Thursday, November 30, 2017

Rapidly evolving bird beaks

In case you missed it, an article worthy of more attention; 

New York Times Article by DOUGLAS QUENQUA NOV. 28, 2017In 

Things Looked Bleak Until These Birds Rapidly Evolved Bigger Beaks

Conservationists have been sounding the alarm over invasive species for years, warning of the damage they can cause to habitats and native animals. But in Florida, an invasive snail might be helping an endangered bird species come back from the brink, researchers say.

The population of North American snail kites — birds that use curved beaks and long claws to dine on small apple snails in the Florida Everglades — had been dwindling for years, from 3,500 in 2000 to just 700 in 2007. Things began to look particularly bleak in 2004, when a portion of the Everglades was invaded by a species of larger snail that the birds had historically struggled to eat. Ornithologists assumed the shift would hasten the snail kite’s decline.

A North American snail kite in Florida. Researchers say the bird species has rapidly evolved larger beaks and bodies to eat a larger, invasive snail.
 Credit Robert Fletcher/University of Florida 
http://avianmusing.blogspot.com/
But the number of snail kites in the Everglades grew over the decade following the invasion of the larger snails. The reason, according to a study published Monday in Nature Ecology and Evolution, is that the snail kites have rapidly evolved larger beaks and bodies to handle the bulkier snails.

“We were very surprised,” said Robert Fletcher, Jr., an ecologist at the University of Florida and an author of the study. “We often assume these large-bodied animals can’t keep up with changes to the system, like invasions or climate change, because their generation times are too long. And yet we are seeing this incredibly rapid change in beak size of this bird.”

Dr. Fletcher and his colleagues analyzed 11 years of morphological data they had collected on the birds. Because snail kites can live to the relatively old age of 8, that time period represented fewer than two generations for the birds.

Nonetheless, the researchers found that beak and body sizes had grown substantially (about 8 percent on average, and up to 12 percent) in the years since the invasion.

Exactly how the birds are pulling off this evolutionary trick is not clear, but natural selection does appear to play a part. Young snail kites with larger bills were more likely to survive their first year than snail kites with smaller bills, presumably because the large-billed birds were better able to eat the invasive snails.

The invasive snails are two to five times larger than the native species, and young kites with larger bills that were able to feed on them were more likely to survive their first year.

Robert Fletcher/University of Florida
http://avianmusing.blogspot.com/
Young birds eating the invasive snails, which are two to five times larger than the native ones, were also growing faster than birds weaned on the smaller ones, which may account for the increase in overall body size.

But the researchers found suggestions of a genetic component to the changes, as well. By tracking the birds’ pedigrees, they found that large-beaked parents gave birth to large-beaked offspring, setting the stage for large-scale evolutionary change.

Thirteen years after the larger snails invaded, the population of the birds has nearly tripled, to “well over 2,000,” Dr. Fletcher said. “It’s been a major development for the recovery of this species.” Outside of Florida, related snail kites are found in parts of South America, Central America and the Caribbean, where they are not considered endangered.

Overall, the findings are good news for animals squaring off against invasive species or other rapid habitat change, including global warming. “This work illustrates very clearly that these large top predators can respond to invasions at a rate much quicker than most people have ever imagined,” Dr. Fletcher said.

Saturday, November 25, 2017

Avian sternum evolution and developmental strategies

Finding answers to my peculiar scientific questions can sometimes be frustrating, especially when it pertains to a bird that has not fully developed yet. The bird I’m eluding to, whose weathered bones were found sitting at the bottom of a small cup nest, was juvenile in nature. Despite its very early age, many of the small bones were surprisingly familiar to me.

Salvaged from the nest were a tibiotarsus, ulna, carpometacarpus, and even a femur. Some of the bones uncovered were still in the process of development, like an unfused tarsometatarsus.
Juvenile bird bones
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
As excited as I was about these discoveries, there were other bones that were flat-out unfamiliar. One bone in particular was quite large, in comparison to the rest, and oddly shaped like a fossilized shark tooth. Where did this puzzle piece go?


Possible juvenile bird sternum
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
After some gritty research, and with much consideration, I came to a tentative conclusion that this bone was most likely part of the sternum. Was I correct? Granted, there isn’t much material out there regarding immature bird sternum identification, but I did manage to find a scientific paper with excellent information and possible clues.

