When true birds, pre-birds and pseudo-birds first started flapping

Figure 1. Xiaotingia with new pectoral interpretation. See figure 3 for new tracing.

Figure 1. Xiaotingia with new pectoral interpretation. See figure 3 for new tracing. Based on the height of the coracoids, comparable to the height of the furcula, Xiaotingia was an early flapper. Based on the shorter tail length those taller coracoids represent yet another convergence with true birds. 

According to the cladogram
of the large reptile tree the proximal outgroup to Archaeopteryx and the flapping birds includes Eosinopteryx (Godefroit et al. 2013, Middle-Late Jurassic, Tiaojishan Formation, YFGP-T5197, 30 cm, 12 in long) and Xiaotingia (Figs. 1-4; Xu et al. 2011, STM 27-2).  This nesting has not changed despite the addition of several very bird-like theropod taxa recently (some listed below) to the large reptile tree.

Although they both had large wing feathers,
only Xiaotingia had tall coracoids. Coracoids were narrow, but short in Eosinopteryx. Tall coracoids are morphological signs that an extinct taxon was flapping.

Figure 2. Eosinopteryx with new pectoral interpretation. See figure 4 for in situ tracings.

Figure 2. Eosinopteryx with new pectoral interpretation. See figure 4 for in situ tracings. This taxon had smaller coracoids than in Xiaotingia. Based on tail length, this is the plesiomorphic condition.

Tall coracoids first appear
in the true bird lineage with the basalmost Archaeopteryx, the Thermopolis specimen (Fig. 5).

Figure 3. GIF animation of Xiaotingia pectorals showing new interpretations for the coracoid and sternum. Reconstruction in figure 1.

Figure 3. GIF animation of Xiaotingia pectorals showing new interpretations for the coracoid and sternum. Reconstruction in figure 1. The fuzzy yellow and gray drawing is the original published interpretation.  Outlying areas are low rez surrounding higher resolution central area. The difficult to see left coracoid is in green, crushed and scattered. The ventral rim of the right coracoid might be peeking beneath the vertebrae, angled toward the sternum. 

By convergence
and along with Xiaotingia, tall-ish coracoids also appear in the unrelated pseudo bird-like taxa Microraptor + Sinornithosaurus and Velociraptor + Balaur. Evidently they were flapping too.

Figure 4. GIF animation for new interpretation of Eosinopteryx pectoral region. The coracoids appear to be half as long but just as tall as previously interpreted. This is a reduction, as in Cosesaurus, rather than an elongation.

Figure 4. GIF animation for new interpretation of Eosinopteryx pectoral region. The coracoids appear to be half as long but just as tall as previously interpreted. This is a reduction, as in Cosesaurus, rather than an elongation. Reconstructed in figure 2. There were two clavicles hidden in their. The dark green areas may be dermal in origin. 

The Thermopolis specimen
of Archaeopteryx (Fig. 5) has the shortest and smallest coracoids of the Solnhofen birds. Note the basal troodontid (Fig. 7) proportions of the small skull and long tail, distinct from the larger skulls and shorter tails in the clade that includes Xiaotingia and Eosinopteryx.

Figure 1. The six tested Solnhofen birds currently named Archaeopteryx, Jurapteryx and Wellnhoferia.

Figure 1. The six tested Solnhofen birds currently named Archaeopteryx, Jurapteryx and Wellnhoferia.

By contrast and convergence,
and based on the reduction of their coracoids to struts, prevolant pterosaur ancestors, like Cosesaurus (Fig. 6), were flapping millions of generations before this clade had anything resembling wings,

Figure 1. Cosesaurus flapping - fast. There should be a difference in the two speeds. If not, apologies. Also, there should be some bounce in the tail and neck, but that would involve more effort and physics.

Figure 6. Click to enlarge and animate. Cosesaurus flapping – fast. There should be a difference in the two speeds. If not, apologies. Also, there should be some bounce in the tail and neck, but that would involve more effort and physics.

Many workers nest
microraptors and velociraptors closer to birds. At least part of that nesting includes the presence of feathers and tall narrow coracoids, ideal for flapping. Unfortunately these alternate nestings cannot be confirmed by the large reptile tree that nest small troodontids, like Xiaotiingia and Eosinopteryx, basal to birds. At least one prior analysis was riddled with errors. I have not examined others yet.

