Saturday, December 30, 2017

Ichnology of New England by Edward Hitchcock, 1858

The end of July can be a very dry time of year in Connecticut. So dry, that in severe drought conditions, the Connecticut River will often reveal much of its soft sedimentary shores. When this happens, I like to turn my attention to the tracking of birds, rather than simply watching their behavior.

The tracks and trails left behind by birds are known as trace marks, so named because they preserve the only evidence of an animal’s occurrence and behavior, without seeing the birds themselves. Neoichnology is the study of modern traces.

The most common birds along the river include the Killdeer, Spotted Sandpiper and Great Blue Heron. On some occasions, a land bird will venture out to the river’s edge, leaving behind their rarely seen footprints. This often makes bird track interpretation a major challenge.  

The type and quality of a trace mark left behind by birds depends on its body structure, but it also depends on the condition of the sediment.

The footprints on the left (photo below) clearly shows the birds toe shape on the underside of its foot, whereas the tracks on the right become increasingly less distinct as the bird steps into softer sediments.

Shorebird tracks in mud
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
In my neck-of-the-woods, tracks are a popular attraction. Not the type of tracks I was just referring to, but dinosaur tracks. Less than two-miles away from where I stand lies an 11,000-square foot area of exposed bedrock containing some 600 tracks, preserved in red and gray sandstone that served as a lake shoreline 200 million-years-ago.

The world-class exposure of Early Jurassic dinosaur trackways at Dinosaur State Park in Rocky Hill, Connecticut have drawn eager visitors from the youngest schoolchildren to renowned research scientists. One of those scientists was the late John Ostrom from the Yale Peabody Museum, who was on hand, and instrumental in preserving the trackway during its initial discovery in 1966.

Dinosaur State Park, Rocky Hill, Connecticut
http://avianmusing.blogspot.com/
John Ostrom (February 18, 1928 – July 16, 2005) was an American paleontologist who revolutionized our modern understanding of dinosaurs in the 1960s, showing that dinosaurs were more like big non-flying birds than they were like lizards (ref. Wikipedia).

Ostrom described many similarities between theropod dinosaurs and birds such as the semi-lunate carpal bone of the wrist, reduction of digits on their hands, hollow bones, wishbone and many others. Even their tracks are similar, like the ones on display at Dinosaur State Park.

So similar in fact that even experts in the field of fossil track interpretation have trouble distinguishing small theropod tracks and birds.

Two of those experts, Martin Lockley and E. Rainforth, attempt to outline these differences in a fairly recent article titled “The Track Record of Mesozoic Birds and Pterosaurs; An Ichnological and Paleoecological Perspective” (Mesozoic Birds; Above the head of Dinosaurs, 2002; pp 405-418).

Lockley and Rainforth describe their methods below on how to identify the tracks of birds and how not to confuse them with the pes tracks of non-avian dinosaurs; the following criteria are useful, although not foolproof, in determining whether tracks were made by birds or other track makers, but, given that almost all fossil bird are those of water birds, it is to this group that these criteria apply: (1) general resemblance to the tracks of neornithines (modern birds); (2) small size; (3) slender digit impressions with indistinct differentiation of the pad impressions; (4) wide divarication angle, approximately 110-120 degrees between the outer digits; (5) caudally directed hallux (digit 1), oriented up to 180 degrees from middle forward digit; (6) slender claws; and (7) claws on the outer digits curving distally away from the middle digit.
Dinosaur and bird track measurements
Xing et al. 2014
http://avianmusing.blogspot.com/

Smaller theropods also make relatively long and narrow digit impressions, ending in sharp claw marks. However, theropod digits are often held closely together in a V-shape, with well-defined toe pads, like the track pictured below.

Anchisauripus fossil track
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
But the study of bird and dinosaur tracks (ichnology) is no recent phenomenon. In fact, here in the northeastern part of the United States, it can be traced (no pun intended!) all the way back to the year 1858 with the publication of the book; Ichnology of New England: A Report on the Sandstone of the Connecticut Valley, by the Reverend Edward Hitchcock.