Titled; “Insight into the early evolution of the avian sternum from juvenile enantiornithines”, the paper describes several new specimens of exceptionally well-preserved early juvenile enantiornithines fossils that, together with previously described specimens, show how the sternum, like in living birds, is a complex bone formed by several elements.


Sternal complexity comparable to living birds (for example, caudally extending processes, ventrally projecting carina) only appears in Ornithothoraces, the clade that includes the above mentioned Enantiornithes, the dominant group during the Cretaceous, and Ornithuromorpha, the group that includes living taxa (Neornithes).

However, the question still remained; could this paper provide enough information to support my claim?

Below are some excerpts from the paleontological study that I felt were pertinent to my investigation.  

To be clear, I believe this bone may well be part of the mesial caudal process, as depicted in the book; Avian Osteology by Gilbert, Martin and Savage, 1996. 
Mesial caudal process of sternum
Book photo credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
*The sternum of IVPP V15564 (institution where fossil is housed and catalog number) preserves three ossifications. The largest is caudally located and vertically symmetrical. Proximally, it forms a fan-shaped body with a convex rostral margin; distally it forms a long xiphoid process that always exceeds the rostral body in length. A slight ridge is present on the midline of this ossification, restricted to the caudal half; we infer this to be an early stage in the development of the osseous keel (Fig. 2e). This ossification has been previously observed in juvenile enantiornithines.


Figure 2, Enantiornithines sternal region
Photo Credit: http://www.nature.com/articles/ncomms2104
My thoughts after reading that were; could this juvenile bird bone be part of the caudal region, with the start of a long xiphoid process? During an early stage of growth, did sternal ossification in extant bird’s mirror enantiornithine development in any close way, prior to becoming surrounded by bone?


*Basal ornithuromorphs and enantiornithines show similar sternal morphologies, which suggests the fully modern sternum evolved only among more derived members of Ornithuromorpha, the Ornithurae. Unfortunately, no early juvenile ornithurines are recognized; however, given the derived appearance of the sternum we infer that development may have proceeded similarly to that of living birds. This is supported by the ossification of the sternum from a single pair of plates in most paleognaths indicating the plesiomorphic dinosaurian condition was retained in the lineage leading to modern birds. Enantiornithines are already known to have a developmental strategy different from most living birds in which they grew slowly for many years and spent extended periods of time as subadults, as evidenced from the large number of juvenile and subadult specimens uncovered. These specimens reveal early ontogenetic stages that allow us to understand the skeletal development of the clade. What has become apparent from this study is that, despite its superficially similar appearance, the enantiornithine sternum formed very differently from that of non-avian dinosaurs and living birds.

Again, the same question keeps coming to mind; in spite of its differing formation, would it be possible to use fossilized enantiornithine sternums in comparative studies with extant bird sternums, especially at an early ontogenetic stage? We can certainly do this with the tarsometatarsus, which is unfused and clearly mirrors the dinosaurian condition. Although treated as a single bone, the tarsometatarsus is actually formed by synostoses; in living birds, metatarsals IIIV start to fuse at the mid-shaft and fusion proceeds proximally and distally.

Juvenile bird tarsometatarsus
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
*As in living birds, the basal bird sternum was incompletely ossified in juveniles. The sternum of enantiornithines developed from four to six ossifications (Fig. 3). As in the morphological description, the sternal ossifications of enantiornithines will be referred to by their positions: proximal, caudal, lateral (paired) and craniolateral (paired, variably present). Although we will attempt to correlate these with ossification centers observed in living birds, the apparent lack of homology causes us to refrain from naming these ossifications according to previous literature. Given the diversity in the number of ossification centers in living taxa (two to seven), it would not be unexpected that there is similar diversity within Enantiornithes.

Figure 3, Interpretive drawing of the development of the enantiornithine sternum
Image credit: http://www.nature.com/articles/ncomms2104
*Ossification proceeds from the caudal half proximally, which is opposite to the direction of sternal development in living birds. The main body of the sternum in enantiornithines is formed by two ossifications, as in birds and non-avian dinosaurs, but instead of a bilaterally symmetrical pair, they are two proximo-distally arranged vertically symmetrical ossifications of very different morphology.

