Saturday, August 5, 2017

Avian Nectar Robbers


Last month, I had the pleasure of traveling to Ecuador for two weeks with my wife and three kids. We birded in delightful places such as the Cloud Forest near Mindo and the Amazon Rainforest along the Napo River. Sandwiched between our stays in Mindo and Napo, was a trek up into the Andes to a region known as the paramo. 

The paramo is an ecosystem described as being situated above the continuous forest line, yet below the permanent snowline. Even near the equator, morning temperatures can be very cold in the High-Andes, a sharp contrast from our other two Ecuadorian destinations.



The Paramo in Cotopaxi National Park, Ecuador
Photo Credit: Paul Cianfaglione

In addition to the sightings of Andean Condor (Vultur gryphus), the most remarkable birds present in the paramo were the hummingbirds. Situated at an elevation of over 11,000 feet, our hacienda featured a small selection of birds, mostly attracted to the grounds artificial plantings. Yet hummingbirds, which were one of only a few species to inhabit the property, were not encountered every day.



Hacienda Porvenir, Ecuador
Photo Credit: Paul Cianfaglione

A species of bird that we did encounter daily was the Black Flowerpiercer (Diglossa humeralis). Flowerpiercers have upturned bills with a hooked upper mandible and pointed lower mandible. As its name implies, the Black Flowerpiercer pierces the base of flowers with its unique bill and extracts the nectar through the hole with its brush-like tongue.

 
Black Flowerpiercer, Ecuador
Photo Credit: Paul Cianfaglione

A nectar robber, which the flowerpiercer clearly is, avoids contact with the floral reproductive structures, and therefore do not facilitate plant reproduction via pollination. Because many species that act as pollinators also act as nectar robbers, nectar robbing is considered to be a form of exploitation of plant-pollinator mutualism (Source: Wikipedia).

Pollination systems are mostly mutualistic, meaning that the plant benefits from the pollinator's transport of male gametes and the pollinator benefits from a reward, such as pollen or nectar. As nectar robbers receive the rewards without direct contact with the reproductive parts of the flower, their behavior is easily assumed to be cheating (Source: Wikipedia).

In the paramo, the sole focus of the Black Flowerpiercer was the shrub Datura, otherwise known as angel trumpet. Datura grows fast, upright, and often forms an umbrella-like canopy, under which huge 10-inch trumpet shaped flowers descend. The flower opening can easily be 5 inches wide.

 
Black Flowerpiercer and Datura Flower
Photo Credit: Paul Cianfaglione

Given the size of both the flowerpiercer and flower, it wasn’t unusual to observe the bird hard at work creating holes and feeding on nectar. What was unusual however was seeing those same flowers and holes being used for nectar extraction by one of the local hummingbirds.

 
Hummingbird Secondary Robbing a Datura Flower
Ecuador
Photo Credit: Paul Cianfaglione

Wow, this was very interesting! Did the hummingbird learn how to feed from the created holes (base of the flower) by watching the Black Flowerpiercers behavior? Had the hummingbird exploited the flower and flowerpiercer, and become a nectar robber itself?



Hummingbird Secondary Robbing a Datura Flower
Ecuador
Photo Credit: Paul Cianfaglione

In other Central and South American settings, flowerpiercers are known to be attacked by territorial hummingbirds defending their feeding areas. Did the paramos harsh environment and limited resources create a more mutualistic relationship between the two species?   

There are two main types of nectar robbing: primary robbing, which requires that the nectar forager perforates the floral tissues itself, and secondary robbing, which is foraging from a robbing hole created by a primary robber (Source: Wikipedia).


Hummingbird Secondary Robbing a Datura Flower
Ecuador
Photo Credit: Paul Cianfaglione
But there is a slight twist to this fascinating story. In an online paper published in 1994 titled Serrate Tomia: An Adaptation for Nectar Robbing in Hummingbirds? author Juan Francisco Ornelas suggests that some hummingbirds may in fact pierce the base of flowers themselves with their short, serrate, hooked bill.


Yes, some hummingbirds do have bill serrations, but those were thought to be more of a function to facilitate the holding of insect prey, rather than that of a cutting tool. As luck would have it, I also had the opportunity to observe a Black-throated Hermit (Phaethornis atrimentalis) hover and gorge on a hatching of flying insects during this very same trip.

Some hermits show bill serrations like Androdon, although less pronounced. These corresponding anatomical features between hermits and Androdon probably reflect convergent adaptations to spider-catching and not a common ancestry. https://www.researchgate.net/profile/Karl_L_Schuchmann/publication/275089338_Taxonomy_and_Biology_of_the_Tooth-billed_Hummingbird_Androdon_aequatorialis/links/5580128e08aec87640df2303/Taxonomy-and-Biology-of-the-Tooth-billed-Hummingbird-Androdon-aequatorialis.pdf

Even though the author points out some interesting morphological similarities between the bills of flowerpiercers and hummingbirds (serrated tomia), there seems to be little evidence, other than eyewitness accounts, that prove that hummingbirds make perforations at the base of flowers to extract nectar. Past observations may have been misinterpreted as primary robbing, instead of secondary robbing.

