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Details on Protoavis :-) Part 1



:-D On Super RTL (a German commercial TV) there just ran The Land That Time
Forgot (GB 1975). ROTFL!!! "The farther we go upstream/north, the further
the organisms perfect themselves"... "Each of the groups will be, one after
another, sent for building, hunting and oil refining." Dinosaurs made of
papier maché. LOL... :-D Long live Jurassic Park!!!

Back to the really important things. "Revelations forthcoming", I wrote a
few days ago. Well, though the article

Sankar Chatterjee: *Protoavis* and the early evolution of birds,
Palaeontographica Abt. A 254, Lfg. 1 -- 3, 1 -- 100 (Oktober 1999)

is more detailed than the book

Sankar Chatterjee: The Rise of Birds. Johns Hopkins 1997,

it is paradoxically less up-to-date, because the article was received by
Palaeontographica in 1994, accepted for publication in 1995, and apparently
just lay around there for the next 4 years (and nobody corrected the
typos... :.-( All mistakes in the English of the quotes, such as omissions
of articles, are his!). This means that important new fossils lack from the
analyses.

However:
*Protoavis* comes from two stratigraphic levels, with about 60 m, the whole
Trujillo Formation and the Carnian-Norian boundary in between (wasn't there
a mass extinction?). The upper site in the Norian Cooper Canyon Formation
has yielded "[t]wo *Protoavis* skeletons that were found jumbled together".
"No other tetrapod species has been found close or mixed with the
*Protoavis* skeletons [holotype and paratype]. The orientation of the
*Protoavis* bones as they were found in the mudstone was given elsewhere
(CHATTERJEE 1991, Fig. 2)." So this is the place where to look for
chimaerae. "The Kirkpatrick Quarry ([Carnian] Tecovas Formation), on the
other hand, has yielded largely aquatic and semiaquatic vertebrates [...]
The mixing of different kinds of vertebrate bones and their disarticulated
nature [no, he is NOT speaking of the two "individuals" that contain most of
the bones, these are from above] may represent attritional samples in a pond
deposit. The presence of carbonate granular conglomerate, organic matter,
coprolites, and abundant fish fauna also support the depositional history of
the Kirkpatrick quarry in a pond environment. Several isolated postcranial
elements of *Protoavis* have been collected from a small mound of 1 m². As
new bones are exposed after a heavy shower from this conglomeratic layer,
this site has been monitored over a period of several years and a large
amount of surface collection has been made. The preservation is excellent in
the Kirkpatrick quarry and needs very little preparation."

To give an estimate of how disarticulated the material is and is not:

        "H o l o t y p e :  TTU P 9200, partial skull and postcranial
material of a subadult individual from the [P]ost quarry, Cooper Canyon
Formation (Pl[ate]. 1); estimated total length 60 cm, about the size of the
Solnhofen specimen of *Archaeopteryx*.
        R e f e r r e d   s p e c i m e n s :  TTU P 9201, partial skull and
postcranial material of a juvenile individual from the Post quarry, Cooper
Canyon Formation (Pl. 2), about half the size of the holotype, and
corresponds to the Eichstätt specimen of *Archaeopteryx*, TTU P 9350 --
9380, isolated skeletal material including a right partial jaw (9364),
vertebrae (9350 -- 9359), left coracoid (9360), sternum (9361), humeri
(9362, 9[3]63, 9[3]65) [typos in the original in this place!!!], radii
(9367, 9368)[,] ulna (9369), femora (9370 -- 9373), tibia (9374) and
phalanges (9375 -- 9380) from the Kirkpatrick quarry, Tecovas Formation. All
material of *Protoavis* is housed at the Paleontology Division of the Museum
of Texas Tech University, and the institutional abbreviation is TTU P."

        "D i a g n o s i s :  An ornithothoracine bird (sensu CHIAPPE &
CALVO 1994) [ = *Sinornis* + Neornithes, but see my remarks on the cladogram
respectively his 1997 book] having reduced dentition, frontally placed
enormous orbits, a relatively large lateral (tympanic) Eustachian foramen
without parasphenoid cover; axis with anterior hypapophysis; a pneumatic
scapula with a short acromial process, proximal and distal expansions of the
coracoid at an oblique plane, a coracoideal sulcus for the sternal
articulation, sternum bearing a V-shaped articular surface for the coracoid,
possible quill knobs on the metacarpals II and III, anteroventral process of
the ilium highly pronounced and twisted, a strongly developed renal fossa
bounded by the ilioischiadic pila, a large nutrient foramen on the distal
femur, and an overhanging tibial crest on the fibular shaft.
        C o m m e n t s :  The postcranial skeletons of *Protoavis*
collected from the Post and Kirkpatrick quarries show slight morphological
differences, but these morphs are attributed to ontogeny, individual
variation, and possible sexual dimorphism rather than taxonomic difference.
A large array of morphological variations within a single species is known
among archosaurs, such as [partly chimaeric] *Postosuchus* (CHATTERJEE
1985), *Coelophysis* (COLBERT 1990), and *Syntarsus* RAATH 1990). It is
likely that all the *Protoavis* material from the Dockum Group [all _is_
from the Dockum Group] represents the monotypic species, *P. texensis*; the
minor postcranial differences are probably related to sex, age, or
diagenetic distortion. Three different growth stages on the basis of size
are encountered in the postcranial material: small/juvenile (9201), subadult
(9200), and fully adult/mature (9362, 9363). Among these specimens, nearly
every skeletal element of *Protoavis* is represented."