Figure 1. Sinornithoides youngi figure modified from Russell and Dong 1993.

Figure 7. Sinornithoides youngi figure modified from Russell and Dong 1993. Compare these proportions to the basal Archaeopteryx specimens with their small skulls, short torsos and long tails. 

This is where software comes in handy,
finding most parsimonious trees based on a long list of traits despite convergence in a few traits and making every attempt to keep paradigm and tradition out of every computation. These taxa were reexamined and discovered because the the coracoids did not match while so many other characters do match and nest them together. The coracoids still do not match on sisters Xiaotingia and Eosinopteryx, but several errors were repaired.

References
Godefroit P, Demuynck H, Dyke G, Hu D, Escuillié FO and Claeys P. 2013. Reduced plumage and flight ability of a new Jurassic paravian theropod from China. Nature Communications 4: 1394. doi:10.1038/ncomms2389
Xu X, You H, Du K and HanF-L 2011. An Archaeopteryx-like theropod from China and the origin of Avialae. Nature 475 (7357): 465–470.

 

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Chiappeavis – what is it?

Revised May 11, 2017 with a new look at the ascending process of the prexmaxilla on Chiiappeavis. It’s shorter than I first identified it and I’m happy to correct the error. 

There’s a wonderful new
Early Cretaceous bird out there, Chiappeavis (Figs 1, 2), named for a famous bird paleontologist, Luis Chiappe. The question is, what clade does it belong to?

Figure 1. Chiappeavis nests as an ornithurine bird in the large reptile tree, rather than as an enantiornithine. Click to enlarge. Image from O'Connor et al. 2015. 

Figure 1. Chiappeavis nests as an ornithurine bird in the large reptile tree, rather than as an enantiornithine. Click to enlarge. Image from O’Connor et al. 2015.

From the O’Connor et al. 2016 abstract: The most basal avians Archaeopteryx and Jeholornis have elongate reptilian tails. However, all other birds (Pygostylia) have an abbreviated tail that ends in a fused element called the pygostyle. In extant birds, this is typically associated with a fleshy structure called the rectricial bulb that secures the tail feathers (rectrices). The bulbi rectricium muscle controls the spread of the rectrices during flight. This ability to manipulate tail shape greatly increases flight function. The Jehol avifauna preserves the earliest known pygostylians and a diversity of rectrices. However, no fossil directly elucidates this important skeletal transition. Differences in plumage and pygostyle morphology between clades of Early Cretaceous birds led to the hypothesis that rectricial bulbs co-evolved with the plough-shaped pygostyle of the Ornithuromorpha. A newly discovered pengornithid, Chiappeavis magnapremaxillo gen. et sp. nov., preserves strong evidence that enantiornithines possessed aerodynamic rectricial fans. The consistent co-occurrence of short pygostyle morphology with clear aerodynamic tail fans in the Ornithuromorpha, the Sapeornithiformes, and now the Pengornithidae strongly supports inferences that these features co-evolved with the rectricial bulbs as a “rectricial complex.” Most parsimoniously, rectricial bulbs are plesiomorphic to Pygostylia and were lost in confuciusornithiforms and some enantiornithines, although morphological differences suggest three independent origins.”

Figure 2. Chiappeavis reconstructed. Is this specimen just another Pengornis? The large reptile tree does not nest them together.

Figure 2. Chiappeavis reconstructed. Is this specimen just another Pengornis? The large reptile tree does not nest them together. The wing size alone is enough to distinguish this taxon from Pengornis.

Elsewhere on the Internet, at
Theropoddatabase.blogspot.com, M. Mortimer presents arguments that Chiappeavis is just another Pengornis (Figs. 3, 4).

Figure 3. Pengornis reconstructed not from tracing, but from cutting out the bones and putting them back together. Color tracing is used only for the skull elements. This holotype specimen does not have the same morphology or proportions that Chiappeavis has and it nests within the Enantiornithes.

Figure 3. Pengornis reconstructed not from tracing, but from cutting out the bones and putting them back together. Color tracing is used only for the skull elements. This holotype specimen does not have the same morphology or proportions that Chiappeavis has and it nests within the Enantiornithes with Sulcavis.

Indeed
Chaippeavis nests with enantiornithes birds, close to Pengornis.

Figure 4. Pengornis in situ with tracing from O'Connor et al. identifying bones.