The paper also presents an alternative behavior (which I believe is more likely) of the mutualistic relationship of flowerpiercers and some hummingbirds. Here is what is generally known about this type of behavior;  

Since nectar robbing lets the nectar exploiter become essentially independent of floral morphology (Stiles 1985), some behavioral attributes should be associated with this behavior. For example, Stiles (1983) observed that Fiery-throated Hummingbirds (Panterpe insignis) utilize flowers perforated by flower-piercers and may follow the flower-piercer from flower to flower, using the flower-piercers' holes to extract the nectar. This observation suggests that an inherent difference in behavior should exist between this nectar robber and a non-nectar robbing species (Brian 1957). In contrast to most hummingbirds that visit flowers by the obvious and correct entrance, nectar robbers should be expected to have a more plastic and less stereotyped set of behaviors. In contrast to most legitimate visitors, nectar robbers need to keep track of the flowers that have been punc- tured by the flower-piercers and have to deal with, for example, flowers with well-protected nectaries such as most bromeliads. This suggests that nectar robbers should differ from legitimate visitors in their tenacity and observational skills when obtaining food. Another difference between these two groups of hummingbirds is that individuals of most nectar robbers forage alone, and rarely defend territories (Wetmore 1968, ffrench 1973, Meyer de Schauensee and Phelps 1978, Stiles 1985, Hilty and Brown 1986, Stiles and Skutch 1989). Typically, nectar robbers do not establish territories, but they are notably bellicose; they are able to withstand attacks of most territorial hummingbirds (Stiles 1985, Stiles and Skutch 1989).

Friday, June 30, 2017

Which extinct ducks could fly?


Copied from Science Daily, early bird news


Which extinct ducks could fly?

Date: June 7, 2017

Source:

American Ornithological Society Publications Office

We're all familiar with flightless birds: ostriches, emus, penguins -- and ducks? Ducks and geese, part of a bird family called the anatids, have been especially prone to becoming flightless over the course of evolutionary history. However, it can be difficult to determine from fossils whether an extinct anatid species could fly or not. A new study from The Auk: Ornithological Advances takes a fresh approach, classifying species as flightless or not based on how far their skeletal proportions deviate from the expected anatomy of a flying bird and offering a glimpse into the lives of these extinct waterfowl.



Fossils such as this partial skeleton of a Hawaiian species called Ptaiochen pau were used to determine whether extinct ducks and geese could fly.

Kyoto University's Junya Watanabe painstakingly measured 787 individual birds representing 103 modern duck and goose species. From this data, he developed a mathematical model that was able to separate flightless and flying species based on their wing and leg bones -- flightless species, the math confirmed, have relatively small wings and relatively large legs. Applying the model to fossil specimens from 16 extinct species identified 5 of the species as flightless, ranging from a land-dwelling duck from New Zealand to a South American duck that propelled itself underwater with its feet.

"I really enjoyed measuring bones in museums and appreciate the hospitality given to me by museum staff. One of the most exciting things was to find interesting fossils that were previously unidentified in museum drawers," says Watanabe. "What is interesting in fossil flightless anatids is their great diversity; they inhabited remote islands and continental margins, some of them were specialized for underwater diving and others for grazing, and some were rather gigantic while others were diminutive."

"Dr. Watanabe has developed a valuable statistical tool for evaluating whether a bird was capable of powered flight or not, based on measurements of the lengths of only four different long bones. His method at present applies to waterfowl, but it could be extended to other bird groups like the rails," according to Helen James, Curator of Birds at the Smithsonian Institution's National Museum of Natural History. "Other researchers will appreciate that he offers a way to assess limb proportions even in fossil species where the bones of individual birds have become disassociated from each other. Disassociation of skeletons in fossil sites has been a persistent barrier to these types of sophisticated statistical analyses, and Dr. Watanabe has taken an important step towards overcoming that problem."

Saturday, June 10, 2017

Stunning fossil reveals prehistoric baby bird caught in amber


Stunning fossil reveals prehistoric baby bird caught in amber

Copied to this blog from the Washington Post

By Ben Guarino June 9 at 6:00 AM 

Amber hunters in Burma dug up a remarkably complete bird hatchling that dates to the time of the dinosaurs. The bird's side, almost half of its body, was dipped in tree sap, which hardened around the neck bones, claws, a wing and its toothed jaws.

Scientists identified the animal as a member of the extinct group called enantiornithes, and published their discovery in the journal Gondwana Research this week.