Ichnology of New England 1858
Edward Hitchcock
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/

Hitchcock was a paleontological paradox, the first Director of the Massachusetts Geological Survey, President of Amherst College and the most influential Congregational pastor and theologian in the first half of the 19th century.

Edward Hitchcock
Image Credit: William S. Tyler
avianmusing.blogspot.com/
The earliest and in many ways the best mind in dinosaur science, he was a fervent anti-evolutionist and never used the term “dinosaur,” not even in the late 1850’s. (Bakker, R. 2004. “Dinosaurs Acting Like Birds, and Vice Versa – An Homage to the Reverend Edward Hitchcock, First Director of the Massachusetts Geological Survey” in Feathered Dragons).

He published papers on fossilized tracks in the Connecticut Valley, including Eubrontes and Otozoum, that were later associated with dinosaurs, though he believed, with a certain intuition, that they were made by gigantic ancient birds.


Provided what is known today about the evolution of birds, which most scientists now believe birds are the direct descendants of one group of coelurosaurian dinosaurs, it’s easy to sit back and second guess Hitchcock’s 160-year-old interpretations, or his place in scientific history.

Some say that Hitchcock was right all along, while others say he was flat out wrong for not recognizing the tracks as dinosaurian.

Brian Switek, a freelance science writer specializing in evolution, paleontology, and natural history, is one who has recently questioned why Hitchcock insisted that birds left the footprints. (Switek, B. 2011. Hitchcock’s Primeval Birds).


He writes;

“Perhaps his obstinacy prevented him from accepting new ideas during a critical period of change within geology, paleontology and natural history. We may never know. Unless a letter or journal entry articulating his thoughts on the subject appear, his anti-dinosaur interpretation will remain a mystery”.

This may be true, but I believe Hitchcock simply couldn’t get past the fossil tracks resemblances to modern day birds. New scientific theories were acknowledged, but for the moment, emotionally overridden.

Remember, Hitchcock’s first impression of the tracks ploughed up in South Hadley, Massachusetts in 1802 were that of “poultry”, “a turkey tribe” or of Noah’s Raven”.

By the time he was finishing up his 1858 Ichnology of New England monograph, Hitchcock had before himself an incredible portfolio of both thick-toed specimens and narrow-toed specimens to compare and garner information from.
Edward Hitchcock fossil tracks
Beneski Museum of Natural History
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
Edward Hitchcock fossil tracks
Beneski Museum of Natural History
Photo Credit: Paul Cianfaglione
avianmusing.blogspot.com/
The narrow-toed specimens included Argozoum, Platyterna, Ornithopus and Tridentipes; smaller tracks which were mirror images of birds found combing around the yard of the Reverends Massachusetts home. He even compared the ancient tracks made by the chicken-size dinosaur Corvipes lacertoideus to the snow-bird Fringilla hudsonia, which appear to both possess long toes that run directly backwards.

Corvipes lacertoideus tracks (upper left)
Ichnology of New England 1858
Edward Hitchcock
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/


Hitchcock’s method in track study is also laid out in his monograph, under the heading; Characters that are constant and distinctive in the feet of animals, and in their mode of progression. Some of these characters include the number of toes, absolute and relative length of the toes, divarication of the lateral toes, divarication of the inner and middle toes, relative length of the middle toe, number and length of the phalanges, character of the heel, angle between the axis of the foot and the line of direction, etc.

As I mention earlier in the post, todays foremost experts in the field of fossil track identification still employ many of the same methods used by Hitchcock 160 years ago, with basically the same results.

At this point, it is easy to understand how Hitchcock could turn-around and suggest an avian affinity for the larger three-toed, thick-padded tracks.