Just to cast a bit of doubt over his identifications... and to give an
impression of why the paper has 100 pages, not counting the plates:

"Modifications to the previous interpretation of the skull of *Protoavis*

        Although the skull of *Protoavis* has been adequately described
(CHATTERJEE 1991), further preparation, recovery of additional material, and
subsequent comparison with extant taxa have prompted me to amend several
features from my original interpretations and restorations.
        (1) A right maxilla, concealed between two iliac blades, has been
separated. It does show the ascending process (Pl. 3c) as had been
speculated in my earlier paper.
        (2) The lacrimal bone figured earlier was reversed; the bone is now
fully prepared and shows the typical dorsal bar pointing caudally as in
modern birds (Pl. 3b). [Is this the "L-shaped lacrimal" of dromaeosaurs?]
        (3) Further preparation of the quadrate has revealed an additional
pneumatic foramen near its head (Fig. 2b, 2c; Pl. 3g, 3h).
        (4) A large palatal process of the premaxilla was shown previously
(CHATTERJEE 1991, Fig. 11a), but it now appears that the premaxilla has
little palatal component behind the symphysis and might have contacted the
vomer posteriorly (Fig. 3b).
        (5) The structure figured as a 'sternal plate' (CHATTERJEE 1991,
Fig. 3p, 3q) probably represents part of the vomer and pterygoid bar
bordering the choana [!!!]; the anterior part of the vomer is also preserved
in this specimen (9200). A beautiful [strange-looking] keeled sternum from
the Kirkpatrick quarry has resolved the true identity of this palatal
element.
        (6) In the previous skull restoration (CHATTERJEE 1991, Fig. 9b),
the braincase has been placed far forward in relation to the quadrate and
the skull roof so that the otic capsule occurs in front of the quadrate; in
reality, the otic structures (outer and middle ear regions) would be located
in a space between the quadrate head and the paroccipital process. In the
new restoration, the braincase has been placed accordingly to maintain its
topographic relationship with the quadrate (Fig. 2a).
        (7) The interpretation of the braincase, especially the
basisphenoid-parasphenoid complex, was found extremely difficult due to lack
of comparative material (Pl. 3f). Recently I was able to study the
three-dimensional model of the skull of *Rhea* and the serial sections
prepared and described by MÜLLER (1961, 1963) [...]. I have also dissected
the middle ear region of chicken (*Gallus*) for comparison. This study has
clarified several details of the braincase of *Protoavis*. Previously I had
identified two pneumatic foramina at the posterior and ventral surface of
the parabasisphenoid [there are lots of bones in the braincase, but what's
this?] (CHATTERJEE 1991, Fig. 12j). In modern birds, on the other hands, no
pneumaticity is known in these regions. Instead, the carotid foramen at the
entrance of the parabasal canal [whatever that is] occurs in the same
position as the putative ventral pneumatic position; the posterior foramen
probably represents the entrance of the palatine branch of facial nerve to
the parabasal canal. Once these two foramina are identified properly, the
remaining foramina in the anterior part of the braincase have clear
homologues in extant avian species. The large foramen adjacent to the
anterior tympanic recess that was previously labeled as the carotid foramen
(CHATTERJEE 1991, Fig. 13a) now becomes the lateral Eustachian ( = auditory)
foramen of the tympanic end (Figs. 4a, 5a)."

And so on through number (14).

The interesting things will come tomorrow and later because it's past
midnight over here and I'm tired.

I can send scans of the pages that contain the following figures within a
few days to anyone who asks:

Figures are drawings, plates are photos. I'll send the abbreviations
(inhumanely placed in the appendix) with all drawings except Fig. 1.

