Tynskya and Messelastur enter the LRT with overlooked bird taxa

Today
two birds enter the LRT, nesting at nodes the experts overlooked. Both were considered closely related members of the clade Messelasturidae. “Initially interpreted as stem-owls, more recent studies have shown that they are actually closely related to modern parrots and are in the same order, Psittaciformes,” according to Wikipedia.

Not true in the LRT.

Backstory #1:
Didunculus, the tooth-billed pigeon (Fig. 1) does not nest in the large reptile tree (LRT, 1807+ taxa) with pigeons or dodos. Instead Didunculus nests with Falco, the falcon, far from pigeons, close to owls, owlets and swifts, something we learned a few years ago.

Figure 2. Figures of the Didunculus skeleton.

Figure 1. Figures of the Didunculus skeleton.

Today’s first bird is
Messelastur (Fig. 2) from the famous middle Eocene Messel pit.

Figure 2. Messelastur skull with colors added.

Figure 2. Messelastur skull with colors added. Note the displaced beak tip and another possible displaced premaxillary bone.

The literature on Messelastur includes:

Peters 1994 (not me) considered Messelastur a member of the Accipitridae (= hawks, eagles, Old World vultures and kin, but not owls). Note the sharp predaceous beak.

Mayr 2005 wrote: “They [Messelasturidae] provide a morphological link between Strigiformes and Falconiformes (diurnal birds of prey), and support the highly disputed falconiform affinities of owls in combining derived tibiotarsus and tarsometatarsus characters of owls with a more plesiomorphic, ‘falcon-’ or ‘hawk-like’, skull morphology.”

Wikipedia 2021 reports, “more recent studies have shown that they are actually closely related to modern parrots and are in the same order, Psittaciformes.” Psittaciformes = parrots (Fig. 3). The Wiki author was citing:

Mayr 2011, who wrote, “If future data strengthen their psittaciform affinities, they not only add a distinctive new taxon to the stem lineage of Psittaciformes, but also show that some stem group Psittaciformes were predatory birds.”

When added to the LRT
Messelastrus nests not with parrots (Fig. 3), but with Didunculus (Fig. 1). Parrots still nest with hoatzins, giant flightless parrots, sparrows and chickens far from hawks, owls and kin.

Figure 3. Skeleton of Ara macao, the scarlet macaw. Note the skeleton has pedal digits 3 and 4 switched.

Figure 3. Skeleton of Ara macao, the scarlet macaw. Note the skeleton has pedal digits 3 and 4 switched.

Backstory #2:
Apus,
the common swift, does not follow tradition and nest with hummingbirds in the LRT. Rather, as we learned several years ago the swift nests with Aegotheles, the owlet, close to owls and other predatory birds.

Figure 2. Apus the common swift is actually a close relative of the falcon and owl, not a hummingbird.

Figure 4. Apus the common swift is actually a close relative of the falcon and owl, not a hummingbird.


Mayr 2000 first described

Tynskya (Fig. 4) an early Eocene Green River bird he considered a link between falcons and owls. In the LRT Tynskya nests with Apus, the swift (Fig. 4), not far from falcons and owls. The skull of Tynskya had huge eyes and a tiny beak, just like Apus, along with hundreds of other aligning traits.

Figure 5. Tynskya in situ and with some parts pulled out for clarity. Apparently the pelvis and backbone are still buried in this ventral view of the torso, dorsal view of the skull after neck torsion.

Figure 5. Tynskya in situ and with some parts pulled out for clarity. Apparently the pelvis and backbone are still buried in this ventral view of the torso, dorsal view of the skull after neck torsion. The ‘x’ marks a broken humerus.The broken sternum is reassembled at lower left.

As you can see,
in both new taxa (above) more closely related taxa were excluded, something the LRT is designed to minimize. Minimizing taxon exclusion will help you nest taxa that display traits convergent with unrelated taxa, like hawks and parrots. Fewer enigmas result, if that’s okay with you. Enigmas and mysteries make paleontology more interesting and intriguing. Unfortunately, the LRT has removed many over the last ten years.