Brontozoum tracks
Ichnology of New England 1858
Edward Hitchcock
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
His views were further supported by the discovery of the extinct Moa, an enormous flightless bird which Richard Owen described in 1839 by a single thigh bone. Additional fossil Moa material soon confirmed Owen’s premonition. When the news reached Hitchcock in 1843 about the ancient bird, he was overjoyed.

Megalapteryx (moa) foot
Photo Credit: Wikimedia Commons
http://avianmusing.blogspot.com/

He goes on to write confidently about the thick-toed specimens resemblances to large flightless birds in his 1858 Ichnology of New England monograph;

The alternation of right and left feet, proves the animals to have been bipeds. The number and position of the toes ally them to certain kinds of birds, namely, the Scansores and Grallatores. The first order embraces the ostrich tribe; namely, the African Ostrich, the Cassowary, or New Holland Ostrich, and the Rhea, or South American Ostrich, as well as the extinct species of Aepiornis, Dinornis, and Palapteryx of Madagascar and New Zealand. It is to these fossil species that the Brontozoum and Amblonyx seem most nearly related. In order to show this, I give a representation, of a small size, of the foot of Palapteryx ingens, as figured by the late Gideon Mantell, from a very perfect specimen. The ungual phalanx in this specimen looks much like a claw, and indeed, we can sometimes determine with difficulty where the claw ends and the bone begins. At any rate, when the two outer phalanges were bound together by ligaments and covered by integuments, they and the claw would make only two impressions, namely, that of a phalanx and of a claw.

Hence the whole track of the Palapteryx would exhibit two phalanges on the inner toe, three on the middle and four on the outer, each terminated by a claw. And this is a general law as to the feet of living birds. Those which have a fourth toe inside, show on that toe only one phalanx besides the ungual and a claw.

Why did Hitchcock insist that birds left the footprints? There is one additional bit of information that needs to be noted here. Famed paleontologist Robert T. Bakker provides another possible answer in the introduction to the book Feathered Dragons (2004), “Dinosaurs Acting Like Birds, and Vice Versa – An Homage to the Reverend Edward Hitchcock, First Director of the Massachusetts Geological Survey”.

Yes, indeed, Hitchcock never used the word “dinosaur” when discussing his beloved bird-tracks. But that was not because he was a naïve paleo-bumpkin. Hitchcock didn’t apply the “dinosaur” label to his tracks because the finest minds of European paleontology had reconstructed dinosaur feet and body form in a totally erroneous fashion. Dinosaurs had at the time been built up from Jurassic megalosaurs and Cretaceous iguanodonts.


Crystal Palace Park Iguanodon 
Photo Credit: Wikiwand
http://avianmusing.blogspot.com/
Standard texts before 1870 made dinosaurs look like hybrid crocodiles/monitor lizards/bears/rhinos who padded around on flat-footed paws. Hitchcock knew that his Early Jurassic trackmakers were digitigrade and fundamentally avian, not plantigrade and fundamentally reptilian or mammalian. Hardly any osteologists detected strong avian influence.

Regardless of whether we think Edward Hitchcock was right or wrong, his 1858 Ichnology of New England monograph is one of the most important paleontological publications ever written, right up there with another one of my favorites, Odontornithes; a monograph by O.C. Marsh on the extinct toothed birds of North America, published in 1880. Remarkably, both publications are still relevant today.


An interesting spin-off tale from this posting was the surprising re-discovery of two local fossil sites documented in the 1858 monograph.

The first is the Portland Quarries (the early Mesozoic era—220 million to 195 million years ago), where Connecticut’s famous brownstone has been quarried for more than 300 years, and is frequently mentioned by Hitchcock in his fossil specimen accounts. 

But a little closer to home, in almost the exact location where I was photographing bird tracks last July, is a place called the Wethersfield Cove.

A popular birding destination of mine for well over twenty-five years, Hitchcock’s outstanding list of fossil track discoveries at the cove include Brontozoum giganteum, Grallator formosus, Agozoum dispari-digitatum, Platypterna deaniana, Platypterna tenuis and Platypterna delicatula.

