2015 SVPCA abstract supports troodontid-bird clade

Nice to get confirmation
for a subset of the large reptile tree in a SVPCA poster (Brougham 2015).

From the Brougham results:
“The modified matrix strongly supports a Troodontidae + Avialae clade rather than a monophyletic Deinonychosauria, a topology remarkably convergent on that seen in modified Godefroit phylogeny, in which Aurornis, Eosinopteryx and the Tiaojishan paravians form a sister clade to Anchiornis and more derived avialans, the two of which in turn form a sister clade to Troodontidae.”

Figure 1. Basal theropod subset of the large reptile tree showing troodontids basal to birds and separate from dromaeosaurs.

Figure 1. Basal theropod subset of the large reptile tree showing troodontids (light red) basal to birds (red) and separate from dromaeosaurs (white).

References
Brougham T 2015. Multi-matrix analysis of new Chinese feathered dinosaurs supports troodontid-bird clade. researchgate.net/publication/280728942

Flapping before flight

This is a long overdue and very welcome paper
Many paleontologists of the past thought flight appeared after gliding. This is the so-called trees down theory seen in this PBS video on Microraptor. Others thought the flight stroke appeared while clutching bugs in the air. This is the so-called ground up theory. Through experimentation Ken Dial found out that baby birds armed with only protowings flapped them vigorously to help them climb trees, no matter the angle of incline. Now the kinematics of this wing/leg cooperation are presented in Heers et al. 2016, students of Ken Dial.

Key thoughts from the abstract:
“Juvenile birds, like the first winged dinosaurs, lack many hallmarks of advanced flight capacity. Instead of large wings they have small “protowings”, and instead of robust, interlocking forelimb skeletons their limbs are more gracile and their joints less constrained. Such traits are often thought to preclude extinct theropods from powered flight, yet young birds with similarly rudimentary anatomies flap-run up slopes and even briefly fly, thereby challenging longstanding ideas on skeletal and feather function in the theropod-avian lineage.
For the first time, we use X-ray Reconstruction of Moving Morphology to visualize skeletal movement in developing birds. Our findings reveal that developing chukars (Alectoris chukar) with rudimentary flight apparatuses acquire an “avian” flight stroke early in ontogeny, initially by using their wings and legs cooperatively and, as they acquire flight capacity, counteracting ontogenetic increases in aerodynamic output with greater skeletal channelization.Juvenile birds thereby demonstrate that the initial function of developing wings is to enhance leg performance, and that aerodynamically active, flapping wings might better be viewed as adaptations or exaptations for enhancing leg performance.”
Figure 2. Cosesaurus running and flapping - slow.

Figure 1. Cosesaurus running and flapping – slow.

The same theory
can be applied to the development of wings in fenestrasaurs (Fig. 1) evolving into pterosaurs (Fig 2), as shown several years ago, but does not play a part in the development of flapping wings in bats, which do not walk upright and bipedally.
Quetzalcoatlus running like a lizard prior to takeoff.

Figure 2 Quetzalcoatlus running like a lizard prior to takeoff. Click to animate.

It should be obvious
that competing take-off theories for pterosaurs (Fig. 3) do not take into account this theory on the origin of flapping. Just one more reason not to support the forelimb wing launch hypothesis that has become so popular with ptero-artists recently.

Unsuccessul Pteranodon wing launch based on Habib (2008).

Figure 3. Unsuccessul Pteranodon wing launch based on Habib (2008) in which the initial propulsion was not enough to permit wing unfolding and the first downstroke.

Remember,
getting into the air is difficult if you’ve never done it before. Using both your arms AND your legs to get up speed is a good idea that has worked in the past and in present day laboratories.

References
Heers AM, Baier DB, Jackson BE & Dial  KP 2016. 
Flapping before Flight: High Resolution, Three-Dimensional Skeletal Kinematics of Wings and Legs during Avian Development. PLoS ONE 11(4): e0153446. doi:10.1371/journal.pone.0153446
http: // journals.plos.org/plosone/article?id=10.1371/journal.pone.0153446

The first flightless birds

Yesterday we looked at several early birds (Fig. 1). Earlier we considered the phylogenetic nesting of Balaur (Fig. 2; Csiki Z et al. 2010), which some workers (Cau et al. 2015) considered an early flightless bird.

Figure 7. Bird cladogram with the latest additions. Here the referred specimen of Yanornis nests with enantiornithes while Archaeovolans nests within the Scansoriopterygidae, not with Yanornis.

Figure 7. Bird cladogram with the latest additions. Here the referred specimen of Yanornis nests with enantiornithes while Archaeovolans nests within the Scansoriopterygidae, not with Yanornis.

