, I wondered, could this be the feathers calamus? If so, was this discovery in any way significant?



Mourning Dove Feather Calamus
Photo Credit: Paul Cianfaglione
Burmese Feather Calamus
Photo taken by IPhone through microscope
Photo Credit: Paul Cianfaglione


Burmese Feather Calamus
Photo taken by IPhone through microscope
Photo Credit: Paul Cianfaglione

Not long ago, I remember reading an article on the internet titled, “DNA content and distribution in ancient feathers and potential to reconstruct the plumage of extinct avian taxa”.


In it, researchers analyzed extinct subfossil moa feathers from Holocene New Zealand rockshelter sites and demonstrate that both ancient DNA and plumage information can be recovered from feathers, allowing species identification and a means to reconstruct the appearance of extinct taxa.

A subfossil (as opposed to a fossil) is a bone or other part of an organism that has not fully fossilized. This may be because not enough time has elapsed since the animal died, or because the conditions in which the remains were deposited were not optimal for fossilization (Source; Wikipedia).

In short, the results of the study state that the presence of DNA in the rachis and barbs, as well as the calamus, of moa and modern emu feathers suggests that multiple parts of a feather may contain DNA, providing a method for genetic analysis requiring minimal destruction of valuable specimens.

Previous to this, the calamus was the go-to portion of the feather to successfully extract DNA. However, because the calamus is commonly absent from subfossil feathers (owing to breakage before, or during, deposition), the recovery of DNA from distal feather components would have major implications for historical and ancient DNA research.

This is interesting to know. If researchers were already extracting DNA from the calamus of sub-fossil feathers in historical museum specimens, why weren’t they targeting the perfectly entombed calamuses in 100 million-year-old amber? It’s odd to think that when given the choice, extracting DNA from a mosquito in amber, or extracting it from a feathers calamus, most would elect to choose the long-shot mosquito. At least that’s what the movie people, consultants and some scientists did! 

As a fan of the first couple Jurassic Park movies, I’d like to know, could the proper institution today extract DNA from the calamus of a feather in Burmese amber? Apparently not.

In another paper published in 2013 titled, “Absence of Ancient DNA in Sub-Fossil Insect Inclusions Preserved in ‘Anthropocene’ Colombian Copal”, researchers have revealed that this extracting technique is unlikely to succeed. Below is an online article from SCI NEWS explaining their attempt;

They used highly-sensitive sequencing techniques – the most advance type of DNA sequencing – on insects in copal, the sub-fossilized resin precursor of amber.

COPAL is NOT TRUE FOSSIL AMBER but a much younger form of tree resin.  There IS a difference (age alone most obviously) and it can be identified.  Furthermore, copal contains inclusions of modern living life-forms whereas true fossil amber contains inclusions mostly of EXTINCT prehistoric life. Source;


The study was conducted wearing full forensic suits in an ancient DNA facility, which comprises a suite of independent, physically isolated laboratories, each with an ultra-filtered air supply maintaining positive displacement pressure and a managed access system.

“In the original 1990s studies DNA amplification was achieved by a process called the polymerase chain reaction (PCR), which will preferentially amplify any modern, undamaged DNA molecules that contaminate an extract of partially degraded ancient ones to give false positive results that might be mistaken for genuine ancient DNA,” explained senior author Prof Terence Brown.

“Our approach, using ‘next generation’ sequencing methods is ideal for ancient DNA because it provides sequences for all the DNA molecules in an extract, regardless of their length, and is less likely to give preference to contaminating modern molecules.”

The scientists concluded that their inability to detect ancient DNA in relatively young – 60 years to 10,600 years old – sub-fossilized insects in copal, despite using sensitive next generation methods, suggests that the potential for DNA survival in resin inclusions is no better, and perhaps worse, than that in air-dried museum insects. (or moa feather calamuses in this case) I find this very surprising.

This raises significant doubts about claims of DNA extraction from fossil insects in amber, many millions of years older than copal.

“Intuitively, one might imagine that the complete and rapid engulfment in resin, resulting in almost instantaneous demise, might promote the preservation of DNA in a resin entombed insect, but this appears not to be the case. So, unfortunately, the Jurassic Park scenario must remain in the realms of fiction,” Dr Penney concluded.

For more SCI NEWS articles please see here;


 
Image Credit: http://www.globalburmiteamber.com/
Burmese Amber with feather inclusions
Despite these failed attempts at extracting ancient DNA, the good news is that discoveries and studies about 100 million-year-old Burmese amber is becoming more and more prevalent. While feathers have in the past been found associated with fossils of dinosaurs and ancient birds, this is the first time that scientists are clearly able to study and observe well-preserved feathers, and now body parts, in three-dimensional form, revealing a much finer level of structural detail.