Agozoum dispari-digitatum
Ichnology of New England 1858
Edward Hitchcock
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
Most interesting were his remarks about Ornithopus gallinaceus and Ornithopus gracilior, where he writes; Here again we have a remarkable resemblance in the track of this species to that of the common domestic hen, especially in the hind toe, which in that bird often shows only its extremity upon the mud and snow. But I have only a few good specimens, and, therefore, would be cautious in drawing conclusions from them.

Ornithopus tracks
Ichnology of New England 1858
Edward Hitchcock
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
He ends his remarks by saying; Would that I could have explored more thoroughly that remarkable locality of footmarks at the Cove in Wethersfield!

Wethersfield Cove track site, Connecticut USA
Ichnology of New England 1858
Edward Hitchcock
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/

This is only sentence in which Hitchcock uses an exclamation point (!) in his 1858 monograph. Of course, I was intrigued by that.  

So, I contacted a local expert and friend from the Great Meadows Conservation Trust, an organization that serves to protect and preserve the floodplain’s vital agricultural, scenic, archeological and wetland resources (4500 acres), to ask him a question regarding this little known fossil destination. 

My question to him; have you ever encountered red shale exposers anywhere around the Wethersfield Cove? Maybe canoeing? Do you know of any other sites along the river that have exposed red shale?

His prompt response; The red shale outcropping at the Cove is basically the embankment on the south side of the Cove that runs east-west with the Cove warehouse mounted on it.  Everywhere that's accessible by kayak is floodplain.

These red shale layers are the reason for the existence of the Cove. As the river flowed south from Hartford, it bounced off the ridge and made that huge "hook."  When the channel cut through the hook c. 1690, it left behind the Wethersfield and Keeny Coves.

The exposure at the Cove shows the ends of some of the layers, but not much of the surface of any particular layer, so, as far as I know, there are no visible tracks.

My last visit to the Wethersfield Cove was a quiet one, deep in thought and reflective. I easily found the red shale ends with the warehouse mounted on it. I knelt down before the shale, dusted off the freshly fallen snow, and gently touched the 200 million-year-old rock. I thought about the hidden tracks still buried beneath my feet, but mainly, I was thinking about Edward Hitchcock.
Wethersfield Cove sandstone end layers
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
I believe Hitchcock would have been very pleased to know that someone still cares about his life’s work, his incredible book, and above all, still looking for bird tracks at the Wethersfield Cove 160 years later.

Fossil track plates
Ichnology of New England 1858
Edward Hitchcock
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/

Saturday, December 9, 2017

The Avian Gizzard

The feeding of birds in winter is a favorite pastime of mine. It not only provides birds with the food they need to survive dangerously cold nights, it allows people like myself a convenient way to observe bird behavior at a relatively close range.

But I’m not the only one who appreciates these small winter gatherings. Sharp-shinned Hawks eagerly await the dawn arrival of finches, sparrows and doves to the feeding station, hoping to satisfy their own survival needs.

Accipiter Hawk
Photo Credit: Paul Cianfaglione
avianmusing.blogspot.com/
Even the glimpse of a distant accipiter can send feeder birds into turmoil, which sometimes ends with an individual striking a window or other object. When this happens, I tend to use the specimen as a learning tool, rather than burying it in a compost pile or throwing it back into the woods.

The Dark-eyed Junco (Junco hyemalis) I found resting near my homes foundation became the ideal specimen for dissection. It was a freshly dead bird, no decomposition whatsoever, which means it had to be opened up and examined immediately.

I removed feathers from the upper breast, lower breast and abdomen, pinned the wings to artist foamboard, then carefully sliced open the chest cavity. I cut away the large pectoral muscles from the sternum, lifted the sternum to reveal the innards.