When determining
the first flightless birds, one must first decide which taxon represents the first or basal bird. In the large reptile tree (subset Fig. 1) the last common ancestor of Enantiornithes and Euornithes is Archaeopteryx siemensi, represented by the Berlin and the Thermopolis specimens. Thus they represent, in this cladogram, the first or basal birds. Both the Enantiornithes and Euornithes produced specimens with a locked down coracoid and expanded sternum, anchors for powerful flight muscles attached to long feathered forelimbs.

Thus the purported first flightless bird,
Balaur, nests outside the bird clade (Fig. 1) established by the large reptile tree.

Figure 1. Balaur compared to various dromaeosaurids and to Sapeornis, both to scale and enlarged for detail. Cau, Brougham and Naish wondered if Balaur was the first neoflightless bird, a sort of dodo of the Cretaceous.

Figure 1. Balaur compared to various dromaeosaurids and to Sapeornis, both to scale and enlarged for detail. Cau, Brougham and Naish wondered if Balaur was the first neoflightless bird, a sort of dodo of the Cretaceous.

Instead
the Scansoriopterygidae produced the first taxa in the Eurornithes with more of a dinosaur/theropod look, with Mei (Early Cretaceous) having the smallest forelimbs relative to the rest of the body in that clade. No doubt it was flightless — and with shorter coracoids and a tiny sternum, reduced its flapping. By contrast, its current sister, Archaeovolans (Fig. 3), retained a robust pectoral girdle and long forelimbs.

Figure 9. Sister taxa at the base of the scansoriopterygidae include Jeholornis, Mei and Archaeovolans, here shown to scale.

Figure 2. Sister taxa at the base of the scansoriopterygidae include Jeholornis, Mei and Archaeovolans, here shown to scale.

As everyone knows,
flightless birds have arisen several times since the Early Cretaceous with Hesperornis and Struthio as examples in the large reptile tree. In evolution everything is gradual and often enough, reversible. And behavior is best determined at the extremes of morphology. More generalized taxa probably had more generalized behavior.

In Dinosaurs of the Air
author Greg Paul Paul “argues provocatively for the idea that the ancestor-descendant relationship between the dinosaurs and birds can on occasion be reversed, and that many dinosaurs were secondarily flightless descendants of creatures we would regard as birds.” According to the large reptile tree, dromaeosaurids and basal troodontids were not birds. But birds are derived troodontids. And troodontids arise from basal dromaeosaurids.

Along these same lines Kavanau 2010 reported
“Varricchio et al. propose that troodontids and oviraptorids were pre-avian and that paternal egg care preceded the origin of birds. On the contrary, unmentioned by them is that abundant paleontological evidence has led several workers to conclude that troodontids and oviraptorids were secondary flightless birds. This evidence ranges from bird-like bodies and bone designs, adapted for climbing, perching, gliding, and ultimately flight, to relatively large, highly developed brains, poor sense of smell, and their feeding habits.” Not so, according to the large reptile tree. But, to their point, bird-like theropods have arisen about 8 times by convergence, as we looked at earlier here.

References
Cau A, Brougham T and Naish D. 2015. The Phylogenetic Affinities of the Bizarre Late Cretaceous Romanian Theropod Balaur bondoc (Dinosauria, Maniraptora): Dromaeosaurid or Flightless Bird? PeerJ. 3: E1032. DOI: dx.doi.org/10.7717/peerj.1032
Csiki Z, Vremir M, Brusatte SL, Norell MA 2010. An aberrant island-dwelling theropod dinosaur from the Late Cretaceous of Romania. Proceedings of the National Academy of Sciences of the United States of America 107 (35): 15357–15361.
Kavanau JL 2010. Secondarily flightless birds or Cretaceous non-avian theropods? Med Hypotheses 74(2):275-6.
Paul G 2002. Dinosaurs of the Air: The Evolution and Loss of Flight in Dinosaurs and Birds. Johns Hopkins University Press, Baltimore, 472 pp.

wiki/Balaur_bondoc

newslink on secondarily flightless bird Epidexoptryx.

A fresh look back at the ‘Archaeoraptor’ scandal

Earlier we looked at the ‘Archaeoraptor’ scandal under the heading “chimaeras and fakes.” Here we’ll start with a short history, then consider new discoveries and cladograms.

Figure 1. 'Archaeoraptor' in UV light from a page spread in National Geographic. When this was published it was big news.

Figure 1. ‘Archaeoraptor’ in UV light from a page spread in National Geographic. When this was published it was big news. Now such specimens have become more commonplace.