References
Mayr G 2000a. A new raptor-like bird from the Lower Eocene of North America and Europe. Senckenbergiana lethaea 80:59–65.
Mayr G 2005. The postcranial osteology and phylogenetic position of the Middle Eocene Messelastur gratulator Peters, 1994—a morphological link between owls (Strigiformes) and falconiform birds? Journal of Vertebrate Paleontology 25(3):635–645.
Mayr G 2011. Well-preserved new skeleton of the Middle Eocene Messelastur substantiates sister group relationship between Messelasturidae and Halcyornithidae (Aves, ? Pan-Psittaciformes). Journal of Systematic Palaeontology 9(1):159-171.
Peters DS 1994. Messelastur gratulator n. gen. n. spec., ein Greifvogel aus der Grube Messel (Aves: Accipitridae). Courier Forschungsinstitut Senckenberg 170:3–9.

wiki/Accipitridae
wiki/Didunculus
wiki/Tooth-billed_pigeon

The juvenile enantiornithine STM-34-1 nests with Chiappeavis in the LRT

In a paper on Early Cretaceous fossilized feather molting,
O’Connor et al. 2020 presented several specimens, among them an unnamed juvenile STM-34-1 (Figs. 1–3). The specimen originally appeared in part in Zheng et al. 2012 in their study on sternum ontogeny. O’Connor was a co-author then, too.

Figure 1. STM-34-1 in situ along with select elements.

Figure 1. STM-34-1 in situ along with select elements.

Note the shorter forelimb
and longer hind limb in the juvenile, which has no tail feathers preserved as well as those elsewhere on the body and limbs. Birds, like other archosaurs, develop allometrically, changing in shape as they mature. By contrast, pterosaurs, like other lepidosaurs, develop isometrically, not changing in shape as they mature, contra traditional thinking.

Figure 2. STM-34-1 skull in situ and reconstructed.

Figure 2. STM-34-1 skull in situ and reconstructed.

STM 34-1 is from
Liutiaogou, Ningcheng, Chifeng, Inner Mongolia, Lower Cretaceous.

Chiappeavis is from 
Jianchang, Liaoning Province, northeastern China. Jiufotang Formation, Lower Cretaceous

Figure 3. Chiappeavis, Pengornis and STM-34-1 to scale.

Figure 3. Chiappeavis, Pengornis and STM-34-1 to scale.

Added to
the large reptile tree (LRT, 1785+ taxa, subset Fig. 4) STM-34-1 nested with Chiappeavis (Fig. 3).

Figure 4. Subset of the LRT focusing on the bird clade, Enantiornithes.

Figure 4. Subset of the LRT focusing on the bird clade, Enantiornithes.

A phylogenetic analysis that tested STM 34-1
was not presented by O’Connor et al. 2020, nor by Zheng et al. 2012.


References
O’Connor JK, Falk A, Wang M and Zheng X-T 2020.
 First report of immature feathers in juvenile enantiornithines from the Early Cretaceous Jehol avifauna. Vertebrata PalAsiatica 58(1):24–44. DOI: 10.19615/j.cnki.1000-3118.190823
Zheng XT, Wang XL, O’Connor JK et al., 2012. Insight into the early evolution of the avian sternum from juvenile enantiornithines. Nat Commun, 3: 1–8.

wki/Chiappeavis

An even larger genetic study of extant birds in Nature

Feng et al. 2020 bring us
yet another genomic study of extant birds, this time with a circular cladogram so dense it makes no attempt to list the 10,135 bird taxa in this study by dozens of authors.

This was my reply on the study,
copied from the Comments section on the Nature website. The asterisk and double asterisk are how the chicken* and finch** are located on the dense cladogram (their figure 1).

