Re: Feathered Dragons: Studies on the Transition from Dinosaurs to Birds

["Mickey Mortimer" <Mickey_Mortimer111@msn.com>]

Tim Williams wrote-

>> the absence of diplodocids there is no more proof of endemism of Late
Jurassic Chinese taxa than the
>> presence of dicraeosaurids and absence of camarasaurids in the Tendaguru
is of endemism of Late
>> Jurassic Tanzanian taxa.
>
> Excuse my nit-picking, but I remember reading that the Tendaguru sauropod
_Janenschia_ might actually
> be a camarasaurid.

I've heard that suggested to, but what's the evidence?  And I could just
restate it as "absence of haplocanthosaurs in the Tendaguru".

>> Bakker and Bir, 2004. Dinosaur crime scene investigations: Theropod
behavior at Como Bluff, Wyoming, >> and the evolution of birdness. 301-342.
>
> Sounds like it could be an interesting article.  Is it?

I hadn't read everything before my first post, hence the lack of comments on
some papers.  Now I've gone through almost the entire book, so can provide
more.  As for Bakker's article, I was pleasantly surprised.  I'm not a fan
of Bakker's style in general, but the article's thesis seems sound- shed
dinosaur teeth are abundant and dropped while the organism was alive, so can
be used to show preferred habitats of various taxa.  A good level of
statistical data, though some of the higher level inferences seem less
certain.  Having all sizes of Allosaurus teeth preserved at a feeding site
could just as easily mean juveniles moved in to scavenge sauropods killed by
adults than it could indicate adults fed juveniles, as advocated by Bakker.

> Thanks for the summary, Mickey.  Is the book worth buying, in your
opinion?

It definitely was for me.  I see this book as "Feathered Dragons:
Dromaeosaurs and Some Other Stuff".  A good half the book gives new
information on dromaeosaurs, which is worth my money.  I also found the
brooding/egg chapters quite worthwhile.

Further comments I can make now-

Bakker, 2004. Introduction: Dinosaurs acting like birds, and vice versa - an
homage to the Reverend Edward Hitchcock, first director of the Massachusetts
Geological Survey. 1-11.
Interesting essay on why Hitchcock was fairly accurate for his time.

Russell, 2004. The dinosaurian setting of primitive Asian birds. 15-34.
Interestingly notes the smallest Djadochta theropods are probably known
since little lixards and mammals are so common.  But with only one Apsaravis
specimen, and several new small theropod taxa on the way, I don't think
sampling is good enough to say this yet.  The "Distribution of Late
Cretaceous Families of Dinosaurs" table goes a long way to show why
biostratigraphy is near worthless for dinosaurs.  It shows the differing
distributions of 21 taxa in three areas- Mongolia, Dinosaur Park, and Hell
Creek.  Of the ten taxa not found everywhere, three are monogeneric
(Bagaraatan, Deinocheiridae, Avimimidae).  Avimimids and therizinosaurids
are now known from the Dinosaur Park Formation, and lambeosaurines are now
known from the Hell Creek.  Having "hypsilophodontids" (for Parksosaurus)
and thescelosaurids (for Thescelosaurus and Bugenasaura) is misleading when
the latter two haven't been found to clade together in phylogenetic
analyses.  And since when are Dinosaur Park titanosaurs or homalocephalids
known?  Then there are the carnivore/herbivore species ratios compared to
mammals.  Supposedly there were more dinosaurian carnivore species per
herbivore species, but this doesn't hold up when you look at how it's being
calculated.  In the Djadochta, ornithomimids, oviraptorids, Avimimus and
troodontids are all counted as carnivorous, despite being possibly
omnivorous/herbivorous.  Hadrosaurs and titanosaurs were ignored because
they were supposedly allochthonous.  Similar problems exist for the other
formations.

Burnham, 2004. New information on Bambiraptor feinbergi (Theropoda:
Dromaeosauridae) from the Late Cretaceous of Montana. 67-111.
All done coding this taxon (came out sister to a sinornithosaur-microraptor
clade basal to other dromaeosaurs), and I'm glad to see the details I made
out using small photos of the disarticulated remains I found online were not
misleading in regards to my coding it (I think only three characters were
miscoded).  I was able to add over 100 coded states though, and a few for
Deinonychus too.  I'm disappointed by the complete lack of vertebral
illustrations, and paucity of axial data.  Still, it's better than we have
for any other dromaeosaur besides Deinonychus.