The researchers attempt to correlate sternal ossifications of enantiornithines, with ossification centers observed in living birds, vaguely reminds me my own similar efforts to unlock this unusually shaped bone’s true identification, though in a layman’s way of course. 
Possible juvenile bird sternum
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
The last two paragraphs also contradict my initial thoughts about the sternal development of this juvenile bone, leaving me once again frustrated.

I finally turned to a couple of wood warbler specimens that I have currently stored in my own collection. The one that held the most promise for side-by-side comparison was the Yellow Warbler (Setophaga petechia), which was not only my best-preserved specimen, but whose discovered nest matched perfectly to the species preferred breeding habitat and site location where it was found.  

Pinpointed under the microscope were two prospective sites. The first returned my attention to the mesial caudal region, where it looks as if the bone once again may be part of the sternum, and the initial formation of the sternal crest or keel.

Yellow Warbler (Setophaga petechial) sternum
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
Another possibility is the skull, more precisely the nasal-frontal region (Proctor; Manual of Ornithology. 1993). I feel less strongly about this option, but it is similar in shape and has to be considered.

Yellow Warbler (Setophaga petechial) nasal-frontal region
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
Then there is the chance that I am completely overlooking another location for this bone.

As I mention earlier in this post, there really isn’t much information out there regarding this topic, and when it is, it’s usually long outdated. For instance, some of the information cited in the paleontology paper date from 1868, 1939, 1960 and 1980. Images were also very hard to come by.    

Even though this may have been a futile attempt at scientific inquiry, I did foster a new-found appreciation for the development of the avian sternum. This study also helped satisfy my continuous need to learn more about the close relationship between birds and dinosaurs.

Saturday, November 11, 2017

Archaeopteryx toy figures; how scientifically accurate are they??

As a follow-up to my pictorial book review of Archaeopteryx; The Icon of Evolution by Dr. Peter Wellnhofer (see November 1st, 2017), I thought it would be interesting, and fun, to see how Archaeopteryx’s scientific restoration of its skeletal and outer appearance in life, compares with todays mass-produced toy figures. 


Archaeopteryx, The Icon of Evolution
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/

Toy figures, which are often sold in Natural History Museums, have a pretty strong following. So strong, that companies such as CollectA, Papo, Safari Ltd, Carnegie and Schleich continue to produce new figures, just to keep up with the public’s demand. These toys are not only manufactured for kids, but are now the target of more serious adult collectors. 

This has led to the creation of online communities dedicated solely to the discussion of prehistoric animal collectibles, paleoart, pop culture, and paleontology.


It is in these forums that eagerly awaited models are introduced and critiqued for their scientific accuracy and artistic originality. 

I will be evaluating five Archaeopteryx figures today for accurate feather placement, teeth, wing claws and overall shape. Another important feature is plumage coloration. 


Archaeopteryx Toy Figures
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
In 2011, graduate student Ryan Carney and colleagues performed the first color study on an Archaeopteryx specimen. Using scanning electron microscopy technology, the team was able to detect the structure of melanosomes in the single-feather specimen described in 1861 (Source: Wikipedia). The resultant structure was then compared to that of 87 modern bird species and was determined with a highest likelihood to be black.

At the conclusion of each evaluation, I will rate the figure from 1 through 10, based on the key features mentioned above. I will also take a more thorough look at the first figure, letting the reader revert back to this evaluation for further reference. 

Wild Safari by Safari Ltd. 

Since I just touched on the topic of Archaeopteryx’s recently discovered black coloration, it only seems right that I start with an actual black-colored figure. Wild Safari’s toy figure offers consumers the best of both worlds. It not only has the ability to inspire young kids, but satisfy the pickiest of adult collectors.

The black colored plumage with iridescent sheen is beautifully done, as well as scientifically accurate. In many places the finer structures of the feathers can be determined, especially the barbs branching off the shafts. The feathered lower leg corresponds well with preserved feathers in the Berlin specimen. In general, the feathers throughout the figure are positioned correctly.