Figure 4. Pengornis in situ with tracing from O’Connor et al. identifying bones.

 

 

 

 

References
O’Connor JK, Wang X-L, Zheng X-T, Hu H, Zhang  X-M and  Zhou Z 2016.
An Enantiornithine with a Fan-Shaped Tail, and the Evolution of the Rectricial Complex in Early Birds.Current Biology (advance online publication) DOI: http://dx.doi.org/10.1016/j.cub.2015.11.036

The hand and super-claw of Drepanosaurus

When Drepanosaurus (Pinna 1980, Figs. 1-3) was first discovered and described, this oddity, metaphorically from the land of Dr. Seuss, presented several never-before-seen morphologies including a hooked tail, humped shoulder, a giant olecranon sesamoid (earlier misidentified as a displaced ulna) and an odd hand with a super-claw on finger two — all on one headless body.

Figure 1. Drepanosaurus featuring fused finger phalanges and a super claw -- among several other odd traits.

Figure 1. Drepanosaurus featuring fused finger phalanges and a super claw — among several other odd traits. This image is updated from a prior attempt. Note: the tips of manual unguals 2-4 are aligned.

After fielding a question,
I told a reader that I would take another look at the Drepanosaurus hand. I’m glad I did. The prior tracing was not based on DGS techniques or high resolution images. This one (Figs. 1-3) is. Earlier I mistakenly reconstructed ungual 2 extending beyond the others. Now I find that the middle three unguals terminated at about the same line (Fig. 3).

Figure 1. Drepanosaurus hand with DGS (digital graphic segregation) techniques used to separate the fingers and discover the vestigial joints in the fused digits. The size and proportions of ungual 1 are guesstimated based on very vague outlines impressed from below on ungual 2. On digit 4 (gold on gold) the original tracing appears to have missed the penultimate phalanx (n dark gold).

Figure 2. In situ tracing using DGS (Photoshop layers) to segregate fingers from one another. The outline of digit 1 (purple) is tentative, based on general patterns and very slight impressions in ungual 2.

Yes
several of the phalanges are apparently fused together. Nevertheless their former joints are still visible and are traced here. The penultimate phalanges are very short, the opposite of most arboreal lizards. The cervicals are also quite short, the opposite of other drepanosaurs.

Why did the phalanges fuse?
Perhaps because that big claw prevented the typical flexion function among phalanx sets. Ungual 2 is so big that several former PILs (now fused phalanges) ran through it.

Figure 2. GIF animation of Drepanosaurus fingers reconstructed and imagined in dorsal view. Metacarpal outlines may not be reconstructed in dorsal view. They are typically arranged with mc4 the longest.

Figure 2. GIF animation of Drepanosaurus fingers reconstructed and imagined in dorsal view from data in figure 2. Metacarpal outlines may not be reconstructed in dorsal view. They are typically arranged with mc4 the longest.

Function?
Like almost all digits, the acted together for grasping. The large size of ungual 2 simply made up for the relative brevity of metacarpal 2 and the proximal phalanges, traits that are plesiomorphic for reptiles. That the extensor surface of the ungual is much larger than the flexor surface suggests that the claws were often held retracted, like cat claws. So these were more like paws, the tendril like arboreal lizard toes. Others have considered drepanosaurs slow movers. I agree.

Unlike earlier chameleon-like hypotheses
for Megalancosaurus, the manual digits of Drepanosaurus appear to have swung through parallel arcs, as in most tetrapods.

In situ
the tall narrow claws lie on their sides, as is typical of ungual preservation in crushed fossils. In figure 3, I imagined them in dorsal view, which is the typical presentation of a manus for other tetrapods. Atypically the ungual extends proximally over the penultimate phalanges in dorsal view. So the transparent colors help to visualize this. One can only imagine the size of the extensor tendons on those hands. The flexors were strong too. Don’t let one of these climb on your arm or hand. You might not ever be able to shake it off.

Phylogeny
Wikipedia reports that Drepanosaurus nests within the Protorosauria, a terrestrial clade or small to large archosauromorphs. In counterpoint, and with actual phylogenetic testing (not tradition), the large reptile tree nests Drepanosaurus and the drepanosaurs with Jesairosaurus and the Keuhneosaurs at the base of the Lepidosauriformes. This clade was arboreal.