Deceased Dark-eyed Junco
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/

Deceased Dark-eyed Junco
Photo Credit: Paul Cianfaglione
avianmusing.blogspot.com/
I separated a few of the organs to allow for pictures; these included the heart, liver, pancreas, duodenum and gizzard. Of all the organs, the gizzard, with its larger size and unique structure, drew most of my attention and then further study.  

Deceased Dark-eyed Junco
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
Pictured below is the juncos globular-shaped gizzard and part of the proventriculus.

Dark-eyed Junco Gizzard and Proventriculus
Photo Credit: Paul Cianfaglione
avianmusing.blogspot.com/
Birds have a much more complex and efficient stomach than their reptilian ancestors, but the avian stomach differs markedly in structure from the typical mammalian stomach. Birds have evolved a complex, two-part stomach that is a considerable improvement over the simple reptilian gizzard-like stomach. The first stomach area, the proventriculus, is a soft-walled glandular tube. The epithetlial cells of the gastric mucosa in the proventriculus secrete strong hydrochloric acids (pH 0.7 to 2.3), digestive peptic enzymes, and mucus and start the process of breaking down the structure of the food material. The food then passes to the second part of the stomach, the gizzard, a disk-shaped section posterior to the proventriculus with thick muscular walls and a hard, sandpaper-like inner surface. 

Avian Gizzard
Photo Credit: Paul Cianfaglione
Manual of Ornithology; Proctor
The gizzard performs the function of mammalian teeth, grinding and disassembling the food to allow the digestive enzymes a maximum of surface area to attack. In most birds the gizzard contains sand grains or small rocks to aid the grinding process. The gizzard is amazingly strong: it has been reported that the gizzard of turkeys can completely crush twenty-four walnuts (in the shell) in under four hours and turn surgical lancet blades into grit in less than sixteen hours (Streseman 1927-34). The gizzards of carnivorous birds can crush large bones, although most birds of prey regurgitate the bones, hair, scales and feathers of their prey in the form of pellets that are often found under or near their roosts (Source: Manual of Ornithology, Proctor N.S. 1993).

Avian digestive system
Image Credit: John Anderson; Ohio State University
http://avianmusing.blogspot.com/

After reading about the avian gizzard and taking a few close-up images, I decided to go a little further into my examination and cut directly into the organ. As it was just mentioned, the gizzard is amazingly strong, making it quite difficult to dissect, even with new scalpels

Once open, the gizzard revealed the juncos last meal of sunflower hearts, millet and husks. 

Dark-eyed Junco Gizzard
Photo Credit: Paul Cianfaglione
avianmusing.blogspot.com/
But not all birds need a powerful grinding gizzard, and birds that specialize in soft, easily digestible foods such as fruits and berries may have a gizzard that is substantially reduced in size and importance. Fruits and berries are rich in simple sugars, require little digestion, and pass rapidly through the avian alimentary canal. In fruit-eating euphonias, such as the Blue-hooded Euphonia, the gizzard may be reduced to a tiny nub of flesh on a stomach composed almost entirely of glandular proventriculus (Van Tyne and Berger 1959). 

Blue-hooded Euphonia Gizzard
Photo Credit: Paul Cianfaglione
From; Manual of Ornithology, Noble Proctor

Wednesday, December 6, 2017

A possible Lithornis vulturinus nodule from the London Clay Formation on the Isle of Sheppey, UK

It is extremely uncommon for a bird's fossilized bones to be preserved in its entire state, which makes it a challenge for any scientist to know exactly which species provided the skeleton. However, researchers can sometimes narrow down the identity of a potential candidate by comparing the bones of partial specimens to other well-known fossils, and of course extant birds.  

But when ancient birds are found fully articulated, or remarkably preserved in a three-dimensional form, interest in these fossils jump exponentially.