In July 1997
an unidentified Chinese farmer uncovered a rare (at that time) Early Cretaceous dinosaur with feathers (Fig. 1). During collection the plate on which the dinosaur was preserved cracked apart into a dozen or so pieces (Fig. 2). These were cemented together, but lacked feet and a tail. Nearby, from the same locality, a ‘suitable’ set of feet and tail were cemented to the plate to create a complete presentation. A year later the fossil was sold to an unidentified dealer and smuggled into the United States.

In February 1999
the feathered fossil was on display at the Tucson Gem and Mineral Show where it was purchased by The Dinosaur Museum in Blanding, Utah, USA. Artists, Stephen and Sylvia Czerkas ran the museum. A board member provided the $80,000 purchase price. Paleontologists Phil Currie and Xu Xing agreed to study the fossil.

In March 1999
Currie noticed the left and right feet (pedes) were identical: part and counterpart. ‘Improvements’ like this happen more often than one would wish with fossils that are purchased from dealers rather than extricated from a site by museum led expeditions.

Figure 1. Archaeoraptor from Rowe et al. 2000. Colored areas indicate different sources for matrix and fossils there in.

Figure 2. Archaeoraptor from Rowe et al. 2000. Colored areas indicate different sources for matrix and fossils there in.

In July 1999
CT scans were made of the fossil (Rowe et al. 2001, Fig. 2). These indicated that the bottom fragments were not part of the upper fossil, but that news did not get out until later.

In August 1999
authors Czerkas, Currie, Rowe and Xu submitted a paper to Nature on the fossil, noting that the legs and tail were composited into the slab. Nature rejected the paper. Shortly thereafter Science rejected the paper, with referees noting the illegal purchase and doctoring of the fossil.

In September 1999
Currie’s preparator concluded the fossil was a composite of 3 to 5 specimens. Again that news did not get out until later.

In October 1999
National Geographic Magazine held a press conference at which they unveiled the fossil  informally named, “Archaeoraptor,” and announced it as a transitional fossil between birds and non-bird theropod dinosaurs (which it is not, see below). Plans were also announced to return the illegally exported fossil to China.

The November 1999 issue of Nat Geo
featured the fossil in an article about dinosaur feathers (Sloan 1999, Fig. 1). Bird expert Storrs Olson criticized the pre-naming of any fossil in a popular publication without proper peer review in an academic publication. Nobody was able to ‘stop the presses’ at Nat Geo.

In December 1999 Xu Xing
sent emails to Sloan and others announcing he had found the counterpart for the tail of ‘Archaeoraptor’, but it belonged to another genus, a microraptor. Perhaps a bit to harshly, Xu Xing labeled the Nat Geo specimen a ‘fake.’

In February 2000 Nat Geo issued a press release
stating an investigation had begun and indicating the fossil may be a chimaera or a composite, something museums create. or at least used to create, on a regular basis.

In March 2000 Nat Geo published 
the forum letter from paleontologists Xu Xing suggesting that the tail did not match the rest of the body. The word ‘fake’ was replaced with ‘composite’ by the editors. And that seems  appropriate.

In April 2000 Stephen Czerkas
admitted his mistake. Others involved also expressed regret.

In October 2000 Nat Geo published 
the results of their investigation (Simmons 2000), concluding that the fossil was a composite and that most of the pertinent parties had made some mistakes.

In March 2001 Nature published
a short paper by Rowe et al. (2001) who reported on the evidence from the CT scans. They concluded that the top part was a single specimen. A second part provided the left femur, a third both tibiae, a fourth both feet and a fifth separate specimen provided the tail.

Now, here’s where it gets interesting…

In August 2002
Czerkas and Xu (2002) published an anonymously reviewed description of the fossil, renaming it Archaeovolans (Fig. 3), but it was in a self-published book, not an academic journal.

Figure 3. Archaeoraptor from Czerkas and Xu 2002 along with the original line art tracing and a new color tracing.

Figure 3. Photo of Archaeoraptor from Czerkas and Xu 2002 along with the original line art tracing and a new color tracing. Click to enlarge.

In November 2002
Zhou et al. (2002) reported the majority of the fossil belonged to the established genus Yanornis (Zhou and Zhang 2001, Fig. 4) an euornithine bird nesting basal to Ichthyornis and Hesperornis in the large reptile tree (subset in Fig. 8). Wikipedia likewise reports that Yanornis is an ornithuromorph, the clade that includes all living birds. Similarly, Zhou and Zhang considered Yanornis a member of the Ornithurae.

Figure 4. Yanornis martini holotype (IVPP V12558, Zhou and Zhang 2001) as originally traced and reconstructed by moving those traced lines back to in vivo positions.