References
Pinna G 1980. Drepanosaurus unguicaudatus, nuovo genere e nuova specie di Lepidosauro del trias alpino. atti Soc. It. Sc.Nat. 121:181-192.
Pinna G 1986. On Drepanosaurus unguicaudatus, an upper Triassic lepidosaurian from the Italian Alps. Journal of Paleontology 50(5):1127-1132.
Renesto S 1994. The shoulder girdle and anterior limb of Drepanosaurus unguicaudatus (Reptilia, Neodiapsida) from the upper Triassic (Norian of Northern Italy. Zoological Journal of the Linnean Society 111(3):247-264

wiki/Drepanosaurus

 

Early Evolution of Rhynchosaurs

A new open access paper
by Ezcurra, Montefeltro and Butler 2016 provides several first time ever color photos of rhynchosaur skulls and a cladogram of rhynchosaur relationships (Fig. 1). It’s a good paper, with good interrelationships. Unfortunately the wrong outgroup, the Protorosauria, was chosen.

Figure 1. Rhynchosaur cladogram by Ezcurra et al. 2016. Note the outgroup includes two protorosaurs. The large reptile tree recovers protorosaurs elsewhere and has a long list of outgroup taxa among the trilophosaurs and rhynchocephalians. See figure 2.

Figure 1. Rhynchosaur cladogram by Ezcurra et al. 2016. Note the outgroup includes two protorosaurs. The large reptile tree recovers protorosaurs elsewhere and has a long list of outgroup taxa among the trilophosaurs and rhynchocephalians within the Lepidosauromorpha, not the Archosauromorpha. See figure 2. Carmel area includes taxa matching the large reptile tree among rhynchosaurs and proximal outgroups.

By contrast,
the large reptile tree nests rhynchosaurs with trilophosaurs and rhynchocephalians (sphenodontids, Fig. 2), not protorosaurs. Taxon inclusion will help you recover this relationship, too, if you wish to repeat the experiment. Ezcurra et al. (2016) relied on untested tradition, but that tradition brings with it a certain air of credulity as Prolacerta does indeed converge with Mesosuchus in several regards. But parsimony prevails when the following lepidosauromorphs (Fig. 2) are included in analysis. This is a relationship best left to software, not eyeballs and paradigms.

Figure 2. This subset of the large reptile tree nests rhynchosaurs with trilophosaurs and rhynchocephalians, not protorosaurs.

Figure 2. This subset of the large reptile tree nests rhynchosaurs with trilophosaurs and rhynchocephalians, not protorosaurs. Where is Priosphendon in the Ezcurra study? 

In the transition from rhynchocephalians to rhynchosaurs,
this clade had an interesting radiation that included Leptosaurus, Sapheosaurus, Trilophosaurus and Azendohsaurus (which also nests with protorosaurs when the taxa in figure 2 are excluded, before producing rhynchosaurs. Priosphenodon (Fig. 3), typically considered a Cretaceous rhynchocephalian, is a transitional taxon for some reason left off of the Ezcurra et al. 2016 taxon list that nests closer to rhynchosaurs than Mesosuchus does in the large reptile tree. Probably because all rhynchosaurs died out by the Jurassic.

Figure 3. Priosphenodon nests closer to rhynchosaurs than Mesosuchus does, yet it was not included in the Ezcurra et al. 2016 study.

Figure 3. Priosphenodon nests closer to rhynchosaurs than Mesosuchus does, yet it was not included in the Ezcurra et al. 2016 study. Perhaps because the only known fossils are a hundred million years too late. 

References
Ezcurra MD, Montefeltro F and Butler RJ 2016. The Early Evolution of Rhynchosaurs. Frontiers in Ecology and Evolution 3:142 (23 pgs) doi: 10.3389/fevo.2015.00142 http://dx.doi.org/10.3389/fevo.2015.00142

The troodontid Sinornithoides: finally a taxon nesting that almost matches tradition

Lately
we’ve been having trouble nesting taxa where they have traditionally nested. Earlier we looked at some reasons why that might be so.

Figure 1. Sinornithoides youngi figure modified from Russell and Dong 1993.

Figure 1. Sinornithoides youngi figure modified from Russell and Dong 1993. The skull is tucked under the tail and matrix supporting the gastralia, so it is probably complete, just not exposed. The ‘killer’ toe claw is not so large n this specimen. 