Currie and Varricchio, 2004. A new dromaeosaurid from the Horseshoe Canyon
Formation (Upper Cretaceous) of Alberta, Canada. 112-132.
Done coding this taxon too (came out sister to Dromaeosaurus and
"Alashansaurus" deep within Dromaeosauridae), and the data matrix
facilitated coding Bambiraptor, Saurornitholestes and Deinonychus.
Apparently Currie and Varricchio believed Megaraptor was non-dromaeosaurian
from the start- "Megaraptor was also compared to dromaeosaurids because of
its sickle-like claw, although it was always clear that it is not related."
Atrociraptor teeth can be distinguished from Saurornitholestes teeth by
their enamel extending more basally on the mesial edge.  Oh, and what
happens to dromaeosaurid interrelationships when the outgroup to their
matrix is Archaeopteryx and Sinovenator instead?  Um... nothing.  And if
Sinornithosaurus is added, it becomes a velociraptorine excluded from the
Bambiraptor-Deinonychus-Atrociraptor clade.

Norell, Makovicky and Clark, 2004. The braincase of Velociraptor. 133-143.
A more detailed description than done by Barsbold and Osmolska (1999), and
with good photos too.  Already we have conflict of character descriptions,
with Currie and Varricchio coding Bambiraptor as having a twisted
paroccipital process, but Norell et al. claiming it didn't have one.  Also
notable is the continuation of Currie (yes) vs. Norell (no) in whether
troodontids have pneumatic basal paroccipital processes or not.

Godfrey and Currie, 2004. A theropod (Dromaeosauridae, Dinosauria) sternal
plate from the Dinosaur Park Formation (Campanian, Upper Cretaceous) of
Alberta, Canada. 144-149.
It's a dromaeosaur sternum.  Maybe Saurornitholestes, maybe Dromaeosaurus.
Very similar to Velociraptor's.  Has coracoid facets, like Velociraptor and
Bambiraptor (remember when ABSRDists used this as an ornithurine
character?).

Novas, 2004. Avian traits in the ilium of Unenlagia comahuensis
(Maniraptora: Avialae). 150-166.
Settles the debate of Unenlagia's cuppedicus fossa (present, and laterally
overhung), which is similar to Deinonychus'.  Unenlagia oddly has a
supracetabular crest, though it's restricted anteriorly and has a sharply
pointed component.

Wright, 2004. Bird-like features of dinosaur footprints. 167-181.
A nice start at realizing theropod pedal morphologies vary enough to be used
to assign ichnites to various clades.  In particular, recognizes
tyrannosauroid and ornithomimosaur prints will have more subequal side
digits than other theropods.

Grellet-Tinner and Chiappe, 2004. Dinosaur eggs and nesting: Implications
for understanding the origin of birds. 185-214.
Misread the figure when I reported the first time.  It takes a tree length
of 22 steps (not 22 more steps) to place Aves sister to Crocodilia.  That
hypothesis is 11 steps longer than BAD.  A nice description of several kinds
of eggs.

Varricchio and Jackson, 2004. Two eggs sunny-side up: Reproductive
physiology in the dinosaur Troodon formosus. 215-233.
Great summary of Troodon egg and brooding data.  Seems Troodon may have had
a third layer on its eggs, which was an avian character in Grellit-Turner
and Chiappe.  This would be another character to place it closer to birds
than Citipati.

Hopp and Orsen, 2004. Dinosaur brooding behavior and the origin of flight
feathers. 234-250.
A nice rationale behind elongating remiges, asymmetrical remiges and the
folding wing.  I think WAIR explains elongating remiges and the flight
stroke better though.  And why do neoflightless brooding taxa have
symmetrical remiges if asymmetrical ones are still so useful for brooding?
Also doesn't explain the retrices, which seem to evolve around the same time
as remiges.

Chatterjee and Templin, 2004. Feathered coelurosaurs from China: New light
on the arboreal origin of avian flight.
Some really sad little drawings of coelurosaurs.  I think their cladograms
showing reduction of forelimbs in terrestrial theropods (Ceratosaurus >
Allosaurus > Tyrannosaurus), and elongation in arboreal theropods
(Sinosauropteryx > Caudipteryx > Protarchaeopteryx > Sinornithosaurus >
Archaeopteryx) are misleading.  Caudipteryx has very short arms for an
oviraptorosaur, Protarchaeopteryx's position is uncertain, etc..  I'm amazed
at their ability to calculate Protarchaeopteryx's parachuting trajectory,
given we don't know the wing or tail shape or area.  Same with
Sinornithosaurus (based only on the holotype), though it has a gliding
trajectory.  There's a discussion of feather ontogeny and phylogeny without
a single mention of Prum and Brush's work.  They still have that Early
Jurassic vegetation print as the earliest record of feathers.

Mickey Mortimer