Wild Safari Archaeopteryx
Photo credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
The figures structure is proportionally sound. I like the way you can see the curves of the body, long s-shaped neck, chest, even leg musculature. The skull is the appropriate size and shape, with a nicely done eye. Teeth are fully present. 

A couple downfalls of the Wild Safari Archaeopteryx figure include the exaggerated hyper-extensible sickle-clawed second toe. Though its supported by some researchers, Wellnhofer states that such a function would appear to be quite impossible, the more so as the ungual and its keratinous claw of the second toe is of normal size. It is obvious that a greater extension of the second toe was possible in Archaeopteryx, but there is no evidence as to which special function this toe should have been adapted (Wellnhofer; 2009). 

The fingers of the hand, according to the book, are also incorrectly reconstructed. The first should be sticking out freely, while the second and third digits only the claws are protruding. Speaking of claws, I don’t understand the blunt-ended nature of both the finger and toes. It looks a little unusual.  

My final problem with the figure involves the feathers of the wing. The fact that all flight feathers in the wing were preserved in their natural position (fossil specimens), and not separated from the bone, is indirect evidence for their firm connection. With that being said, the long humerus is devoid of feathers. This suggests that there was a gap in the plumage between the inner wing (secondaries) and the body (Wellnhofer; 2009). There is no sign of a gap between the secondaries and body on this figure.

Even with these faults, the Wild Safari Archaeopteryx is a well- researched and an almost perfect reconstruction. Rating: 8

Papo Archaeopteryx

At first glance, you may mistake this figure for another feathered raptor, like the Bullyland Velociraptor. Despite being similar to other famous raptors on the market, the Papo Archaeopteryx does offer some unique attributes of its own.

The feathers for one appear individually crafted, with a layered look, and feel that is rarely found on other toys today. Very well done. A gap in the plumage between the inner wing (secondaries) and the body is not present, however the tertials are noticeably shorter (partial credit for this).  

The tail on the Papo Archaeopteryx is spot-on according to the Wellnhofer book. Rectrices on the figure correspond well with the Berlin and London specimens, including the rounded feathers at its distal end. 


Papo Archaeopteryx
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
The artist choice for a brownish/cream color scheme is tastefully done.

The hand and toe claws are noticably sharp on this Archaeopteryx model.

The evenly-spaced teeth are another nice feature of this toy. Paleontologists and collectors alike will certainly recognize the importance of Archaeopteryx’s evenly-spaced teeth. In between the mandibular teeth interdental plates are developed, as documented in the Munich specimen for the first time (Wellnhofer. 2009). Except for Archaeopteryx, in no other toothed bird are interdental plates known.


Papo Archaeopteryx
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
Like all toy figures, there are some obvious discrepancies. The legs on the Papo Archaeopteryx are unfortunately a little off course. Their short-bulky appearance is reminiscent of body-builder’s physique. Also, the placement of the crural feathers extend further down onto the metatarsals than I would like to see, rather than ending on the tibiotarsus as preserved on the Berlin specimen. 

The fingers of the hand, according to the book, are also incorrectly reconstructed. The first should be sticking out freely, while the second and third digits only the claws are protruding.

The snout also seems to be a bit too robust, and more dromaeosaur-like. 

The most striking feature on this figure is located along its crown. Eighteen red quill-like feathers (or are they fleshy horns (lappets), create an unnecessary eye-sore on an otherwise nice toy figure. Was its inspiration taken from a Temminck's tragopan? Rating: 6


Temminck's Tragopan Taxidermy
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
Kinto Favorite Collection soft models Archaeopteryx

Here is another high-quality toy figure from the company, Kinto Favorite Collection soft models. The only Archaeopteryx figure to feature its own pedestal. 


Kinto Favorite Archaeopteryx
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
It is with this pedestal that the Kinto Archaeopteryx is able to be positioned in a running pose, which is in contrast to most figures that appear to be just ‘standing around’. This position also allows the collector to gauge the proportion of this model, which seems accurate.  

The feathers on this figure are adequately formed. They are detailed; however, it takes a microscope to find that out. The choice of colors is easy on the eyes. Dark, medium and light gray’s is about as close to scientifically accurate as you can get, without going there.   

