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Hongshanornis, "Archaeorhynchus" and ornithuromorph phylogeny
With the recent publication of Hongshanornis by Zhou and Zhang (2005), we
are provided with more information about basal ornithuromorphs. They coded
it and an unpublished taxon, "Archaeorhynchus", in the matrix of Clarke
(2004) (NOT Norell and Clarke, 2001 as they claim). In addition, they added
Yanornis, Yixianornis, Jeholornis (from Zhou and Zhang, 2002 presumably),
Sapeornis (partially from Zhou and Zhang, 2002, but with new info from Zhou
and Zhang, 2003), Liaoningornis and claim to have added Confuciusornis,
though Norell and Clarke already included it. They provide the following
cladogram-
|--Dromaeosauridae
`--+--Archaeopteryx
`--+--Shenzhouraptor
`--+--Sapeornis
`--+--Confuciusornis
`--+--Vorona
`--+--+--Sinornis
| `--+--Neuquenornis
| `--+--Gobipteryx
| `--Concornis
`--+--Hongshanornis
`--+--+--Liaoningornis
| `--+--Yanornis
| `--Yixianornis
`--+--Apsaravis
`--+--+--Baptornis
| `--Hesperornis
`--+--Ichthyornis
`--+--Lithornis
|--Crypturellus
`--+--+--Chauna
| `--Anas
`--+--Gallus
`--Crax
However, after running their matrix (with or without characters 89 and 97
excluded, as they are supposed to be), I fail to retrieve their tree.
Instead- enantiornithines are a polytomy; Confuciusornis, Vorona and
Enantiornithes are in a poytomy with Euornithes; and the Euornithes base is
a polytomy between Liaoningornis, Hongshanornis, Yanornithidae and
Apsaravis+more derived birds. When I run Zhou and Zhang's complete matrix,
including Patagopteryx and "Archaeorhynchus", the result is-
|--Dromaeosauridae
`--+--Archaeopteryx
`--+--Shenzhouraptor
`--+--Sapeornis
`--+--+--Confuciusornis
| `--+--Vorona
| |--Sinornis
| |--Concornis
| |--Neuquenornis
| `--Gobipteryx
`--+--Patagopteryx
`--+--Liaoningornis
|--Hongshanornis
|--"Archaeorhynchus"
`--+--Yanornis
`--+--Yixianornis
`--+--Apsaravis
`--+--+--Baptornis
| `--Hesperornis
`--+--Ichthyornis
`--+--+--Lithornis
| `--Crypturellus
`--+--+--Chauna
| `--Anas
`--+--Gallus
`--Crax
As the matrix was taken from Clarke (2004), which was in turn from Clarke
(2002), I decided to add the taxa Clarke (2002) did to test their positions.
Upon doing so, I realized the Liaoningornis coded by Clarke (2002) and the
one coded by Zhou and Zhang differed immensely. The resulting strict
consensus cladogram is shown below-
|--Dromaeosauridae
`--+--Archaeopteryx
`--+--Shenzhouraptor
`--+--Sapeornis
`--+--+--Confuciusornis
| |*-Chaoyangia
| `--+--Sinornis
| |--Concornis
| |--Neuquenornis
| |--Gobipteryx
| `--+--Vorona
| `--Liaonigornis sensu Clarke
`--+--Patagopteryx
`--+--Hongshanornis
|*-Liaoningornis sensu Zhou and Zhang (not Yanornis+)
`--+--"Archaeorhynchus"
`--+--Yanornis
|*-Guildavis (not a neornithine)
`--+--Yixianornis
|*-Gansus (not Iaceornis+)
`--+--Apsaravis
|*-Ambiortus (not Hesperornithes+)
`--+--Songlingornis
`--+--+--Baptornis
| `--Hesperornis
`--+--Ichthyornis
`--+--Limenavis
|*-Apatornis (not a neornithine)
`--+--Iaceornis
`--+--+--Lithornis
| `--Crypturellus
`--+--+--Chauna
| `--Anas
`--+--Gallus
`--Crax
The first odd thing about the tree is that a Sauriurae of sorts is formed by
Confuciusornis, Chaoyangia and enantiornithines (including Vorona). It's
supported by- dorsal centra much longer than wide; deltopectoral crest
projected dorsally; deltopectoral crest subequal to shaft in width;
proximoposterior surface of deltopectoral crest concave; m.