The chick died young and fell into a pool of sap. It died halfway through its first feather molt, suggesting that the animal broke out of its egg just a few days before it perished. Its life began in the moist tropics beneath conifer trees. It ended near a puddle of conifer gunk, called resin, which fossilized into amber. Burmese diggers uncovered the amber 99 million years later.

The whole specimen is trapped in amber. (Lida Xing)

“Enantiornithines are close relatives to modern birds, and in general, they would have looked very similar. However, this group of birds still had teeth and claws on their wings,” said Ryan McKellar, a paleontologist at Canada's Royal Saskatchewan Museum. This animal lived during the Cretaceous Period, which came to a cataclysmic close 65.5 million years ago and took the non-bird dinosaurs with it.

The enantiornithes, due to their distinct hip and ankle bones, may have flown differently than modern birds. But they were capable fliers. (If you are wondering whether this bird relative was more bird or winged dinosaur, well, consider it both: Birds are avian dinosaurs, after all.)

Entombed in amber were details as fine as the hatchling's eyelid and the outer opening of its ear. The resin recorded no sign of a struggle. “The hatchling may have been dead by the time it entered” the resin pool, McKellar said. “One of the leg bones has been dragged away from its natural position, suggesting that the corpse may have been scavenged before it was covered by the next flow of resin.”

Evidence suggests that enantiornithes received little in the way of parental care, unlike more doting modern birds. The ancient chicks, born on the ground, had to scamper into trees to avoid being eaten. Scampering enantiornithes got stuck in resin fairly frequently, McKellar said, though this fossil is far more comprehensive than typical specimens.

Its 99-million-year-old claws appear almost as detailed as chicken feet you'd find in a supermarket. The foot, presumed at first to be a lizard's by the amber miner who found it, was covered in golden scales and just under an inch long. “The preserved skin surface allows us to observe the feet in great detail,” McKellar said.

The resin trapped one of the bird's wings as well. Despite its young age, the animal already had brown flight feathers on its wings. McKellar said it also had “a sparse coat of fluffy pale or white feathers across most of its belly, legs, and tail.”

McKellar and his colleagues probed the fossil using several types of imaging technology, including light microscopes and X-ray micro-CT scanning. The researchers discovered that the feathers on the enantiornithes' wings were quite similar to modern bird feathers. But its tail and legs were covered by what McKellar described as tufts similar to “proto-feathers” or “dino-fuzz.”

Recent amber discoveries offer strikingly detailed, if orange-tinted, windows into ancient worlds. Sap trapped not only birds but lizards, bugs and bits of non-bird dinosaurs, too. In December, McKellar and his colleagues announced they'd found a dinosaur tail trapped in amber also excavated from a mine in Burma (also known as Myanmar).

But amber containing dino DNA, as popularized by “Jurassic Park” and its ancient mosquitoes swollen with dinosaur blood, appears to remain in the realm of science fiction. “Unfortunately, DNA seems to be ‘off the menu’ for specimens such as this one,” McKellar said. “To the best of our current understanding, DNA has a half-life of around 500 years and cannot be recovered in meaningful quantities from amber pieces that are more than a few million years old.”

That doesn't mean amber completely erases prehistoric biochemistry. The scientists have teased iron from the toothed bird, trapped in carbon in the hatchling's soft tissues, possibly from its blood. Further research may uncover proteins from the bird's feathers, McKellar said, allowing experts to home in on the colors of the animal's brown plumage.

Wednesday, May 3, 2017

Eggshell Ornamentation and its primitive condition

A couple years ago, I had the pleasure of going behind the scenes of the Yale Peabody Museums Ornithology and Paleontology collection departments. It was an amazing experience, chock full of surprises such as seeing the original killer claw of Deinonychus antirrhopus, a treasure trove of dinosaur fossils from the late 19th century “Bone Wars” as well as drawers filled with colorful birds from around the world.    


But as I was leaving the Ornithology Department, my eyes caught sight of a tray full of various sized bird eggs. I asked the curator about the assemblage of eggs and he mentioned that they were going to be part of a new exhibit at the museum called Tiny Titans: Dinosaur Eggs and Babies.

 
Bird Egg Display
Yale Peabody Museum
Photo Credit: Paul Cianfaglione
Before departing, I asked the curator one more question, pointing to a black, glossy egg situated near the center of the tray. Who does this egg belong to? A tinamou egg he replied. I bent down for a closer look and said to myself, this is crazy, it looks so fake. How on earth did a bird end up evolving an eggshell that looks like glass?

I returned to the museum a few weeks later for the exhibit. Not only did I want to see the tinamou egg again, but I was also curious about the theropod eggs that were slated to be on display.

Most of the fossil eggs featured in the exhibit were real, an unexpected treat! What struck me the most about the dinosaur eggs was how coarse the outer eggshells were. As I examined the fossils, I thought to myself, how did eggs go from being so utterly prehistoric looking, to completely polished?