The crural feathers are quite evident and corresponds well with preserved feathers in the Berlin specimen, especially on the extended leg. 

The tail on the Kinto Archaeopteryx is nearly perfect according to the Wellnhofer book. Rectrices on the figure correspond well with the Berlin and London specimens, including the rounded feathers at its distal end. I also like the constriction at the base of the tail which is consistent with the fossil evidence.

The wing and toe claws barely pass for acceptable, showing a slight sharpness to them. The hyper-extensible sickle-clawed second toe is discernable, but not in your face like Wild Safari’s.

The problems with this model include the fingers of the hand, which according to the book, are also incorrectly reconstructed. The first should be sticking out freely, while the second and third digits only the claws are protruding.

The gap in the plumage between the inner wing (secondaries) and the body is not present, with no effort to do so. 

I like the detail on the skull of this Archaeopteryx, however the design of the teeth left much to be desired, which is unfortunate. They are entirely missing on the lower mandible. Rating: 7


Kinto Favorite Archaeopteryx
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/

Archaeopteryx from PNSO

Even though the PNSO Archaeopteryx is not positioned on a stand-alone pedestal like the Kinto model, it still presents the toy in a highly unusual pose. As if caught in the act of a mating display, the PNSO Archaeopteryx features outstretched forelimbs, a tucked in leg and raised tail. This posture will allow for a more thorough examination of this figures details. 


PNSO Archaeopteryx
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
In many areas the finer structures of the feathers can be determined, especially the barbs branching off the shafts. Wing coverts have a layered look and feel to them, not an easy feature to get right on such a small replica. The feathered lower leg corresponds well with preserved feathers in the Berlin specimen. Overall, the feathers throughout this Archaeopteryx are positioned accurately. 

The brown and gray color scheme is an appealing and a safe choice, but mirrors the Kinto model almost to a tee. 

The figure, in general, appears properly proportioned.  

The fingers of the hand, according to the book Archaeopteryx; The Icon of Evolution, are correctly reconstructed. The first is sticking out freely, while the second and third digits only the claws are protruding. But there are imperfections. The claws on the fingers are blunt and one is painted over gray, not greenish-yellow like the other two. The claws on the toes are also rounded. 

The tail and its feathers are distally narrow, a possible necessity to keep this model balanced.

The gap in the plumage between the inner wing (secondaries) and the body is not present. 

Since the jaw is closed shut, it is hard to judge, or even see the teeth on this figure. However, it does show some similarities (under the microscope) to the Eichstatt specimen of Archaeopteryx showing a slight overbite, premaxillary and maxillary with teeth. Downfall, they are not painted and are virtually invisible. Rating: 6  

Bullyland Archaeopteryx (blue morph)

This will be my final review of Archaeopteryx toy figures. With its feet firmly secured to a small baseplate, the Bullyland Archaeopteryx features a forward leaning posture which allows its tail to be lifted to near horizontal plane. Curiously, this posture contrasts sharply with all the other Archaeopteryx figures which show tripod, wing and pedestal support. 

There are feathers located throughout the body on this figure, but only on the wing does one find feathers individually sculpted. Beyond that, there is no other finer details.  The feathers on the lower leg do not correspond with preserved feathers in the Berlin specimen.

The tail on the Bullyland Archaeopteryx appears too short, lending to an already front-end heavy appearance. Rectrices on the figure correspond well with the Berlin and London specimens, including the rounded feathers at its distal end. 

Clearly the most accurate feature on this Archaeopteryx figure is the gap in the plumage between the inner wing (secondaries) and the body. Finally, I can state that yes, the gap is present! 


Bullyland Archaeopteryx
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
Plumage coloration itself is adequate at best. 

The fingers of the hand are all incorrectly reconstructed. All three digits protrude beyond the feathering. Claws on the fingers are curved and barely pass for sharp. Same goes for the toe claws.

The skull has a long, bizarre look to it. This Archaeopteryx looks as if its grinning, showing off its horribly designed teeth. Ranking: 4

Wednesday, November 1, 2017

Archaeopteryx; The Icon of Evolution. A Pictorial Book Review.

A few months ago, I attended the opening of a new exhibit at the Yale Peabody Museum titled; Dinosaurs Take Flight, The Art of Archaeopteryx. The exhibit 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.