humerotricipitalis groove on humerus; brachial scar on ulna; anterior
surface of metacarpal I broadly convex; proximodorsal ischial process
contacts ilium; enlarged posterior trochanter; fibular trochlea laterally
projected as small notch; tuberositas retinaculiextensoris present on
proximal tarsus; one proximal vascular foramen on tarsometatarsus; m.
tibialis cranialis tubercle on metatarsal II. Enforcing ornithothoracine
monophyly is just one step longer. When this is done, Vorona can be a
confuciusornithid, enantiornithine or euornithine basal to Patagopteryx.
Liaoningornis can have two positions, depending on whose codings I use.
As coded by Clarke, it's an enantiornithine sister to Vorona. This is based
on- sternal keel projected (also in ornithuromorphs; coded absent by Zhou
and Zhang); reduced interclavicular angle (also in ornithuromorphs; coded ?
by Zhou and Zhang); elongate hyocleidium (coded ? by Zhou and Zhang);
unfused scapulocoracoid (also in ornithuromorphs; coded ? by Zhou and
Zhang); radius with deep longitudinal groove (also in yanornithids); distal
metatarsal fusion (also in ornithuromorphs); ginglymoid metatarsal II (coded
absent by Zhou and Zhang; also in Patagopteryx).
As coded by Zhou and Zhang, it's a basal ornithuromorph, in a polytomy with
Hongshanornis, "Archaeorhynchus" and more derived birds. This is based on-
sternal keel extends anteriorly (coded absent by Clark; also present in
Neuquenornis); radius with deep longitudinal groove (only shared with
yanornithids; also in enantiornithines); medial cnemial crest (coded absent
by Clarke); narrow intercondylar groove on astragalus (coded ? by Clarke;
only shared with Apsaravis and Yanornis; also in enantiornithines); distal
metatarsal fusion (also in Vorona); metatarsal V absent (also in some
enantiornithines; coded ? by Clarke); hypotarsus present (coded ? by
Clarke).
So its position in Clarke's version is primarily due to the elongate
hypocleidium which was uncoded by Zhou and Zhang (interpreted as the
anterior sternal keel?), and the ginglymoid metatarsal II which was coded
differently by Zhou and Zhang (stated and illustrated as present in original
description). While its position in Zhou and Zhang's version is due to the
anteriorly extended sternal keel, medial cnemial crest and hypotarsus, which
were coded as absent (said to be poorly preserved, and seemingly in part
interpreted as a hypocleidium), absent (the original desiption notes a small
bone similar to the lateral and medial cnemial crests) and unknown
respectively by Clarke. Thus it's really a matter of coding disagreements.
When Liaoningornis is excluded, the only difference is that a polytomy forms
between Confuciusornis, Vorona, enantiornithines and ornithuromorphs.
Examination of the trees indicates both Sauriurae and Ornithothoraces are
possible. Making a new Liaoningornis OTU using only the codings which agree
between authors results in it being able to go anywhere inside Pygostylia
(which is unresolved like when Liaoningornis is excluded) basal to
Apsaravis. Using Clarke's codings (which I subjectively trust more) and
constraining Ornithothoraces, Liaoningornis can be an enantiornithine or
euornithine less derived than Hongshanornis. I myself find its sternal
shape to be intriguingly similar to Eoalulavis, arguing for the
enantiornithine identification.
Hongshanornis is resolved as an ornithuromorph more derived than
Patagopteryx, so is not the most basal known, contra Zhou and Zhang.
Perhaps that's why they excluded it from their analysis. This is based on-
jugal-postorbital contact absent (unknown in Patagopteryx); shortened
pygostyle (unknown in Patagopteryx); ossified uncinate processes (unknown in
Patagopteryx); procoracoid process; humeral head convex in anterior view;
midline of humeral head projected furthest proximally (unknown in
Patagopteryx, and quite possibly correlated with the previous character);
manual phalanx II-1 strongly compressed; proximodorsal ischial process
absent; tibiotarsal condyles subequal in transverse width.