This was the case with Lithornis vulturinus (MGUH 26770), from the Lower Eocene of Denmark, which was initially described in 2005, and then more thoroughly examined in 2015.
Lithornis vulturinus MGUH 26770
Photo Property of Estelle Bourdon
http://avianmusing.blogspot.com/
Lithornis is a genus of extinct paleognathous birds; Paleocene-Eocene, 56–40 Ma. Lithornis were able to fly well, but are closely related to today's tinamous (which are poor flyers) and ratites (which are flightless birds) (Source: Wikipedia).

Knowledge of this astonishing fossil (MGUH 26770) was first brought to my attention two years ago, shortly after acquiring my own purported Lithornis fossil bird. No, this wasn’t a new and exceptionally well-preserved specimen, but a clay nodule of sorts, a rolled-up mass of bird bones.

Possible Lithornis vulturinus fossil
Photo Credit: Paul Cianfaglione
http://avianmusing.blogspot.com/
Recovered from the London Clay Formation on the Isle of Sheppey, UK (Lower Eocene Epoch), this fossil nevertheless offered a number of details including a few complete bones. The London Clay, well known for its fossil content, is a stiff bluish clay which becomes brown when weathered.


Possible Lithornis vulturinus fossil
Photo Credit: Paul Cianfaglione
https://avianmusing.blogspot.com/

"Lithornis" is from ancient Greek for "stone bird", as it is one of the first fossil birds to become widely discussed. L. vulturinus was described as a vulture by Owen (1840) from the holotype fossil 955 738 - TM 024 717. The fossil was collected from Early Eocene London Clay deposits on the Isle of Sheppey, Kent, England by J. Hunter before 1793. This fossil was destroyed by bombing in World War II. Numerous isolated fossil bones of Lithornis vulturinus were incorrectly described anew, such as Parvigyps praecox and Promusophaga magnifica - the supposed earliest vulture and turaco, while others were referred to existing families of neognathous birds. A neotype (BMNH A 5204) was erected to replace the holotype in 1988 by Houde, who for the first time diagnosed it as a paleognath based on complete three-dimensional skulls and skeletons of congeners from North America. (Source: Wikipedia).

Lithornis vulturinus paleoart
Image credit: Wikipedia
http://avianmusing.blogspot.com/
In this post, I would like to present photos of my alleged Lithornis nodule, and go over some of the pertinent information presented in the 2015 paper, A redescription of Lithornis vulturinus (Aves, Palaeognathae) from the Early Eocene Fur Formation of Denmark (Bourdon, Lindow). It is with this detailed re-description that I hope to learn more about this recent acquisition.  

Let’s start with the abstract of the 2015 paper and part of the introduction, before moving into the gleaning process and comparative bone study. Please refer to Baumel and Witmer for further inquiries;


Abstract;

The extinct Lithornithidae include several genera and species of flying palaeognathous birds of controversial affinities known from the Early Paleogene of North America and Europe. An almost complete, articulated skeleton from the Early Eocene marine deposits of the Fur Formation (Denmark) was recently assigned to Lithornis vulturinus Owen, 1840. This study provides a detailed redescription and comparison of this three-dimensionally preserved specimen (MGUH 26770), which is one of the best-preserved representatives of the Lithornithidae yet known. We suggest that some new features might be diagnostic of Lithornis vulturinus, including a pterygoid fossa shallower than in other species of Lithornis and the presence of a small caudal process on the os palatinum. We propose that Lithornis nasi (Harrison, 1984) is a junior synonym of Lithornis vulturinus and we interpret minor differences in size and shape among the specimens as intraspecific variation. To date, Lithornis vulturinus is known with certainty from the latest Paleocene—earliest Eocene to Early Eocene of the North Sea Basin (Ølst, Fur and London Clay Formations). Among the four species of the genus Lithornis, the possibility that Lithornis plebius Houde, 1988 (Early Eocene of Wyoming) is conspecific with either Lithornis vulturinus or Lithornis promiscuus Houde, 1988 (Early Eocene of Wyoming) is discussed. The presence of closely related species of Lithornis on either side of the North Atlantic in the Early Eocene reflects the existence of a high-latitude land connection between Europe and North America at that time.