Today
I’m pleased to announce the nesting of Sauronithoides youngi (Russell and Dong 1993, Early Cretaceous, Aptian/Albian, IVPP V9612), about where it nests in other cladograms, between the dromaeosaurids and the pre-birds + birds.

One little problem
In the large reptile tree, however, the order has been shifted around compared to the cladogram of Turner, Makovicky and Norell (2012) in which Anchiornis, Xiaotingia, Jinfengopteryx and Mei nest as basal troodontids, rather that pre-birds and birds, while Sauronithoides nests in a derived node with Troodon. Their cladogram, like the large reptile tree, nests the above named pre-birds closer to birds. The major difference is the separation of dromaeosauridae from the quite similar overall Sauronithoides by a long list of intervening transitional taxa. That can happen in cladistic analysis. Parsimony rules, of course.

Note the further separation
of Velociraptor from Archaeopteryx. If valid, the retroverted pubis developed by convergence in both clades. Intervening and basal taxa have a ventral pubis without a pubic foot. We looked at bird and pre-bird convergence earlier here.

Figure 2. Sinornithoides cladogram. This taxon nests at the base of the pre-birds and birds, derived from the same ancestors as Velociraptor and Balaur.

Figure 2. Sinornithoides cladogram. This taxon nests at the base of the pre-birds and birds, derived from the same ancestors as Velociraptor and Balaur. We’re not getting a clade of troodontids, but a grade of pre-birds here. 

Sinornithoides youngi
 
is one of the most complete troodontid theropod dinosaurs. It was preserved in a bird-like resting posture. In the large reptile tree (632 taxa, Fig. 2) it nests derived from Tanycolagreus and the Velociraptor clade and basal to the pre-birds and birds. Distinct from the predecessor taxa, the rostrum and nares were low, the forelimbs were shorter, the pubis lacked a foot, the pelvis was smaller. Sinornithoides was one of the earlier bird-like dinos to come out of China. It, too, was fossilized in a resting posture with both tail and neck wrapped around its presumably warm-blooded body.

Everything here, of course, is provisional
as are all scientific hypotheses. That the present cladogram (Fig. 2) makes sense in terms of sister taxa appearing similar and of roughly the same size and that predecessors to derived taxa demonstrate a gradually accumulating set of traits I think bodes well for it.

References
Russell D and Dong Z 1993. A nearly complete skeleton of a new troodontid dinosaur from the Early Cretaceous of the Ordos Basin, Inner Mongolia, People’s Republic of China. Canadian Journal of Earth Sciences, 30: 2163-2173.

wiki/Sinornithoides

Mei long: not bird-like, but a real basal flightless bird!

Mei long (IVPP V12733, Xu and Norell 2004, Early Cretaceous, 130 mya, Figs. 1-3) is famous for its 3D preservation in a curled up sleeping posture. Originally considered a young juvenile, bird-like troodontid, Mei long instead nests in the large reptile tree between the Munich specimen of Archaeopteryx BSp 1999 I 50 and Scansoriopteryx along with other scansoriopterygid basal birds. A second specimen, DNHM D2154 (Gao et al. 2012), was also preserved in a sleeping posture.

Troodontidae
Wikipedia reports, “There are multiple possibilities of the genera included in Troodontidae as well as how they are related.” Adding to this problem, in the large reptile tree several taxa sometimes included in the Troodontidae instead nest sequentially basal to birds (Archaeopteryx), not in a single offshoot clade.

Figure 1. Two Mei long specimens, one in vivo, one in situ.  Click to enlarge.

Figure 1. Two Mei long specimens, one in vivo, one in situ.  Click to enlarge.

From Xu and Norell (2004):
“Mei long is distinguishable from all other troodontids on the basis of extremely large nares extending posteriorly over one half of the maxillary tooth row*; closely packed middle maxillary teeth; maxillary tooth row extending posteriorly to the level of the preorbital bar”; a robust, sub-‘U’-shaped furcula*; presence of a lateral process on distal tarsal IV; and the most proximal end of the pubic shaft is significantly compressed anteroposteriorly* and extends laterally just ventral to the articulation with the ilium*.” 

*These happen to be traits found in sister taxa, the Munich Archaeopteryx and/or Scansoriopteryx.

Figure 2. Mei long compared to the BSP 1999 I 50, Munich specimen of Archaeopteryx and Scansoriopteryx to scale. Click to enlarge.