"Archaeorhynchus" is more derived than Hongshanornis based on- pneumatic
articular (unknown in Hongshanornis); reduced caudal zygapophyses (unknown
in Hongshanornis); sternal carina extends anteriorly (unknown in
Hongshanornis); hypocleidium absent; lateral coracoid process; ulnohumeral
ratio ~100; metacarpal III reduced in width compared to metacarpal II;
medial cnemial crest (unknown in Hongshanornis); tarsometatarsal proximal
vascular foramina absent (unknown in Hongshanornis; only shared with
Yanornis and Yixianornis). Some local autapomorphies of the taxon include
small nares, a noncondylar quadrate-quadratojugal articulation, undivided
quadrate head, amphicoelous cervicals, and only seven sacrals. It's also
toothless, presumably where the name originates.
Yanornis is the next most derived taxon, based on- premaxillary, maxillary
and dentary teeth (near certainly primitive, but optimized as derived in
this tree); elongate posterodorsal dentary process; dorsal centra longer
than wide; dorsal pleurofossae (unknown in "Archaeorhynchus" or
Hongshanornis, probably symplesiomorphic for pygostylians); nine or more
sacral vertebrae (also in Patagopteryx, unknown in Hongshanornis, probably
symplesiomorphic for ornithuromorphs); posterior coracoid surface lacks
fossa (unknown in more basal ornithuromorphs, absent in Apsaravis);
acrocoracoid process hooked medially (absent in Apsaravis); transverse
groove on humerus (absent in "Archaeorhynchus", but present in
enantiornithines, so possibly an ornithothoracine symplesiomorphy); distal
humerus compressed anterposteriorly (absent in Patagopteryx, but present in
enantiornithines, so possibly an ornithothoracine symplesiomorphy); deep
longitudinal groove in radius (only shared with Yixianornis); V-shaped
ulnare (absent in Apsaravis); carpometacarpus fused distally (absent in
Hongshanornis, but present in Patagopteryx, so possibly an ornithuromorph
symplesiomorphy); antitrochanter posterodorsal to acetabulum (unknown in
Hongshanornis or "Archaeorhynchus"); distal vascular foramen of metatarsus
closed (absent in "Archaeorhynchus", but present in Patagopteryx, so
possibly an ornithuromorph symplesiomorphy); proximal metatarsal III
displaced plantarily.
Guildavis is at least as derived as Yanornis, but is outside Neornithes.
This is a wider possible distribution than given by Clarke (2004), because
basal ornithuromorphs were more poorly known then.
Next is Yixianornis, which does not come out in Yanornithidae as advocated
by Clarke et al. (2002) and Zhou and Zhang. This is based on- scapula
subequal or longer than humerus; extensor process present; pisiform process
present; pubic foot absent (also in Patagopteryx, though not Yanornis or
"Archaeorhynchus", so maybe an ornithuromorph symplesiomorphy); distal
tibiotarsus with well developed posteroproximally extending crests (unknown
in more basal ornithuromorphs); metatarsal II shorter than IV (also in
Hongshanornis; absent in Apsaravis).
Gansus is at least as derived as Yixianornis, but is not a member of the
Iaceornis + Neornithes clade. Again, this is a wider range than Clarke
(2004) suggested, due to basal ornithuromorph feet being better known now.
Apsaravis is more derived than previous taxa based on- completely
heterocoelous cervical vertebrae; ten or less dorsal vertebrae; at least ten
sacral vertebrae; deltopectoral crest projected dorsally (only shared with
Ambiortus and Ichthyornis); pit on bicipital crest (absent in Yanornis, but
also in enantiornithines, so possibly an ornithothoracine symplesiomorphy);
m. humerotricipitalis groove (also in Confuciusornis and enantiornithines);
ulnar brachial scar (also in Confuciusornis and enantiornithines); radius
with ventroposterior muscle impression (also in "Archaeorhynchus", but not
Yanornis or Yixianornis); metacarpal I distal articulation non-ginglymoid
(also in Yanornis, but not Yixianornis); intermetacarpal process at least
present as scar; obturator flange (also in Patagopteryx); pubis compressed
mediolaterally in section; pubic symphysis absent (also in Patagopteryx);
patellar groove present; tuberositas retinaculiextensoris present on
proximal tarsus; proximal vascular foramen in tarsometatarsus present (also
in Patagopteryx); m. tibialis cranialis tubercle on lateral surface of
metatarsal II.