Figure 4. Yanornis martini holotype (IVPP V12558, Zhou and Zhang 2001) as originally traced and reconstructed by moving those traced lines back to in vivo positions. This is a euornithine bird with several traits retained by living birds not shared with the STM9-52 specimen (Fig. 6).

I traced
the IVPP V12444 specimen of Archaeoraptor/Archaeovolans/Yanornis (Fig. 3) and created a reconstruction (Fig. 5). I did the same with the STM9-52 specimen assigned (by Zheng et al. 2014) to Yanornis (Fig. 6). The holotype of Yanornis was restored to an in vivo configuration from published tracings in Zhou and Zhang 2001 (Fig. 4). Data from all three were added to the large reptile tree (subset in Fig. 7) for phylogenetic analysis.

Figure 5. Archaevolans reconstruction. Take a look at the in situ hands. In one the metacarpals increase in length laterally. In the other metacarpals and digits 2 and 3 have changed places during taphonomy. The rest of the skeleton is scansoriotpterigid, so I went with the compact metacarpals configuration. Note the procumbent premaxilla teeth, as in Epidexipteryx.

Figure 5. Archaevolans reconstruction. Take a look at the in situ hands. In one the metacarpals increase in length laterally. In the other metacarpals and digits 2 and 3 have changed places during taphonomy. The rest of the skeleton is scansoriotpterigid, so I went with the compact metacarpals configuration. Note the procumbent premaxilla teeth, as in Epidexipteryx.

Rather than lumping all three taxa together
the cladogram split them far apart. So Archaeovolans is not a junior synonym for Yanornis nor is it closely related. Moreover, the STM9-52 specimen referred to Yanornis by Zheng et al. 2014 is not congeneric with it, but nests elsewhere on the tree based on a long list of differences.

Figure 6. Specimen STM9-52 assigned to Yanornis by O'Connor et al. but in the large reptile tree nests instead with Mei in the clade enantiornithes.

Figure 6. Specimen STM9-52 assigned to Yanornis by Zheng et al. 2014, but in the large reptile tree nests instead with the basal enantiornithine, Protopteryx. Note the enormous unfused hands, elongate sternum. lack of a pygostyle and clavicle with a stem.

Perhaps even more interesting
Archaeovolans is phylogenetically bracketed by taxa that have a long bony tail. So the farmer was right — but that didn’t make it right to just pull another one off the shelf.

Figure 7. Bird cladogram with the latest additions. Here the referred specimen of Yanornis nests with enantiornithes while Archaeovolans nests within the Scansoriopterygidae, not with Yanornis.

Figure 7. Bird cladogram subset of the large reptile tree with the latest additions. Here the referred specimen of Yanornis nests with enantiornithes while Archaeovolans nests within the Scansoriopterygidae, not with Yanornis. 

 

The added foot and counter foot
are the right size, but phylogenetically wrong (Fig. 8). The foot and counter foot provided to Archaeovolans have traits found in ornithurine birds, like Yanornis. The correct feet would have had a shorter digit 2, with pedal 2.1 shorter than p2.2, and probably a shorter digit 4.

Figure 8. The foot and counter foot provided to Archaeovolans do not match those of sister taxa but more closely match those of ornithurine birds, like Yanornis.

Figure 8. The foot and counter foot provided to Archaeovolans do not match those of sister taxa but more closely match those of ornithurine birds, like Yanornis. Archaeovolans probably followed the pattern set by its sisters and would have had a relatively shorter digit 2 and digit 4.

According to the large reptile tree
(subset in Fig. 7) the Scansorioterygidae includes at its base the Munich specimen of Archaeopteryx bavarica. Earlier we looked at the need to include several specimens of Archaeopteryx (aka Solnhofen birds) in phylogenetic analysis, because most are distinct from one another and (to my eye) not congeneric. Furthermore, several nest at the bases of the earliest bird clades.

Figure 9. Sister taxa at the base of the scansoriopterygidae include Jeholornis, Mei and Archaeovolans, here shown to scale.

Figure 9. Sister taxa at the base of the scansoriopterygidae include Jeholornis, Mei and Archaeovolans, here shown to scale.Click to enlarge. The tail was reduced in more derived scansoriopterygids, like Epidexipteryx. A relatively small pelvis is shared by all three. 

With these results
Archaeovolans can apparently keep the name that Czerkas and Xu (2002) gave it. The distinction from Yanornis seems pretty obvious. I am surprised that that old paradigm has not been busted yet.