Fossil dinosaur eggs often show various sculpture patterns, but the function of this ornamentation is not clearly understood at this point, in part because modern eggs do not show the same patterns; most modern eggshell has a relatively smooth external surface.

I left the museum that day with a desire to learn more about the evolution of eggshell ornamentation over time, from bird-like theropods during the Cretaceous Period, to Paleogene birds, to today’s species. Were theropod eggs and bird eggs really that similar, as the exhibit implied?

One of the best places to begin our investigation is in Luis Chiappe’s excellent book, Glorified Dinosaurs, The Origin and Early Evolution of Birds (2009). It was here in this book that I distinctly remember seeing a diagram laying out the characteristics of the eggs of several lineages of non-avian dinosaurs and birds. We all know about the numerous skeletal features that support the inclusion of birds within theropod dinosaurs, but could eggshells also help support it?   

The diagram shows crocodile, sauropod, oviraptorid, troodontid and bird eggs. One layer shells for crocodiles and sauropods, two layer in the oviraptorid and troodontid and three for birds. Chiappe goes on to write about two-layered eggs of theropods;

In oviraptorid eggs; as with the eggs of crocodiles and birds, the shell of this egg was composed of a variety of calcium carbonate called calcite. However, detailed comparisons between the shell microstructure of this egg and those of extant crocodiles and birds revealed features uniquely shared with bird eggs. The most obvious of these was the fact that the calcite crystals comprising the eggshell were laid in two distinct layers, rather than the single layer they form in the eggshell of crocodiles. The crystalline structure of the innermost layer of both oviraptorid egg and avian eggs is formed by elongate crystals that radiate from a core. This inner layer is thought to be homologous to the single layer of calcium carbonate that forms the shell of the eggs of crocodiles, sauropods and ornithischian dinosaurs. The second layer overlaying the innermost layer of the oviraptorid egg has a contrasting manifestation, its crystals are arranged in such a way that when thin sections of the eggshell are viewed under a microscope, the entire second layer has a laminated, plywood-like appearance. Avian eggs also exhibit a layer of similar appearance over their innermost layer of calcite, even in modern birds this layer may grade into or be completely separated from a third layer.

 
Citipati osmolskae
Image Credit: Peter Shouten
With paid permission

In troodontids; eggs of the lightly built troodontids also show the asymmetric shape characteristic of the eggs of birds, in which one pole of the egg is distinctly narrower than the other. But the existence of more than one distinctive layer in the eggshell and the asymmetry exhibited by the troodontid eggs are not the only features in common between the eggs of non-avian theropods and birds. These animals also evolved eggs with fewer pores (the airholes that pierce the eggshell), an elongate shape, and a proportionally bigger volume in relation to the size of the adult. All these similarities between the eggs of non-avian theropods and birds suggest the dinosaur predecessors of birds had already evolved the complex cellular and glandular process that control the unique attributes of the avian egg.

This is certainly important to understand, and at the moment, confirmed my earlier suspicions about the primitive nature of the two-layered, coarse dinosaur egg.  

The exhibit at the Peabody Museum displayed a number of oviraptorid eggs. The eggs of most interest to me were the ones from the Nanxiong Basin in Guandong China. These were the type of oviraptorid eggs that I was fortunate to have studied and photographed myself. I concluded, based on the coarse ornamentation, that the eggs I examined belonged to a fossil egg genus called Macroolithus.

 
Macroolithus eggshell
Photo Credit: Paul Cianfaglione
Macroolithus is an oogenus (fossil-egg genus) of dinosaur egg belonging to the oofamily Elongatoolithidae. The type oospecies, M. rugustus, was originally described under the now-defunct oogenus name Oolithes. Three other oospecies are known: M. yaotunensis, M. mutabilis, and M. lashuyuanensis. They are relatively large, elongated eggs with a two-layered eggshell. Their nests consist of large, concentric rings of paired eggs. There is evidence of blue-green pigmentation in its shell, which may have helped camouflage the nests (Source: Wikipedia).

Macroolithus eggs are characterized by large size, measuring 16 to 21 cm (6.3 to 8.3 in) long, and by their particularly coarse ornamentation.

(Note: The eggs I photographed below measure 7 ¼ inches long x 3 ½ inches wide)

 
Oviraptorid Eggs
Photo credit: Paul Cianfaglione
This made me wonder, did all theropod dinosaur and Mesozoic bird eggs preserve similar coarse ornamentation? The answer was a surprising no. In a recent paper titled; Reproduction in Mesozoic birds and evolution of the modern avian reproductive mode (Varricchio and Jackson 2016), researchers provide a simplified phylogeny showing hypothesized stages in the evolution of reproductive traits toward modern birds.