Introduction;

The extinct Lithornithidae are chicken-sized flying palaeognathous birds that were an important and diverse component of the Northern hemisphere avifaunas in the Paleocene and Eocene (60 to 48 million years ago). The only other flying palaeognaths are the Tinamidae (tinamous), which appear in the fossil record in the Early Miocene (Bertelli et al. 2014) and are represented today by 47 species inhabiting Central and South America (del Hoyo et al. 1992). The lithornithids had slender beaks equipped with foveae for sensory corpuscles that they probably used to probe along bodies of water (Houde 1988). Morphology of the wing bones, shoulder girdle and sternum suggest that lithornithids may have been better flyers than the Tinamidae (Houde 1988). The long hallux and curved claws of the lithornithids also suggest perching abilities (Houde 1988). Although Richard Owen described the first lithornithid species, Lithornis vulturinus Owen, 1840, in the nineteenth century (Owen 1840, 1841, 1846), Lithornithidae were not recognized as palaeognaths until the 1980s (Houde & Olson 1981; Houde 1986, 1988). Isolated bones of these enigmatic birds are superficially more similar to a number of neognaths than they are to any modern palaeognath group. Thus, their true identity has confounded taxonomists for over a century (Houde 1988).

As I mentioned earlier, the nodule held a number of bones, some of which I have tentatively identified as a partial humerus, pelvis, furcula, radius, highly degraded femur (?) and possible skull fragments. The more complete bones include one scapula, synsacrum and a cervical.

The paper describes the corpus scapulae as slender, poorly curved and narrow. In MGUH 26770, the acromion is remarkably elongated, with a pointed tip that projects cranially. The acromion is not preserved in the neotype of L. vulturinus. In MGUH 26770, the acromion shows a pneumatic foramen on its lateral face and a small tubercle on its dorsal face. The facies articularis humeralis is narrow and separated from the acromion by a deep notch. The prominent acromion is a salient characteristic of the Lithornithidae (Houde 1988).

Possible Lithornis vulturinus fossil
Photo Credit: Paul Cianfaglione
https://avianmusing.blogspot.com/
After reading this passage, I quickly realized that the scapula was not a complete bone, but missing most of the acromion as well as the facies articularis humeralis. However, the slender, poorly curved and narrow nature of the bone was still evident. The description also states that the length of the MGUH 26770 scapula as 67.0 mm, as opposed to my fossil, which at best measures 35.0 mm. Should I chalk this size discrepancy up as an example of intraspecific variation?

Oddly, the structural description of the scapula seems to contrast with the initial account of L. vulturinus below (MGUH 26770) in 2005;  


The glenoid facet of the proximal scapula is turned medially where it articulates with the coracoid (itself relatively narrow in MGUH 26770 and separated from the acromion by a deep notch). The blade of this element is markedly curved along its entire length and tapers to a point proximally, similar to some of the larger specimens described by Houde (1988); curvature of the scapula is not seen in smaller Lithornithidae, which have long, straight, and narrow blades.

The synsacrum is remarkably preserved in the clay nodule, and similarly described (below) in the 2015 paper. Photos in both the 2005 and 2015 research papers seem to support structural similarities with MGUH 26770.

The synsacrum is broken in its caudal end. It is not fused to the ilium (i.e. there is no sutura iliosynsacralis). The first vertebra synsacralis shows foveae costales. The synsacrum is narrow in its cranial part, and shows a prominent crista spinosa synsacri. Caudal to the three cranial most vertebrae synsacrales, the synsacrum widens considerably and the crista spinosa synsacri lowers and widens. Two rows of small foramina intertransversaria are preserved on either side of the synsacrum. No vertebrae caudales are preserved.

Possible Lithornis vulturinus fossil
Photo Credit: Paul Cianfaglione
https://avianmusing.blogspot.com/
Below is a description of the unusual two rows of small foramina intertransversaria in Baumel & Witmer. See my blogs listing of favorite sites for convenient access to Baumel & Witmer.   