References
Czerkas SA and Xu X 2002. A new toothed bird from China. Pp. 43-60 in Czerkas SJ. ed. 2002. Feathered Dinosaurs and the Origin of Flight. The Dinosaur Museum Journal 1. Blanding, Utah, USA.
Simons LM 2000.
 Archaeoraptor Fossil Trail. National Geographic 198 (4): 128–132.
Sloan CP 1999. Feathers for T. rex?. National Geographic 196 (5): 98–107.
Zheng X, O’Connor JK, Huchzermeyer F, Wang X, Wang Y, Zhang X, et al. 2014. New Specimens of Yanornis Indicate a Piscivorous Diet and Modern Alimentary Canal. PLoS ONE 9(4): e95036. doi:10.1371/journal.pone.0095036
Zhou Z, Clarke JA and Zhang F-C 2002. Archaeoraptor’s better half. Nature Vol. 420: 285.
Zhou Z. and Zhang F. 2001. Two new ornithurine birds from the Early Cretaceous of western Liaoning, China. Chinese Science Bulletin, 46 (15), 1258-1264.

 

Sometimes it takes the paleo crowd an ‘epoch’ to accept new data

A few short bios here demonstrate 
that paleontology often takes a lonnnggg time to accept data, break with paradigm and adopt new hypotheses. Judge for yourself whether this is due to data, peer pressure, public opinion, inertia, fear, pride, being too busy or what have you.

Thomas Henry Huxley
In the 1860s TH Huxley proposed a relationship between birds and dinosaurs. According to Wikipedia: “Huxley had little formal schooling and was virtually self-taught. He became perhaps the finest comparative anatomist of the latter 19th century. After comparing Archaeopteryx with Compsognathus, he concluded that birds evolved from small carnivorous dinosaurs, a theory widely accepted today.” But not back then.

“Darwin’s ideas and Huxley’s controversies gave rise to many cartoons and satires (cartoon attacks continue in the present day). It was the debate about man’s place in nature that roused such widespread comment: cartoons are so numerous as to be almost impossible to count.”

“Although Huxley was opposed by the very influential Owen, his conclusions were accepted by many biologists, including Baron Franz Nopcsa (that’s good to know!)while others, notably Harry Seeley, argued that the similarities were due to convergent evolution. After the work of Heilmann, the absence of clavicles in dinosaurs became the orthodox view despite the discovery of clavicles in the primitive theropod Segisaurus in 1936. The next report of clavicles in a dinosaur was in a Russian article in 1983.” Even so, that paradigm was not broken for another 17 years. See below.

John Ostrom
According to Wikipedia, “Ostron, revolutionized modern understanding of dinosaurs in the 1960s. His 1964 discovery of Deinonychus is considered one of the most important fossil finds in history. The first of Ostrom’s broad-based reviews of the osteology and phylogeny of the primitive bird Archaeopteryx appeared in 1976.” That’s his legacy. However, his life, as he lived it, was apparently something different and something we can all empathize with.

According to the Hartford Courant (2000), “In 1973, Ostrom broke from the scientific mainstream by reviving a Victorian-era hypothesis (see above) that his colleagues considered far-fetched: Birds, he said, evolved from dinosaurs. And he spent the rest of his career trying to prove it.” With the announcement of the first dinosaurs with feathers from China, Ostrom (then age 73) was in no mood to celebrate. He is quoted as saying, ““I’ve been saying the same damn thing since 1973, `I said, `Look at Archaeopteryx!'” Ostrom was the first scientist to collect physical evidence for the theory. Ostrom provoked a debate that raged for decades. “At first they said, `Oh John, you’re crazy,”’ Ostrom said in 1999.

Robert Bakker
Wikipedia reports, “One alternate hypothesis challenging Seeley’s classification (the dichotomy of Saurischia/Ornithisichia) was proposed by Robert T. Bakker in his 1986 book The Dinosaur Heresies. Bakker’s classification separated the theropods into their own group and placed the two groups of herbivorous dinosaurs (the sauropodomorphs and ornithischians) together in a separate group he named the Phytodinosauria (“plant dinosaurs”). The Phytodinosauria hypothesis was based partly on the supposed link between ornithischians and prosauropods, and the idea that the former had evolved directly from the later, possibly by way of an enigmatic family that seemed to possess characters of both groups, the segnosaurs. However, it was later found that segnosaurs were actually an unusual type of herbivorous theropod saurischian closely related to birds, and the Phytodinosauria hypothesis fell out of favor.” Yes, the segnosaurs are indeed derived theropods, but the Phytodinosauria is recovered in the large reptile tree. Click here for a supporting opinion (not supported by a cladogram).

There are several hundred daily readers of this blog
Many read it because they hate it. Others because they find something interesting enough here to keep coming back. Still others drop in to see what’s up only when something big or controversial comes around.