Dinosaurs Take Flight; The Art of Archaeopteryx
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
As is with all of my visits to the Peabody Museum, a stop in the museum shop is always a must. Here our family found plenty of toy dinosaur figures, coffee mugs, jewelry, and of course, dinosaurs books. 

To showcase the days attraction, the Peabody offered a variety of items related to Archaeopteryx. It is here where I found the book Archaeopteryx; The Icon of Evolution by Dr. Peter Wellnhofer (2009). It’s an impressive book, both in size (10 x 13 inches) and substance. Packed with quality photos and information, it didn’t take me long to make a decision, and subsequent purchase. 


Archaeopteryx; The Icon of Evolution. Peter Wellnhofer
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
Divided into ten chapters, Archaeopteryx; The Icon of Evolution covers many interesting topics such as the size, growth and life history of Archaeopteryx, as well as plumage and physiology.


Archaeopteryx; The Icon of Evolution. Peter Wellnhofer
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
It even contains chapters of the world-famous Solnhofen lithographic limestone, covering aspects of its geology and special fossil preservation. However, the core of the book centers strongly around the ten known (at 2009 publication) fossil specimens. It is in these pages that we find the world-class images of the Urvogel. 


Archaeopteryx; The Icon of Evolution. Peter Wellnhofer
The Berlin Specimen
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
If that wasn’t enough, Dr. Wellnhofer also accompanies his images with an extensive historical review of each acquisition, followed by a detailed and thorough examination of the fossils themselves. When I say detailed, I mean photographs taken under long-wavelength ultraviolet light, incredible close-ups using scanning electron microscopes and written descriptions of every skeletal element.

Archaeopteryx; The Icon of Evolution. Peter Wellnhofer
The Eichstatt Specimen
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
But don’t let these descriptions scare you. While there is a great deal of technical terminology in this book for any science buff, it is still easy to read and aimed at the general audience, like myself.  

If you are interested in this book, you probably already know that Archaeopteryx plays an important role, not only in the study of the origin of birds, but in the study of dinosaurs. Their fossils have been critical to our understanding of the theory of evolution. 

Its evolutionary relevance, which makes it the literal textbook example of a “missing link,” rests in the demonstrative mosaic distribution of plesiomorphic theropod features and derived avian ones (G. Mayr. 2017. Avian Evolution; The Fossil Record of Birds and its Paleobiological Significance.) 

I would like to now go over a few of those features, and little-known facts, with excerpts from the book. These are selected excerpts from my own notations that I hope will give you a good sense of what this book is all about. 

The London specimen sternum; 

“When I studied the specimen in June 1993, I came to the conclusion that the bony mass in question was nothing but three vertebrae in articulation encrusted by calcite, each 6.3mm long, presumably the last two cervicals and the first dorsal. Thus, all further conclusions of de Beer (1954) as well as the former speculations put forward by Petronievics and Smith-Woodward (1917) and Petronievics (1925) concerning the differences of the sterna in both the London and Berlin specimens, would collapse. This, however, is in total agreement with the fact that in none of the Archaeopteryx specimens was an ossified sternum present (Wellnhofer & Tischlinger 2004). It must be assumed that, at the time of death of the individuals, it was still cartilaginous and thus not fossilized, another evidence for their immature state of ontogenetic development.   

Feather study on the Berlin specimen; 

“Many details of the feathers can be studied on the counter slab much better than on the main slab. Lambrecht (1933) presumed that the reason for this preservational difference might be the repeated treatments of the main slab with organic and inorganic substances and hardeners during the numerous preparations and the procedures involved in producing casts. This has also made investigation under ultraviolet light difficult, since earlier coatings of the surface prevented fluorescence of bones and other structures. Lambrecht commented on this problem: “Today, the main slab of the Archaeornis is a real chemical laboratory in which most different precipitates were deposited. A removing of the dirty precipitations could not be considered because of the preciousness of the anyway tortured object” (Lambrecht 1933). The rather unspectacular counter slab of the Berlin specimen escaped this fate. Therefore, the finest structures of the feathers are preserved unaltered on this slab, rather than on the main slab. 