How can one test the validity of genomic studies like this one? Earlier testing by Prum et al. 2015 nested flamingoes (Phoenicopterus) with dissimilar grebes (Aechmophorus) and yardbirds/chickens (Gallus) with dissimilar geese (Anser). Three of these four are not named in the present cladogram which lists and illustrates only a few sample genera. Among these, the genomically distant separation of the phenomically similar finch**, parrot (Agapornis) and chicken* duplicate what was discovered earlier in the Prum et al. 2015 study. Genomic deep time studies too often produce false positives that separate similar taxa and lump dissimilar taxa. By comparison, phenomic studies, like the one online at: http://reptileevolution.com lump similar taxa and separate dissimilar taxa, modeling evolutionary events while including fossil taxa.

Only in phenomic (trait-based) studies can one produce a cladogram in which all related taxa document a gradual accumulation of derived traits modeling actual events. If one is concerned about convergence, adding taxa to phenomic studies overcomes that problem.

Genomic studies have lumped bats with whales (Laurasiatheria) and golden moles with elephants (Afrotheria). Workers have to wake up to the sad fact that genetic studies work in criminal investigations, but not in cladograms.”


References
Feng et al. (dozens of co-authors) 2020. Dense sampling of bird diversity increases power of comparative genomics. Nature 587:252–257.

Darwin’s finches: Mesozoic style

Originally ‘Darwin’s finches’ =
small birds from the Galápagos Islands west of Ecuador, in the Pacific Ocean.

According to Wikipedia:
The term “Darwin’s finches” was first applied by Percy Lowe in 1936, and popularised in 1947 by David Lack in his book Darwin’s Finches. The most important differences between species are in the size and shape of their beaks, which are highly adapted to different food sources.”

For today’s post, metaphorically speaking, ‘Darwin’s finches’ =
“several variations on a last common ancestor restricted to a small geographic area.”

Similar Mesozoic variations
on a last common ancestor restricted to a small geographic area are also documented in the large reptile tree (LRT) and the large pterosaur tree (LPT). Here (Figs. 1–8), other than Late Cretaceous Pteranodon (Fig. 1), and Middle Jurassic Darwinopterus (Fig. 8), the others (Figs. 2–7), are all known from the Late Jurassic Solnhofen Formation, a lagerstätte representing an archipelago or series of islands, much like today’s Galápagos Islands.

Here
(Figs. 1–8) pictures of closely related taxa tell the story of their own evolution much better than any long-winded explanation. No two are alike. Arrows indicate phylogenetic order.

If you want to know more,
click on each of the images below. When taken to the large image pages at ReptileEvolution.com a small link at the top of each page will take you to one of the species pictured therein. Other links to related taxa are posted on each species’ page.

Pteranodon

Figure 2. The DMNH specimen is in color, nesting between the short crest KS specimen and the long crest AMNH specimen.

Figure 1. The DMNH specimen is in color, nesting between the short crest KS specimen and the long crest AMNH specimen. If you see a female in this diagram, let me know. No two are alike.

Rhamphorhynchus

Figure 2. Rhamphorhynchus specimens to scale. The Lauer Collection specimen would precede the Limhoff specimen on the second row.

Figure 2. Rhamphorhynchus specimens to scale. The Lauer Collection specimen would precede the Limhoff specimen on the second row. No two are alike, but the Vienna specimen is a juvenile of the larger n81 specimen to its right.

Dorygnathus

Figure 8. Click to enlarge. The descendants of Sordes in the Dorygnathus clade and their two clades of pterodactyloid-grade descendants.

Figure 3. Click to enlarge. The descendants of Sordes in the Dorygnathus clade and their two clades of pterodactyloid-grade descendants. No two are alike.

Germanodactylus

Germanodactylus and kin

Figure 4. Click to enlarge. Germanodactylus and kin. No two are alike.