Listed within the five stages of evolution are the troodontids, which have stage 3 eggs that clearly lack surface ornamentation. Stage 4 enantiornithine birds, a group of extinct avialans, are recognized on the basis of their overall shape, lack of eggshell ornamentation, and microstructure. All these Mesozoic creatures have eggs with smooth external surfaces, with the exception of one, which bear micronobbules.

simplified phylogeny showing hypothesized stages in the evolution of reproductive traits toward modern birds
Image Credit: Varricchio and Jackson 2016  

This was again interesting information, especially with the concept of a smoother eggshell now existing deeper in time. The researchers also mentioned an increasing occurrence of a third layer in eggs of enantiornithines (Schweitzer et al. 2002, Balanoff et al. 2008) and in eggs that are likely of Cretaceous non-avian maniraptoran theropods (Bonde et al. 2008, Jackson et al. 2010, Agnolin et al. 2012). This suggests that a number of traits (including a smoother eggshell) had an earlier origin than in modern birds (Schweitzer et al. 2002, Jackson et al. 2010)”.

 
Troodontid Smooth Eggshell (A)
Image Credit: http://www.ucmp.berkeley.edu/science/eggshell/eggshell2.php

Could my ideas concerning the primitive condition of dinosaur and bird eggs now be in limbo? Should we anticipate a future discovery of a smoother-shelled egg older than a troodontid to be on the horizon? Remember, birds are dinosaurs, and crocodilians are the closet living relatives to the Dinosauria as a whole. If both birds and crocodilians share a particular feature, then there’s a chance that a smoother eggshell was present in basal theropods, too.

But what if we throw a monkey-wrench into all this dialogue about eggshells. In an unprecedented discovery, our previously mentioned researchers who specialize in the study of fossil eggs, describe a 35 million-year-old egg from Nebraska which bore a strong resemblance to a non-avian theropods egg, with tiny lumps and waves that she and her team describe as an “undulating ornamentation”.


“If it had been discovered in the Cretaceous layer, dating from 66 million to 145 million-years-ago, you would likely think it was that of a theropod dinosaur rather than a bird; it has more characteristics of the former than the latter,” she said in an interview.

The fossil is so unusual that it appears to be a type of egg that’s entirely new to science, she said.

Indeed, Jackson and her colleagues say the egg is likely evidence of an ancient bird with some unexpectedly dinosaur-like traits — one whose reproductive features, at least, reveal the piecemeal transition by which two-legged dinosaurs evolved into modern birds. (Disclaimer; I have not read the paper nor seen a picture of this supposed egg).   

How do you explain this discovery? Perhaps like this; paleognathous birds, like the extant emu, also retain some basal morphological characters. One of those characters appears to include the eggshell surface. Under a microscope, one can see ornamentation with obvious peaks and valleys, similar to the discussed oviraptorid eggs.

 
Emu Eggshell Ornamentation
Photo Credit: Paul Cianfaglione

What benefits does a coarse eggshell provide an animal anyway? Rolling resistance? If that was the case, today’s cliff-nesting Common Murres, in addition to featuring very asymmetric eggs, should have shown some signs of granular eggshell ornamentation. How about for strength and protection? Like the exoskeleton of an arthropod or crustacean, the thick, coarse integument would have made it more difficult for a predator bearing serrated teeth to puncture and crush an eggshell.    

There is certainly more to the evolution of dinosaur and bird eggs than just the appearance and disappearance of surface ornamentation. Size, asymmetry, porosity and external layers all still place the oviraptorid egg, as we still know it, as the primitive condition toward birds.

However, as more and more fossil eggs are being discovered, it’s becoming clear, that the traits once thought to be unique to birds, or unique to non-avian dinosaurs, may no longer apply. This includes eggshell ornamentation.

Thursday, April 6, 2017

Eoconfuciusornis: The Most Well Preserved Fossil Bird


Date: March 24, 2017

Source: Science Daily


In a new paper published in National Science Review, a team of scientists from the Institute of Vertebrate Paleontology and Paleoanthropology, the Shandong Tianyu Museum of Nature, and the Nanjing Institute of Geology and Paleontology (all in China) described the most exceptionally preserved fossil bird discovered to date.

The new specimen from the rich Early Cretaceous Jehol Biota (approximately 131 to 120 million years old) is referred to as Eoconfuciusornis, the oldest and most primitive member of the Confuciusornithiformes, a group of early birds characterized by the first occurrence of an avian beak. Its younger relative Confuciusornis is known from thousands of specimens but this is only the second specimen of Eoconfuciusornis found. This species comes only from the 130.7 Ma Huajiying Formation deposits in Hebei, which preserves the second oldest known fossil birds. Birds from this layer are very rare.