Ambiortus is at least as derived as Apsaravis, but is not as derived as
Hesperornithes. This agrees with Clarke (2004).
Songlingornis is weakly placed as more derived than Apsaravis based on its
lack of a fused dentary symphysis (which like toothlessness, is probably
optimized incorrectly in this tree).
Finally, sixteen characters support Hesperornithes + Carinatae, thirteen
characters support Carinatae, two place Limenavis more derived than
Ichthyornis, five place Iaceornis more derived than Limenavis, and
twenty-seven support Neornithes. Apatornis is more derived than
Ichthyornis, but is not a neornithine.
Overall, this is the best look at basal ornithuromorph phylogeny yet. It's
complicated by the fact Yixian taxa are more basal than Patagopteryx and
Apsaravis in some ways, yet more derived in others. It's almost as if
Yixian taxa were taking a separate path to get to the ornithurine (sensu
Chiappe) level of specialization. It's almost not surprising Sauriurae
forms when you consider how primitive Hongshanornis and "Archaeorhynchus"
are in many ways. And what does my analysis say? The 90% majority rule
consensus (excluding more basal taxa) is-
|--+--Concornis
| |--Enantiornis
| `--+--+--Eoenantiornis
| | `--LP-4450-IEI
| `--+--+--Eocathayornis
| | `--+--Aberratiodontus
| | `--Jibeinia
| `--+--Sinornis
| `--+--Vescornis
| `--+--Longirostravis
| `--+--Longipteryx
| `--Protopteryx
`--+--+--Eoalulavis
| `--Liaoningornis
`--+--Neuquenornis
`--+--Iberomesornis
`--+--Patagopteryx
`--+--Songlingornis
`--+--Yanornis
`--+--+--Yixianornis
| `--+--Apsaravis
| `--Ambiortus
`--+--Boluochia
`--+--Ichthyornis
`--+--Hesperornithes
`--+--Iaceornis
`--+--Hongshanornis
`--"Archaeorhynchus"
Here Liaoningornis clades with Eoalulavis, though it should be noted I
haven't incorporated Zhou and Zhang's codings for the former. My tree
shares (Patagopteryx (Yanornis (Yixianornis, Apsaravis, Ambiortus
(Hesperornithes, Ichthyornis, Iaceornis)))) with the results above. It
differs in the placement of Songlingornis, but we saw that was weakly
supported above. The placement of Apsaravis and Ambiortus sister to
Yixianornis is a small shift in position, and my tree changes the
interrationships of Hesperornis, Ichthyornis and Iaceornis. The largest
change, however, is the placement of Hongshanornis and "Archaeorhynchus" as
sister to Iaceornis. This is based on the shortened sternum and bowed third
metacarpal (both at least in Hongshanornis), while placing that clade sister
to Hesperornithes is based on the elongate and deep subnarial process,
posteriorly displaced external nares, and absent dorsal jugal process
(again, all are only known for Hongshanornis). None of these characters
were used by Zhou and Zhang. In fact, our character lists are largely
mutually exclusive, mine having many more cranial, axial and manual
characters, while Clarke's has many forelimb and hindlimb characters.
Hongshanornis and "Archaeorhynchus are sister taxa based on their small
external nares, toothless maxilla and dentary, amphicoelous cervicals and
absent extensor process on metacarpal I. These are reversals besides the
toothless elements, which combined with the primitive local autapomorphies
of the taxa (noncondylar quadrate-quadratojugal articulation and seven
sacrals in "Archaeorhynchus"; two phalanges on manual digit III in
Hongshanornis) suggest they are more basal taxa which have developed derived
characters in parallel to the lineage leading to recent birds. I predict
adding more characters to my analysis will demonstrate this for
Hongshanornis, though I hesitate to say much regarding "Archaeorhynchus"
until we have more than a set of codings to go on.
Mickey Mortimer