Pterodactylus

The Pterodactylus lineage and mislabeled specimens formerly attributed to this "wastebasket" genus

Figure 5. Click to enlarge. The Pterodactylus lineage (in white) and mislabeled specimens formerly attributed to this “wastebasket” genus (in color boxes). No two are alike.

Scaphognathus

Figure 1. Scaphognathians to scale. Click to enlarge.

Figure 6. Click to enlarge. Only the left three taxa have been identified as Scaphognathus species. Other tiny unnamed specimens are transitional taxa to Pterodactylus or Germanodactylus leading to larger, later taxa. No two are alike.

Archaeopteryx (some of these Solnhofen birds have been renamed)

Figure 3. Several Solnhofen birds, including Archaeopteryx, compared to Ostromia to scale.

Figure 7. Several Solnhofen birds, including Archaeopteryx, compared to Ostromia to scale. No two are alike.

Darwinopterus

Figure 7. Darwinopterus specimens and a few outgroup taxa.

Figure 8. Darwinopterus specimens and a few outgroup taxa. None of these are basal to any pterodactyloid-grade clades. No two are alike. The female (upper right) is associates with an egg.

Unfortunately,
PhDs and other paleo workers who traditionally refuse to trace and reconstruct ‘to scale’ skeletons of taxa under study never get to discover results like these that are only revealed from producing ‘to scale’ graphics like these (Figs. 1–8). Subtleties come through here, en masse, that are lost when looking at individual skeletons in situ one at a time, especially through a microscope, where you don’t get to see ‘the big picture’. Some workers consider such graphics pseudoscience and crankery.

As a result, no other workers
understand or accept the four origins of the pterodactyloid grade arising from phylogenetic miniaturized transitional taxa (Figs. 3, 6) because they omit pertinent tiny and congeneric taxa. Likewise, workers do not yet understand nor accept the radiation of several bird clades having their genesis in Solnhofen basalmost birds. Workers don’t see ‘the big picture’ because of these taxon exclusions.

Rather, too many workers
try to compile a list of specific traits that differentiate one taxon from another. Here we call that, “Pulling a Larry Martin” because it only sometimes leads to greater understanding. The problem is unrelated taxa too often share those same traits by convergence. Here, reconstructions and a confident nesting in the LRT automatically encompass and include ALL the subtle irregularities between taxa that ‘trait seekers’ traditionally overlook.

References

wiki/Darwin’s_finches

Sexual selection: a peacock’s tale

Today’s topic began with a YouTube video
featuring Richard Dawkins and Bret Weinstein (click to view). They discussed the peacock’s elaborate plumage with the idea that peahens were choosing the most magnificent displays. Weinstein opined that it may be more difficult for males to survive with such long trains (= tail feathers folded away, extending posteriorly). Thus females were handicapping their male offspring by selecting peacock mating partners with longer and longer more elaborate tail feathers.

According to Wikipedia:
“The function of the peacock’s elaborate train has been debated for over a century. In the 19th century, Charles Darwin found it a puzzle, hard to explain through ordinary natural selection. His later explanation, sexual selection, is widely but not universally accepted. In the 20th century, Amotz Zahavi argued that the train was a handicap, and that males were honestly signalling their fitness in proportion to the splendour of their trains. Despite extensive study, opinions remain divided on the mechanisms involved.”

Figure 3. Peafowl mating. The males stands crouched upon the back and hips of the female.

Figure 1. Peafowl mating. The males stands crouched upon the back and hips of the female.

Phylogenetically,
in the large reptile tree (LRT, 1735+ taxa) peafowl (genus: Pavo) nest with the common chicken (genus: Gallus). Both are terminal taxa.

At the start, I question:

  1. Do peahens always or often or used to pick the most lavish peacock?
  2. Do peacocks actually compete with each other? Or do most of them give up after sizing up the competition?
  3. Do peacocks mate with as many peahens as they can or do they form pair bonds?
  4. In other words, have we examined the situation enough to know?
  5. Were Dawkins and Weinstein just guessing based on end results?
  6. Added after publication, based on a a reader’s comment: What are the differences between domestic and wild peafowl? (If there are any wild peafowl.)