This new specimen of Eoconfuciusornis, housed in the Shandong Tianyu Museum of Nature, in Eastern China, is a female. The ovary reveals developing yolks that vary in size, similar to living birds. This suggests that confuciusornithiforms evolved a period of rapid yolk deposition prior to egg-laying (crocodilians, which are archosaurs like birds, deposit yolks slowly in all eggs for months with no period of rapid yolk formation), which is indicative of complex energetic profiles similar to those observed in birds.



Photo Credit
https://academic.oup.com/nsr/article/3052674/Exceptional

This means Eoconfuciusornis and its kin, like living birds, was able to cope with extremely high metabolic demands during early growth and reproduction (whereas energetic demands in crocodiles are even, lacking complexity). In contrast, other Cretaceous birds including the more advanced group the Enantiornithes appear to have lower metabolic rates and have required less energy similar to crocodilians and non-avian dinosaurs (their developing yolks show little size disparity indicating no strong peak in energy associated with reproduction, and much simpler energetic profiles, limited by simpler physiologies).

Traces of skin indicate that the wing was supplemented by flaps of skin called patagia. Living birds have numerous wing patagia that help the bird to fly. This fossil helps show how bird wings evolved. The propatagium (the flap of skin that connects the shoulder and wrist) and postpatagium (the flap of skin that extends off the back of the hand and ulna) evolved before the alular patagium (the flap of skin connecting the first digit to the rest of the hand), which is absent in Eoconfuciusornis. Even more unique is the preservation of the internal structure of the propatagium which reveal a collagenous network identical to that in living birds. This internal network gives the skin flap its shape, allowing it to generate aerodynamic lift and aid the bird in flight.

The nearly complete plumage preserves remnants of the original plumage pattern, revealing the presence of spots on the wings and the earliest documentation of sexual differences in plumage within birds. This new specimen suggests that female Eoconfuciusornis were smaller than males and lacked tail feathers, similar to many sexually dimorphic living birds and the younger Confuciusornis in which the plumage of the males and females are different from each other. Samples of the feathers viewed under a microscope reveal differences in color characteristics, allowing scientists to reconstruct the plumage. Female Eoconfuciusornis had black spotted wings and gray body with a red throat patch.

Researchers have not found fossils from any other bird from the Jehol period that reveal so many types of soft tissue (feathers, skin, collagen, ovarian follicles). These remains allow researchers to create the most accurate reconstruction of a primitive early bird (or dinosaur) to date. This information provides better understanding of flight function in the primitive confuciusornithiforms and of the evolution of advanced flight features within birds.

"This new fossil is incredible," said co-author Dr. Jingmai O'Connor. "With the amount of information, we can glean from this specimen we can really bring this ancient species to life. We can understand how it grew, flew, reproduced, and what it looked like. Fossils like this one from the Jehol Biota continue to revolutionize our understanding of early birds."

Tuesday, March 28, 2017

"Naked Birds"; how people see and value avian life



I've been involved in one way or another with birds my whole life. Birdwatching, education, conservation projects, bird sanctuary manager, travel; you name it, I’ve had my hands in it.

Today, my interests in birds lie mainly in their origin and evolution. But this hasn’t stopped me from keeping abreast of present-day issues related to birds.

So, when I hear people out in the field talk about birds, or write questionable comments on the internet with regards to them, my ears quickly prick up.

One of those comments was the inspiration for today’s blog posting.

Recently, a series of photos were posted to Facebook showing a European Starling being pinned down under the talons of a Sharp-shinned Hawk. They were grisly images of a struggling starling being slowly eaten alive by a hawk. Before posting, the photographer was kind enough to warn people about the graphic nature of the images, but also went out of his way to assure people that it was O.K for this to be happening, since the starling is an invasive species and needs to be controlled. In many minds, the less we have of this aggressive bird, the better off we are.

 
European Starling
Photo Credit: Paul Cianfaglione

My own reaction to the Facebook post was pretty much middle-of-the-road. I fully understood the photographers position, as well as anyone else who may have felt saddened over the starling’s loss. People value certain birds over others for various reasons. Native versus introduced, beauty over ordinary, rare as opposed to commonplace.

As I just mentioned, putting a price tag on a bird’s head is highly subjective. But what if I told you that I think every bird is deeply the same, would you be surprised? Could you ever accept the fact that the starling is just as valuable to our world as a Scarlet Tanager?? Let me then ask you this, have you ever admired a bird for something other than its flamboyant plumage? By concentrating on appearance alone, we sometimes lose sight of the fundamental characteristics of birds.

Before I attempt to open your mind to these seemingly ridiculous claims, let’s put ourselves into a hypothetical situation. You are in a Natural History Museum, in front of a display case. In it are two birds perched on a faux branch, one is a European Starling, the other is our Scarlet Tanager. At once, your eyes gravitate toward the more esthetically pleasing tanager. Its brilliant red plumage, combined with black wings and bill, jump out and pull you in for a closer look. You read its placard and discover it’s a neo-tropical migrant, and nests nearby at a favorite state park. The tanager draws a momentary pause of admiration and awe. 