The right foot of the Munich specimen; 

“The right foot was flexed at the ankle to its maximum extent. With the first digit opposing the middle three, post-mortem flexion drew the toes into the semblance of a grasping or perching foot. So strong was the flexion that the claws of the first and fourth toe overlap. Even if this appears to be a position due to a contraction of ligaments and tendons after death, it shows clearly that a grasping and perching function was possible for Archaeopteryx in general. With respect to the stronger flexion of that leg at the knee joint, it might even have been possible in Archaeopteryx that flexion of the knee and the ankle caused a mechanically automatic flexion of the toes in order to grasp a branch or twig when resting on a tree, in the same way as in modern birds. 


Archaeopteryx; The Icon of Evolution. Peter Wellnhofer
The Munich Specimen
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
An unusual look at the Skull of the Thermopolis specimen;

“Along with the skulls of the Berlin and Eichstaat specimens, the skull of the Thermopolis specimen belongs to the three best preserved Archaeopteryx skulls found so far. It is the only one that displays its dorsal surface and exhibits details hitherto unknown. Both premaxillary bones are not co-ossified, not even in their most distal part at the front end, but have been separated due to post-mortem sedimentary pressure. The uncompressed snout forms a steep roof with a subtriangular cross section at an angle of 85 degrees. Following an elongated nasal opening, a small fenestra promaxillaris and a larger circular maxillary fenestra are present, suggesting a pneumatization of the antorbital sinus (Witmer 1990)”. 


Archaeopteryx; The Icon of Evolution. Peter Wellnhofer
The Thermopolis Specimen
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/

Interdental Plates 

“The presence of interdental plates appears to be a primitive archosaurian character (Wellnhofer 1993, Elzanowski & Wellnhofer 1996), since they are developed not only in most theropod dinosaurs (except for the Troodontidae), as in Megalosaurus, Dromaeosaurus and Ornitholestes, but also in many Triassic archosaurs like Euparkeria, crocodylomorphs and rauisuchians. In some theropods they are fused into a single bony “apron” which is regarded as a derived character, whereas separate, unfused plates are considered to represent the primitive condition (Currie 1987, Currie et al. 1990). Except for Archaeopteryx, in no other toothed bird are interdental plates known. They are an archaic (Plesiomorhous) character in the Solnhofen Urvogel”. 


Archaeopteryx; The Icon of Evolution. Peter Wellnhofer
Archaeopteryx interdental plates
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/

Glenoid Fossa

“The oval shoulder socket, fossa glenoidalis, for the articulation with the humerus, was located relatively high on the trunk and was laterally oriented. Anteriorly and posteriorly a bony rim (labrum) is developed allowing a greater elevation of the humerus, but also preventing the humerus from being taken closer to the body (Jenkins 1993). The lateral orientation of the glenoid fossa in Archaeopteryx is intermediate between the latero-ventral orientation in theropods and its latero-dorsal direction in modern flying birds. 


Archaeopteryx; The Icon of Evolution. Peter Wellnhofer
Archaeopteryx glenoid fossa
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/

The placement of feathers 

“The long humerus is devoid of feathers, tertiary remiges. This suggests that there was a gap in the plumage between the inner wing (secondaries) and the body, as is shown quite nicely in the life restorations of Archaeopteryx. 

“The long, feathered, bony tail of Archaeopteryx is primitive in contrast to modern birds, emphasizing once more its intermediate evolutionary state. A total of sixteen to seventeen pairs of rectrices are present, each pair related to a vertebral segment, leaving the proximal five to six caudals free of feathers (nine in the Munich specimen)”. 


Archaeopteryx; The Icon of Evolution. Peter Wellnhofer
Archaeopteryx feather placement
Photo Credit: Paul Cianfaglione
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“In the Berlin specimen, feathers on both sides of the right tibia, crural feathers, are preserved as impressions, indicating “breeches” similar to those of modern birds. They are also visible in the London and Eichstatt specimens. The individual feathers are about 25mm long and must have covered the entire leg, possibly as far down as the upper end of the metatarsus, rather than being arranged in a horizontal plane on both sides of the tibia”. 

As you can tell from the photos and information, this book is clearly a valuable resource for both researcher and layperson alike. I highly recommend this book.