Summarizing earlier studies, Callaway 2011 wrote:
“Size doesn’t always matter for peacocks. Peahens don’t necessarily choose the males with the biggest tails — but small tails are right out.”

Takahashi et al. 2008 concluded,
“our findings indicate that the peacock’s train (1) is not the universal target of female choice, (2) shows small variance among males across populations and (3) based on current physiological knowledge, does not appear to reliably reflect the male condition.”

Yorzinski et al. 2017 write:
“In species where a male trait is only evaluated by one of the sexes, it is often the males that are assessing the trait, suggesting that male traits often evolve initially in the context of male–male competition, and subsequently, in female choice (Berglund et al., 1996; Borgia and Coleman, 2000). 

Like deer antlers or any other tournament species. Meanwhile, what are the peahens doing?

“We know little about how animals selectively direct their attention during mate and rival assessment. Previous work has shown that female peafowl shift their gaze between potential mates and their environment, potentially scanning for predators and other conspecifics while assessing mates. And, when evaluating a mate, peahens selectively direct their attention toward specific display regions of peacocks. In contrast, we do not know how males selectively alter their attention when assessing other males. (Citations deleted).

“We therefore investigated how males direct their attention when they assess potential rivals, using peacocks as a model system.”

“Competition among peacocks is intense as mating success is highly skewed toward a small proportion of successful males. Males compete with each other by displaying their erect trains or walking parallel to other males. If aggression escalates, they chase each other and engage in fights that consist of them jumping and using their spurs Males with longer trains and tarsi establish territories in central locations within leks and engage in more agonistic behaviors with other males. In contrast, males with shorter trains are less likely to establish display territories (Citations deleted).

“it is clear from these sample periods that males spend a significant fraction of their time monitoring their rivals.

“While assessing their competitors, peacocks did not spend very much time looking at females. In fact, they allocated less than 5%

“Further experiments will be necessary to determine how much time males allocate to monitoring females while they are courting them. We found that when males directed their gaze toward females,

Peacocks also devote a significant amount of their daily time budget to preening (Walther, 2003) and directing attention toward themselves could allow them to monitor the condition of their feathers.

“Similar to the results in this study on peacocks, peahens primarily gazed at the lower display regions of males: at their lower trains, body and legs (Yorzinski et al., 2013).”

Here are a few, short ‘peacocks on display’ YouTube videos 
showing the variation in the use of the display behavior or lack thereof.

Callaway 2011 quotes Petrie (of Petrie and Halliday 1994),
“At the end of the day, we will never know what peahens are looking at and how they select their mates. You can’t ask them.”

Figure 2. Peacock flying.

Figure 2. Peacock flying.

One final thought:
Since predators are likely to attack from the rear of the peacock (video #3 above), what a tiger will get is a mouthful or paw-full of feathers, which can detach under sufficient strain, much like the expendable tail of certain lizards. Thus the hypothesis that a long train of feathers is an impediment to survival in an attack may be true only rarely… which is one reason why peacocks are a relatively successful species, all hypothetical doubts aside.


References
Callaway E 2011. Size doesn’t always matter for peacocks. Nature 1107 online
Dakin R and Mongomerie R 2011. Peahens prefer peacocks displaying more eyespots, but rarely. Animal Behaviour doi:10.1016/j.anbehav.2011.03.016
Petrie M and Halliday T 1994. Experimental and natural changes in the peacock’s (Pavo cristatus) train can affect mating success. Behavioral Ecology and Sociobiology 35, 213-217.
Takahashi M, Arita H, Hiraiwa-Hasegawa M and Hasegqawa T 2008. Peahens do not prefer peacocks with more elaborate trains. Animal Behaviour 75(4):1209–1219.
Yorzinski JL, Patricelli GL, Bykau S and Platt ML 2017. Selective attention in peacocks during assessment of rival males. Journal of Experimental Biology (2017) 220, 1146-1153 doi:10.1242/jeb.150946

wiki/Indian_peafowl
https://www.nature.com/news/2011/110418/full/news.2011.245.html