Scarlet Tanager
Photo Credit: Wikipedia
The starling placard on the other hand reads; set loose in New York's Central Park in the early 1890s, commonly found in cities, aggressive toward native birds, often displacing them from natural nest cavities. Compared to the tanager, not a flattering description. No wonder birders often refer to starlings as “feathered rats”.

But what if we take that same situation, turn it around, and remove each and every feather from the two birds. No placards. How would you react? Do your eyes now drift over to the starling’s long yellow bill, heavily armored feet and larger size? Does its size and adornments in any way distract you from the unimpressive featherless tanager?  

Bird Mummy
Scarlet Tanager
Photo Credit: Paul Cianfaglione
In a weird way, the two birds now look somewhat similar. No more distinctively colored plumage, no defining field marks, missing tail feathers and truly bald head. Gone are the pre-misconceptions.

If this type of “naked” bird exhibit ever did come to fruition, there would certainly be some backlash from the general public.

In fact, there were some strong views recently posted to the internet when a Twitter user dug up and decided to share “naked” Barn Owl images with the rest of the world.

Featherless Barn Owl
Photo Credit:http://sarcasmsociety.com

"I just googled what owls look like without feathers and I am severely shook," a person wrote.

Another was quoted as saying; we're sure she was 'shook,' because as it turns out, beneath those lovely feathers lies a demon hell-bird with black, soulless eyes that can show you how you'll die years before it actually happens (end quote).

It’s actually very easy to forgive people for such strong resentment, bird lovers are not use to seeing their favorite wood warbler plucked clean like a supermarket chicken.

But if we take a more scientific approach to these shocking images, we may start to see and value birds, even the more deplorable ones, a bit more differently.

For this, I’d like to turn to one of my favorite books by Gary Kaiser called; The Inner Bird, Anatomy and Evolution. In it, Kaiser nicely describes what we should be thinking about if confronted with an image, or display case filled with “naked” birds. Remember, the evolutionary success of birds comes down to its bodies highly centralized structure. Kaiser writes;

Although the outer cloak of feathers is an important part of the animal, all living functions are the responsibility of the inner bird. The inner bird is a strange goblin-like creature that manipulates its appendages by pulling on long tendons just as the human operator within the muppet Big Bird pulls on a network of internal wires and strings. The puppeteer gets to enjoy an independent existence when he sheds his casing at the end of the workday, but the plumage of the inner bird is part of an integrated whole animal.

Suggesting that we should look at the inner bird as a puppeteer behind a screen of feathers may seem an extreme point of view but it does not overstate the case. The muppet analogy extends beyond the feathered suit to the bird’s basic design. In mammals, the limbs are moved by muscles that are distributed over the whole skeleton so that they lie close to the joints they move. There is ample additional room on the limbs for generous blood supplies and even stores of fat.

In birds, the muscles are remote from the joints and the limbs often appear thin and sticklike. Even the fleshier wings are little more than nubs, with no more tissue than is needed to carry and manipulate the feathers during flight. The limbs are not one of the places where a bird can store its reserves of fat, and they offer little space for blood vessels or nerves. Because the muscles are collected together in a dense mass and anchored as close as possible to the body’s core, they often lie far from their point of action and depend on long tendons to carry out their responsibilities. Tendons from muscles along the breastbone move the wing, while others along the backbone move the tail. Even the muscles that curl the toes are mounted high on the leg.

Though we can’t see the tendons, blood vessels and nerves under the skin, we can certainly see the centralized structure that characterizes the inner-bird strategy for flight.

For those who seek a greater meaning to a bird’s existence than just field marks and conservation issues, featherless images may be what is finally needed to strike a chord in one’s mind.

 
Featherless Lovebird
Photo Credit:https://www.buzzfeed.com/laurenstrapagiel/naked-bird
Stripped of feathers and pre-misconceptions, and back on a level playing field, the European Starling, Brown-headed Cowbird and Mute Swan are no longer invasive species, parasites or eye sores, but are instead viewed as 150 million-year-old evolutionary success stories.   

The scientific consensus at this time is that birds are a group of theropod dinosaurs that evolved during the Mesozoic Era. Because beneath the feathers, beneath the skin, birds share many unique skeletal features with dinosaurs including the neck, pubis, wrist (semi-lunate carpal), arm and pectoral girdle, shoulder blade, clavicle, and breast bone. Non-avian dinosaurs were even feathered.

Finally, I would like to say a few words about invasive species. I do not advocate at all the introduction of exotic animals into non-native habitats. In a world where forests, fields and wetlands are being lost at an uncontrollable rate, these exotic animals only make life tougher for native birds and conservationists alike. The pre-misconceptions I alluded to about the European Starling was not to ignore the problems they cause, but to simply recognize the bird for what it is; a survivor in life’s race.