Only every so often
does the world of paleontology comes around to agree with conclusions first found here. The ‘Eoraptor as a phytodinosaur’ hypothesis comes to mind as an example.

On the other hand,
I’ve noticed if I have anything to do with a hypothesis (pterosaur origins, reptile origins, dinosaur origins, etc.), others completely avoid the taxa, avoid the hypothesis and to top it off, Hone and Benton (2009) went so far as to attribute my published work to another worker after earlier (Hone and Benton 2007) making the correct attribution. It can be crazy out there. Not sure why…

Perhaps there is a reason for this conservatism
As readers have seen here on many, many occasions, a long list of paleontologists have come up with incorrect hypotheses, especially in the realm of systematics. As has been demonstrated, much of this is due to relying on old matrices, inappropriate taxon exclusion and inclusion, problems minimized with a large gamut study like the large reptile tree. But that is something that most paleontologists are currently loathe to accept or even test. Then again…

Conspicuous by its absence, Cartorhynchus was excluded from Ji et al. 2016.
Earlier we looked at a new ichthyosaur cladogram by Ji et al. 2016. Yesterday it crossed my mind that the cladogram did not include the Early Triassic Cartorhynchus, which Motani et al. 2014 considered a strange “basal ichthyosauriform.” Earlier here and here we nested Cartorhynchus as a basal sauropterygian/ pachypleurosaur. Montani, Ji and Rieppel were coauthors on both studies. So that team was aware of Cartorhynchus and two years had passed since publication. So, what happened? I can only wonder if the large reptile tree had some influence.

References
Ji C, Jiang D-Y, Motani R, Rieppel O, Hao W-C and Sun Z-Y 2016. Phylogeny of the Ichthyopterygia incorporating recent discoveries from South China. Journal of Vertebrate Paleontology 36(1):e1025956. doi: http://dx.doi.org/10.1080/02724634.2015.1025956
Motani R, Jiang D-Y, Chen G-B, Tintori A, Rieppel O, Ji C and Huang D 2014. A basal ichthyosauriform with a short snout from the Lower Triassic of China. Nature doi:10.1038/nature13866

wiki/Cartorhynchus

 

Sapeornis vs. Balaur

Sapeornis (Fig. 1) was a basal bird that retained teeth, but had a short tail with a pygostyle and had large wings. It was certainly flapping and flying. Earlier we nested Sapeornis between Chiappeavis and all higher birds, including all extant birds.

Yesterday the reported link between Sapeornis and Omnivoropteryx was snipped. The latter is a scansoropterygid bird. Workers, it appears, occasionally like to compare Sapeornis to novel fossils, even when comparisons are not warranted.

When the ‘bizarre’ dromaeosaur with double killer claws
Balaur (Csiki et al. 2010), was reexamined by Cau, Brougham and Naish 2015, one of their results nested Balaur with Sapeornis (Figs. 1, 2).

Figure 1. Balaur compared to various dromaeosaurids and to Sapeornis, both to scale and enlarged for detail. Cau, Brougham and Naish wondered if Balaur was the first neoflightless bird, a sort of dodo of the Cretaceous.

Figure 1. Balaur compared to various dromaeosaurids and to Sapeornis, both to scale and enlarged for detail. Cau, Brougham and Naish wondered if Balaur was the first neoflightless bird. A casual glance finds many similarities, but analysis sets the record straight.

Thus, Cau, Brougham and Naish 2015,
and later Naish’s own blog post, wondered if Balaur was the first flightless bird. They nested it after Archaeopteryx (Fig. 2). By contrast, in the large reptile tree, Balaur nests where both Csiki et al. (2010) and Brusatte et al. (2013) nested it: with dromaeosaurs. On a reduced list of traits (Balaur lacks a skull) shifting Balaur over to Sapeornis adds 12 steps, which is not a large number considering the number of intervening taxa (12 nodes).

Figure 2 The Cau et al tree based on the Brusatte et al. tree. Note the nesting of Balaur among long-tailed post-Archaeopteryx birds, but a sister to Sapeornis, which has a pygostyle. Click to enlarge. 

Figure 2 The Cau et al tree based on the Brusatte et al. tree. Note the nesting of Balaur among long-tailed post-Archaeopteryx birds, but a sister to Sapeornis, which has a pygostyle. Click to enlarge.

Naish notes (pro-dromaeosaurid):

  1. This dromaeosaurid interpretation of Balaur looks reasonable on the basis of the animal’s size and foot anatomy, and Balaur is certainly dromaeosaurid-like in a general sense.