Figure 2. Mei long compared to the BSP 1999 I 50, Munich specimen of Archaeopteryx and Scansoriopteryx to scale. Click to enlarge.

Scansoriopterygids
One branch of basal birds, the scansoriopterygids (Fig. 3), famous for their long third finger, now includes a new sister, Mei long. 

Figure 3.  GIF animation - the skull of Mei long IVPP specimen in situ and reconstructed.

Figure 3.  GIF animation – the skull of Mei long IVPP specimen in situ and reconstructed.

Juvenile?
The orbit is comparatively large in Mei long and several cranial and vertebral features are unfused. Gao et al. 2012 report, “Although the skeleton exhibits several juvenile-like features including free cervical ribs, unfused frontals and nasals, and a short snouted skull, other attributes, full fusion of all neurocentral synostoses and the sacrum, and dense exteriors to cortical bone, suggest a small, mature individual. Microscopic examination of tibia and fibula histology confirms maturity and suggests an individual greater than two years old with slowed growth. Despite being one of the smallest dinosaurs, Mei long exhibits multi-year growth and cortical bone consisting largely of fibro-lamellar tissue marked by lines of arrested growth as in much larger and more basal theropods.”

Distinct from its new sister taxa
Mei has shorter forelimbs and longer hind limbs. It is also a little larger even if not fully grown. Pedal digit 3 is much longer. The sacrum is much wider. The facial bones are much more gracile. The jugal may not have had an ascending process. Some of these are indeed juvenile traits that may have been retained into adulthood. Such fragility may have contributed to its general lack of fusion (less bone, lighter weight, but not for flying despite being (no doubt, but not preserved) fully feathered. Metatarsal 3 appears to be pinched between 2 and 4. Pedal 2.1 is less than half the length of p2.2 and pedal ungual 2 is quite long, but not tightly curved.

Shifting
Mei to any node prior to Archaeopteryx currently and provisionally adds at least 12 steps.

References
Xu X and Norell MA 2004. A new troodontid dinosaur from China with avian-like sleeping posture. Nature 431:838-841.
Gao C, Morschhauser EM, Varricchio DJ, Liu J, Zhao B 2012. Farke AA ed. “A Second Soundly Sleeping Dragon: New Anatomical Details of the Chinese Troodontid Mei long with Implications for Phylogeny and Taphonomy”. PLoS ONE 7 (9): e45203. doi:10.1371/journal.pone.0045203. PMC 3459897. PMID 23028847.

wiki/Mei_(dinosaur)

Another look at Cau et al – part 3

Concerned
that a 10x larger Cau, Brougham and Naish 2015 theropod tree and dataset did not match the theropod subset of the large reptile tree, we examined various problems here and here. Today I conclude with a report of scoring issues in Cau, Brougham and Naish 2015. (Yes, I had a rainy/snowy weekend with nothing more important to do).

The Cau, Brougham and Naish 2015 analysis
includes a very intimidating 1549 characters and 120 taxa. That’s so overwhelmingly huge that it does not invite examination and testing. So, I broke it up. I reexamined only the first 518 characters and I focused on only one taxon that appeared to be mis-nested, LimusaurusCau, Brougham and Naish nested meter long Limusaurus with the giant Majungasaurus (Fig. 1).

Figure 1. Limusaurus and Majungasaurus to scalel.

Figure 1. Limusaurus and Majungasaurus to scale. Cau, Brougham and Naish report these are sisters.

Even at first glance
when you look at Majungasaurus and Limusaurus in vivo, they don’t appear to be sister taxa, as the Cau, Brougham and Naish study recovers. Four aspects of these two taxa appear to unite them: 1) the dorsal vertebrate; 2) the ventrally robust scapula; 3) the tiny forelimb and 4) the four-fingered hand.

The dorsal vertebrae
Unless the Limusaurus specimen has been exposed from the other side of the plate, the dorsal vertebrae are essentially invisible, buried beneath exposed ribs. Nevertheless the Cau, Brougham and Naish study score the dorsal vertebrae of Limusaurus like the Majungasaurus vertebrae.

The scapula and tiny forelimb
Limusaurus and Majungasaurus have a similar scapula that is quite broad ventrally where it meets the coracoid. Such a shape produces similar scapular scores. No one is quite sure why tiny (vestigial) forelimbs sometimes correlate to a robust pectoral girdle, but they do here and in Effigia. The tiny forelimb scores are similar in Limusaurus and Majungasaurus, but these may be due to convergence, as recovered by the large reptile tree, rather than homology, as Cau, Brougham and Naish recover.