Wednesday, March 15, 2017

Fossil Birds of China, A pictorial book review



Have you ever known about, or wanted a particular book, but never got around to buying it? It just sits there in the back of your mind, returning again and again for serious consideration, until you finally purchase it some years later. That’s exactly how I acquired my latest out-of-print book called, Fossil Birds of China.

Fossil Birds of China, Book
Photo Credit: Paul Cianfaglione
Published in 2003 in both Chinese and English, Chief Compiler Hou Lianhai puts together a well-organized look (234 pages) at the early stages of fossil bird discovery in China. It’s a fairly large paperback book measuring in at 280x210 mm, made of high quality, thick paper stock.

The contents of this book include reconstructions of 53 fossil birds, classified as Archaeornithes, Enantiornithes and Ornithurae. Each one is represented in full color by its original fossil holotype, skeletal drawing and life painting.

 
Eoenantiornis buhleri
Fossil Birds of China
Photo Credit: Paul Cianfaglione

In addition to the fossils and incredible paleoart, the book provides pertinent information to go along with its discovery. This includes its scientific name, etymology, locality, preservation and diagnosis.

The diagnosis was easy to understand and interesting to me, something you don’t get in every bird evolution book. In contrast to long-worded scientific papers, the Fossil Birds of China provides a concise and welcome account of the most important and obvious skeletal features. For instance, the diagnosis for Sinornis santensis reads like this; Medium sized bird. Rostrum short. Teeth and pelvis similar to that of Archaeopteryx. Gastralia present. Second digit twice as wide as first digit. Digit 1 reduced. Small and curved claws present on digits 1 and 2. Tarsometatarsus fused proximally. Pygostyle present.

 
Sinornis santensis
Fossil Birds of China
Photo Credit: Paul Cianfaglione
However, not all information in this book is correct. The description of Confuciusornis dui states that its teeth on the lower jaw differ from that of Confuciusornis sanctus. Did Confuciusornis sanctus have teeth? Of course not, and neither did Confuciusornis dui. But C. dui did differ in smaller adult size and had an upturned bill tip (mentioned), indicative of a unique diet.

Confuciusornis sanctus
Fossil Birds of China
Photo Credit: Paul Cianfaglione
It’s easy to forgive such inaccuracies with past fossil interpretations. Even today, I’m currently reading a paper titled, Taxonomical Reappraisal of Cathayornithidae (Aves: Enantiornithes) Min Wang and Di Liu (2015). In the reappraisal, researchers point out that the unfused pygostyle originally described in the holotype of Cathayornis, was instead its partial left femur.

 
Cathayornis yandica
Fossil Birds of China
Photo Credit: Paul Cianfaglione
The artistic reconstruction of early birds in Fossil Birds of China is second-to-none. Both Anderson Yang and Zeng Xiaolian help bring the fossils back to life in colorful, yet believable and in tastefully done settings. Despite the limited amount of information available, and their lack of paleontological training, the artists did an extraordinary job painting the birds and environment as it existed 130 million-years-ago.

Imaginative at times, researchers and artists place Jibeinia luanhera, with its Blue Jay colored tail, high in a tree nest, despite any evidence of this occurring during the Mesozoic.


Jibeinia luanhera
Fossil Birds of China
Photo Credit: Paul Cianfaglione
Like Jibeinia’s tail, there were other ancient birds with colors reminiscent of today’s extant species. Confuciusornis chuonzhous was a dead ringer for North Americas Greater Roadrunner, while Longipteryx chaoyangensis was identical to the Eurasian (Common) Kingfisher.   

 
Confuciusornis chuonzhous
Fossil Birds of China
Photo Credit: Paul Cianfaglione
The Fossil Birds of China also has a wonderful section on Paleogene bird fossils. This was the first time I realized that extinct giant bird Diatrymiformes were found in Asia, plus a host of the other earliest relatives of today’s birds. Many of the species are represented and identified by a single bone.

I highly recommend this book on two accounts. First, found in this book are the clear, close-up images of fossil holotypes, which are sometimes hard to come by, even on the internet. Except for Luis Chiappe’s book Glorified Dinosaurs (2009) and Birds of Stone (2016), most fossil images are unsatisfactorily set on averaged sized pages. This was a nice feature of the book.

The second is the paleoart. I’m not saying that all of the paintings are accurate portrayals of the species, but they do let one’s imagination run wild, giving the reader an opportunity to pass their own judgements about how ancient birds looked and lived.  

 
Boluochia zhengi
Fossil Birds of China
Photo Credit: Paul Cianfaglione
The Fossil Birds of China is a nostalgic look at the beginnings, of what has turned out to be, a treasure trove of continued scientific discovery. If you can find it, buy it!


Largirostrornis sexdentornis
Fossil Birds of China
Photo Credit: Paul Cianfaglione