Naish notes (pro-avian):

  1. “Balaur is anatomically weird when interpreted as a dromaeosaurid,
  2. Balaur is likely not a dromaeosaurid, but a secondarily flightless bird.
  3. It has a reduced third finger (lacking a claw),
  4. extensive fusion between the hand and wrist bones,
  5. a strangely broad, extensively fused pelvis with pubic bones that bow outwards for most of their length and are strongly swept back,
  6. fusion between the tibia and fibula,
  7. fusion between the tibia and ankle bones,
  8. an especially stocky, heavily built, partially fused-up foot
  9. and a long hallux (first toe) with an especially big claw.
  10. “All of the features I just mentioned – yes, all of them – are present in Avialae,”
  11. In addition, the manual unguals of Balaur are not as strongly curved as those of most dromaeosaurids
  12. the flexor tubercles (the bony lumps on the undersides of the unguals that anchor ligaments used in ungual flexion) are comparatively weakly developed, thus Balaur was in possession of a non-raptorial hand
  13. Godefroit et al. (2013), in their description of the Jurassic avialan Aurornis, published a phylogeny where Balaur is an avialan, closer to Pygostylia (the short-tailed bird clade) than is Archaeopteryx.
  14. And Foth et al. (2014), in their study of a new Archaeopteryx specimen, also found Balaur to be a member of Avialae, again closer to crown-birds than Archaeopteryx.”

The large reptile tree notes

  1.  if Balaur is avian purported avian sister taxa are all a magnitude smaller
  2. and developing larger wings, not smaller ones.
  3. the pes of Balaur is robust, not bird-like in general proportions or morphology.
  4. the non-raptorial manus and larger gut of Balaur (based on the wider pubis) suggests herbivory or omnivory. That alone would make it bizarre among dromaeosaurs, but not so bizarre among theropods.
  5. Balaur fuses the scapulocoracoid. Sapeornis does not.
  6. Balaur has a four-part sternum, like other dromaeosaurids. Sapeornis lacks a sternum, but sister taxa have a single sternum.
  7. Balaur has a large olecranon process. Sapeornis does not.
  8. Balaur has a subequal manus and pes. Sapeornis has a larger manus.
  9. Balaur has a smaller humerus than tibia. Sapeornis has a larger humerus.
  10. Balaur aligns mc2-3 with m1.1. Sapeornis aligns mc2-3 beyond m1.1
  11. Balaur mc2 is the longest. Sapeornis mc2=mc3.
  12. Balaur metatarsus is shorter than half the tibia. Sapeornis, not shorter
  13. Balaur aligns mt2-3 with mt1. Sapeornis aligns p1.1 IF rotated anteriorly, but it is rotated posteriorly.
  14. Balaur has one phalanx on mt5. Sapeornis has three.
  15. Balaur is larger than 60 cm long. Sapeornis is not.

Plus

  1. Balaur fuses distal tarsals to metatarsals. So does Velociraptor. Not Sapeornis or Chiappeavis.
  2. Balaur retains standard anterior caudal vertebrae. Sapeornis compresses them as part of a pygostyle morphology.
  3. Balaur does not have a bird-like expanded deltopectoral crest. Sapeornis does.
  4. Balaur does not retain any traits which would indicate that its ancestors were small, perching, flapping birds like Archaeopteryx and Sapeornis.

Sure, Balaur is a bizarre dromaeosaur. 
It might even be an herbivore. But those traits listed by Naish must be considered convergent with one bird or another, because they are not all found in one tested bird (like Sapeornis). The large reptile tree does not nest Balaur outside of the dromaeosaurs with present data. Birds have bowed pubes because they have enlarged air sacs. Ultimately bird pubes separate distally to accommodate even larger air sacs. That’s not the case with bulky Balaur. As a scientist, Naish should have thought about that and the following dromaeosaur synapomorphies shared with Balaur before suggesting that Balaur was a sister to the bird Sapeornis.

Unlike birds, Balaur has

  1. a four-part sternum, like other dromaeosaurs.
  2. a killer claw,  like other dromaeosaurs.
  3. an anteriorly-directed pedal digit 1, like other dromaeosaurs.
  4. is goose sized, like other dromaeoaurs.
  5. robust pedal bones, like other dromaeosaurs.
  6. smaller fore limbs than hind limbs, like other dromaeosaurs.
  7. deep, robust dorsal vertebrae, like other dromaeosaurs.

Naish should have listened to himself 
when he wrote, Balaur is certainly dromaeosaurid-like in a general sense.” 

Naish saw the specimens first hand.
I did not. Naish did not create his phylogenetic matrix first hand. I did. Naish did not include various specimens of Archaeopteryx as ITU (individual taxonomic units). I did. Naish did not put reconstructions of the two taxa, Balaur and Sapeornis, next to one another and next to competing candidates for a final check. I did. It’s good practice.