Four finger problem
Basal theropods have four metacarpals and sometimes four fingers (1-4), as seen in Majungasaurus. Limusaurus likewise has four fingers, but they are not the same four fingers. In Limusaurus a new medial finger, “finger 0,” lost for millions of years, has reappeared because the hand is essentially an embryo hand. So Limusaurus has fingers 0-3. By not accounting for that difference the Cau, Brougham and Naish study found similar traits in mislabeled digits.

Figure 2. Limusaurus also has four fingers and a scapula with a robust ventral area, like Majungasaurus, but those four fingers are not the same four fingers found in Majungasaurus.

Figure 2. Limusaurus also has four fingers and a scapula with a robust ventral area, like Majungasaurus, but those four fingers are not the same four fingers found in Majungasaurus. Note the many traits Limusaurus shares with Khaan (figure 3).

Other scoring problems 
In the first 518 characters employed by Cau, Brougham and Naish I found dozens of scoring errors surrounding Limusaurus and taxa nesting near it. Nearly all of these tended to and finally did nest Limusaurus with Khaan (Fig. 3), an oviraptorid, with which it shares not only an overall appearance and size, but the detailed scores also match pretty well.

Figure 3. Khaan, an oviraptorid that nests with Limusaurus in the large reptile tree AND the repaired Cau, Brougham and Naish tree.

Figure 3. Khaan, an oviraptorid that nests with Limusaurus in the large reptile tree AND the repaired Cau, Brougham and Naish tree.

Other scoring errors
In the Cau, Brougham and Naish analysis I found scores for invisible traits (i.e. three scores for only two choices). I found a lack of scoring for traits that are visible in certain taxa (i.e. when tooth details were described, there was no option for ‘teeth vestigial or absent,’ so in Limusaurus and Khaan these traits were left unscored). I found scoring for traits that were not exposed in the specimen (example above). I found some traits descriptions to be overly verbose, or just plain confusing (242: “dorsal rib ventral process” — is that the rib itself? or what? If you Google those four words in quotes they cannot be found in the system).

Even simple misspellings
Cau, Brougham and Naish misspelled “length” as “lenght” several times, which reveals that even spellcheck was not used in the character set manuscript. By all such evidence, Cau, Brougham and Naish did not give their character set enough attention.

To their credit
Cau, Brougham and Naish reported on characters that I had never considered before. In the large reptile tree those traits are not necessary to completely resolve the theropods. Some day those traits may be necessary and, if so, I will employ them.

To their discredit
Cau, Brougham and Naish employed ten times as many parsimony informative character traits (1549 vs 151) than were necessary, and still were unable to completely resolve their theropods. There should have been more method and less madness. Once they crossed the threshold of 150 or so characters without resolution (Wiens 2003) they should have looked for errors in their dataset. Hundreds of times I have found that data errors prevent full resolution. And reconstructions help to expose many of those errors.

One of the problems inherent with employing prior datasets
is you tend to inherit whatever errors were already present in that dataset. By accepting and trusting prior data, you avoid testing prior data. And testing prior data is what every good scientist should do. Otherwise you end up with what Cau, Brougham and Naish ended up with.

I examined only a small sample 
of the Cau, Brougham and Naish dataset. It is possible that there are no more errors in that dataset. It is also possible that the rest of their data has a similar, smaller or larger percentage of errors in it than I found in the one small sample.

Let us all hope that no one
employs the Cau, Brogham and Naish 2015 dataset without a thorough going over the data before adding novel taxa and additional characters. Let us all hope that someone someday finds complete resolution in any one of several subsets of the repaired Cau, Brougham and Naish dataset.

By such evidence and methodology
others might have chosen to blackwash every thing that Cau, Brougham and Naish do from this day forward, tarnishing their reputations, as Naish and others have done to ReptileEvolution.com. Blackwashing is never appropriate. Repairs can and should be made whenever and wherever they are discovered.

I will continue to repair my dataset,
as I have always done. That’s good Science.

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
Wiens JJ 2003. Missing data, incomplete taxa, and phylogenetic accuracy. Systematic Biology 52: 528–538.