Lamina transversa notarii/synsacri. During skeletal maturation the transverse processes of the notarial and synsacral vertebrae become coalesced, producing on each side a continuous transverse lamina. In mature birds the lateral border of each Lamina of the synsacrum becomes firmly ankylosed with the hip bone (as coxae) of its side. In instances where the fusion between the transverse processes is incomplete, the persistent windows are known as Fenestrae intertransversariae. The fenestrae as well as smaller foramina are traversed by nerves and vessels.

Do the windows (fenestrae) observed in my synsacrum indicate an immature bird?

Features of the pictured cervical; see Baumel & Witmer again for a detailed diagram.

Possible Lithornis vulturinus fossil
Photo Credit: Paul Cianfaglione
https://avianmusing.blogspot.com/
The zygapophyses of the vertebrae cervicales are slender and their facies articulares are longer than wide. Lacuna interzygapophysialis; Lacuna is the V-shaped or often broadly V-shaped indentation of the Lamina dorsalis of the vertebral arch, located between the right and left zygapophyses (Fig. 4.8C) at each end of a vertebra. Vertebrae from the cranial and intermediate series bear processus costales, which are elongated and spine-like in C4 to C11. The corpus vertebrae are bilaterally constricted in C4 to C12. The narrow corpus occurs in other lithornithid species (Houde 1988).

There also appears to be two sections of the cranium in the nodule. These sections include, in my opinion, the frontal and the parietal, with a clear sutura frontoparietalis visible.

Cranium. The cranium of MGUH 26770 is partially hidden by matrix, and is visible in occipital (Fig. 2), ventral (Fig. 3) and right lateral views (Fig. 4). Only the caudolateral part of the os frontale is visible. The sutura frontoparietalis and sutura laterosphenofrontalis remain completely open despite the specimen belongs to an adult individual, as in the neotype of Lithornis vulturinus (NHMUK A5204). The sutura frontoparietalis and sutura laterosphenofrontalis also remain open in adulthood in other lithornithids (Houde 1988) and tinamous (Elzanowski & Galton, 1991). (Source; A redescription of Lithornis vulturinus (Aves, Palaeognathae) from the Early Eocene Fur Formation of Denmark (Bourdon, Lindow).

Possible Lithornis vulturinus fossil
Photo Credit: Paul Cianfaglione
https://avianmusing.blogspot.com/
I also found a research paper called Cranial osteology in Tinamidae (Birds: Tinamiformes), with systematic considerations (Luís Fábio SilveiraI; Elizabeth Höfling II) in Portuguese. Though I was not able to translate the paper to English, the images provided were a tremendous help with comparative examples.




The remainder of bones in the nodule were unfortunately too incomplete, and lacking key features, for further scrutiny.

Prior to the acquisition, it was mentioned that the fossil bird may be a member of the extinct Lithornithidea.

How they (paleontologist/collector) came to that conclusion, I believe, would be through the identification of the skull fragments and synsacrum. If that’s the case, I concur.

Lastly, I would like to go back and offer a brief parting thought about the woodcut of the L. vulturinus holotype.  
Woodcut of the Lithornis vulturinus holotype
Image Credit: Wikipedia
https://avianmusing.blogspot.com/
L. vulturinus was described as a vulture by Owen (1840) from the holotype fossil 955 738 - TM 024 717. The fossil was collected from Early Eocene London Clay deposits on the Isle of Sheppey, Kent, England by J. Hunter before 1793. This fossil was destroyed by bombing in World War II (Source; Wikipedia).

If I had to pick one unique or special feature about this particular fossil, it would have to be its likeness to the L. vulturinus holotype. One has to wonder, is this clay nodule similar to the one Professor Owen once held in his hands before erecting this new species to science? For me, it’s kind of a romantic thought.