When someone is trying to prove a point,
whether valid or not, they generally don’t weigh all aspects evenly. They try to prove their point. We’ve seen Naish do this before with tragic consequences to his own reputation. I don’t think Naish and his team weighed all aspects of Balaur evenly. If Balaur really did nest between Archaeopteryx (but which one?) and Sapeornis, then it really should have looked like one or the other or an amalgam of both. Instead, it’s just one more example of an ‘strange bedfellow’ that actually nests elsewhere when tested on the large reptile tree.

Comments made above
should have been made by the manuscript referees. Some are listed in the acknowledgements to the paper. Critical thinking seems to be fading in paleontology. That’s why this blog exists.

One should never trust anyone’s interpretations,
observations or cladistic analyses, especially if things don’t look right. Instead, one should repeat the observation, experiment or analysis for oneself. That’s what I do here. As you already know, if something doesn’t look right, it probably isn’t. We’ve seen paleo-oddities paraded before that are not so odd after all when properly nested.

References
Brusatte, et al. 2013. The osteology of Balaur bondoc, an island-dwelling dromaeosaurid (Dinosauria: Theropod) from the Late Cretaceous of Romania. Bulletin of the American Museum of Natural History, 374:1-100.
Cau​ A, Brougham​ T and Naish​ D. 2015. The Phylogenetic Affinities of the Bizarre Late Cretaceous Romanian Theropod Balaur bondoc (Dinosauria, Maniraptora): Dromaeosaurid or Flightless Bird? PeerJ3: E1032. DOI: dx.doi.org/10.7717/peerj.1032
Csiki Z, Vremir M, Brusatte SL, Norell MA 2010. An aberrant island-dwelling theropod dinosaur from the Late Cretaceous of Romania. Proceedings of the National Academy of Sciences of the United States of America 107 (35): 15357–15361.
Foth C, Tischlinger H and Rauhut, OWM 2014. New specimen of Archaeopteryx provides insights into the evolution of pennaceous feathers. Nature 511, 79-82.
Godefroit P, Cau A., Dong-Yu H., Escuillié F, Wenhao W and Dyke G 2013. A Jurassic avialan dinosaur from China resolves the early phylogenetic history of birds. Nature 498, 359-362.
Lee MSY, Cau A, Naish D, Dyke GJ. 2014. Sustained miniaturization and anatomical innovation in the dinosaurian ancestors of birds. Science 345(6196):562–566 DOI 10.1126/science.1252243.

YouTube video by Wiz Science.

Buitreraptor: not a dromaeosaur, not a sister to Rahonavis

A long-snouted theropod
Buitreraptor gonzalezorum (Makovicky, Apesteguía & Agnolin, 2005, Fig. 1) was recovered as “a near-complete, small dromaeosaurid that is both the most complete and the earliest member of the Maniraptora from South America, and which provides new evidence for a unique Gondwanan lineage of Dromaeosauridae with an origin predating the separation between northern and southern landmasses.”

The authors nested
Buitreraptor between Rahonavis and Austroraptor + Unenlagia distinct from troodontids and traditional dromaeosaurs like Velociraptor

Unfortunately 
the large reptile tree  nests Buitreraptor with the troodontid/pre-birds Aurornis and Anchiornis, two taxa published long after the publication of Buiteraptor. Wikipedia does not make this correction. I was unable to find any prior work linking these taxa.

Figure 1. Buitreraptor skull with bones and missing bones colorized.

Figure 1. Buitreraptor skull with bones and missing bones colorized. That naris is enormous! And fragile! The maxillary fenestra, anterior to the antorbital fenestra, is quite large, lightening the long skull.

By comparison
Aurornis (Fig. 2) also has a large naris and maxillary fenestra, but not nearly as large. Aurornis is Late Jurassic. Buitreraptor is Cenomanian (earliest Late Cretaceous). So that evolutionary chronology makes sense.

Figure 2. Aurornis in several views alongside Archaeoperyx to scale.

Figure 2. Aurornis in several views alongside Archaeoperyx to scale.

Stem like coracoid
Unlike Aurornis, Buitreraptor had an elongated and waisted coracoid, so it is likely that Buitreraptor developped the habit of flapping by convergence with birds, parabirds and pseudo birds.

Rahonavis 
still nests with basal therizinosaurs.

References
Makovicky, PJ, Apesteguía S, Agnolín FL. 2005. The earliest dromaeosaurid theropod from South America. Nature 437: 1007–1011. Bibcode:2005Natur.437.1007Mdoi:10.1038/nature03996PMID 16222297.