"Fig. 1. C: composite geologic section of the Dockum Group showing the two
stratigraphic levels of *Protoavis*."
Fig. 2, 3, 4 and 5: composite restoration of skull, 2 showing the skull in
lateral view and the quadrate, 3 showing the skull in dorsal, ventral and
occipital views, 4 and 5 showing the braincase.
"Table 1. Estimated skull and jaw dimensions (in mm) of Protoavis texensis
(based on TTU P 9200)."
"Table 2. Vertebral counts in various theropod species". Includes lots of
birds.
"Table 3. Measurements (in mm) of vertebrae of *Protoavis texensis*."
Fig. 6: Anterior cervical vertebrae of *Protoavis texensis* and *Aquila
chrysaetos*.
Fig. 7: Posterior cervical vertebrae of *P.*.
Fig. 8: Dorsal vertebrae of *P.*.
Fig. 9: Sacral and caudal vertebrae of *P.*.
"Fig. 10. Neural canal indices of various theropod genera. Note *Protoavis*
and modern birds have much higher NCI values (>60) than the condition in
nonavian theropods."
"Table 4. Measurements (in mm) of the elements of shoulder girdles of
*Protoavis texensis*."
Fig. 11: Scapula, coracoid, furcula and sternum of *P.*, with a comparison
to the furcula of a chicken.
Fig. 12: Composite restoration of the shoulder girdle plus comparison of
sternum to that of a chicken.
Fig. 13: Shoulder girdles of *Archaeopteryx*, *Iberomesornis* and
"Enantiornithes".
Fig. 14: Humeri.
Table 5: Measurements of arm bones.
Fig. 15: Forearm elements.
Table 6 (incorrectly labeled as 2): Measurements of elements of the right
hand.
Fig. 16: The odd hand of *P.*.
Fig. 17: Pelvis.
"Table 7. Preacetabular elongation (PE) indices of some nonavian theropods
and birds."
Fig. 18: Composite restorations of pelvic girdles of *P.*, "Enantiornithes",
a turkey and *Archaeopteryx* (still wrong with pubis pointing, say, 30°
backward).
Table 8: Measurements of pelvic elements. + Table 9: Measurements of leg
elements.
Fig. 19: Femora.
Fig. 20: Tibia, fibula and astragalocalcaneum (low ascending process, as in
figured *Alwalkeria*).
Table 1[0]: Measurements of elements of the (only known) foot.
Fig. 21: A composite restoration of a foot that cries "perching bird", plus
claw measurement studies.
Fig. 22: Composite skeletal restoration.
Fig. 23: Life restoration.
"Fig. 24. Lines of actions of some principal muscles of the pelvis and femur
of *Protoavis*; right lateral view."
"Table 11. Femora[sic]/tibiotarsal (FT) indices in some theropods."
"Fig. 25. Stick diagram showing the running posture of *Protoavis* [...]
Note movements of the knee, rather than femoral retraction, accounts for
most of the foot displacement."
Fig. 26: The wing in flexion and extension.
Fig. 27: Restorations of flight muscles in frontal view.
"Fig. 28. Scansorial adaptation of a hypothetical proavian maniraptoran
(similar to *Velociraptor*)"; the book says "protodromaeosaur", and in the
illustration there the skeleton lacks the large opposed hallux it has in the
article.
"Fig. 29. Evolution of avian coracoid showing the progressive transformation
of origin for M. biceps brachii and M. supracoracoideus."
"Fig. 30. Hypothetical stages for evolution of major forms of avian flight
in arboreal mode." This figure and its caption are much more detailed in the
book.
Fig. 31: Tip vortices in a proavian protodromaeosaur and *P.*. This
illustration has a modern bird for comparison in the book.
Fig. 32: Uninteresting simple cladogram of Dinosauria.
Fig. 33: Various historical cladograms of birds and their relatives:
Thulborn 1984, Gauthier 1986, Cracraft 1986, Sanz & Bonaparte 1992, Martin
1987, Chiappe & Calvo 1994, Sereno & Rao 1992, Perle et al. 1993.
Fig. 34: Skulls and temporal regions of *Archaeopteryx* (wrong -- has been
shown to have an ascending process on the jugal, ~ corrected in the book),
*Avimimus*, *Protoavis*, *Hesperornis* and *Ichthyornis*.
Fig. 35: Holotype of *Ambiortus dementjevi* as found, plus interpretations.
Fig. 36: A few bones of *Patagopteryx*.
Fig. 37: Most parsimonious cladogram that results from
Table 12, a data matrix for 84 characters and 14 taxa.
Fig. 38: The cladogram of Fig. 37 plotted with a time scale.

All plates, especially the stereophotographs, in meager quality in the
original and in plain bad quality in my photocopies.
Plate 1: holotype.
Plate 2: paratype.
Plate 3: 3D photos of cranial elements of the holotype.
Plate 4: same for paratype.
Plate 5: 3D photos of vertebrae.
Plate 6: same of shoulder girdle elements.
Plate 7: same of humeri.
Plate 8: same of forearm and hand elements.
Plate 9: same of pelvic and leg elements.
Plate 10: comparisons of ascending processes. Includes foot of *P.*.