Shedding new light (literally!) on Jianianhualong: Li et al. 2020

Li et al. 2020 used various frequencies of light
and spectroscope technology on the holotype bones and feathers of Jianianhualong (Figs. 1, 2; Early Cretaceous, Xu et al. 2020, DLXH 1218) to identify specific elements in the matrix and specimen.

From the abstract:
“Here, we carried out a large-area micro-X-Ray fluorescence (micro-XRF) analysis on the holotypic specimen of Jianianhualong tengi via a Brucker M6 Jetstream mobile XRF scanner.”

Figure 2. Jianianhualong, Serikornis and Jurapteryx to scale.

Figure 1a. Jianianhualong, Serikornis and Jurapteryx to scale.

Figure 1. Jianianhualong tengi in situ. This is the largest among the early birds, a fact overlooked by the Xu et al. 2017. Think of Jianianhualong as a giant Archaeopteryx!

Figure 1b. Jianianhualong tengi in situ. This is the largest among the early birds, a fact overlooked by the Xu et al. 2017. Think of Jianianhualong as a giant Archaeopteryx!

From the abstract:
“Jianianhualong tengi is a key taxon for understanding the evolution of pennaceous feathers as well as troodontid theropods, and it is known by only the holotype, which was recovered from the Lower Cretaceous Yixian Formation of western Liaoning, China.” 

What they didn’t do is to rerun their phylogenetic analysis with more taxa (Fig. 2).

What they didn’t do is to create a reconstruction, perhaps using DGS to precisely trace and segregate the bones to rebuild the skeleton (Figs. 1, 3, 4).

Figure 2. Subset of the LRT focusing on Pennaraptora 2014 = Tyrannoraptora 1999. Here Khaan and Velociraptor substitute for Oviraptor and Deinonychus.

Figure x. Subset of the LRT focusing on birds and their ancestors. Jianianhualong nests within Aves (five taxa from the bottom).

By contrast,
in the large reptile tree (LRT, 1730+ taxa) Jianianhualong nests within Aves (five taxa from the bottom of Fig. 2) even though it was clearly not volant due to its much larger size and smaller forelimbs. Close relatives include Archaeopteryx (= Jurapteryx) recurva (= Eichstätt specimen, Fig. 3) and the privately held #11 specimen of Archaeopteryx.

The authors think Jianianhualong is a troodontid.
According to Wikipedia“A number of characteristics allow Jianianhualong to be identified as a member of the Troodontidae. These include:

  1. the long forward-projecting branch and flange of the lacrimal bone; [✓]
  2. the foramina on the nasal bone; [?]
  3. the smooth transition between the eye socket and the backward-projecting branch of the frontal bone; [✓]
  4. the ridge on the forward-projecting branch of the jugal bone; [✓]
  5. the triangular dentary bearing a widening groove; [✓]
  6. the robust forward-projecting branch of the surangular bone; [✓]
  7. the relatively large number of unevenly-distributed teeth; [✓]
  8. the flattened chevrons with blunt forward projections and bifurcated backward projections; [✓]
  9. and the broad and flat “pubic apron” formed by the pubic bones.” [?]
Figure 3. The Eichstätt specimen, Jurapteryx recurva, nests with the living ostrich, Struthio, presently in the LRT.

Figure 2. The Eichstätt specimen, Jurapteryx recurva, nests with the living ostrich, Struthio, presently in the LRT.

Professor Larry Martin would be so proud!
Why? Because the Wikipedia author (above) is using a list of traits to support an hypothesis of interrelationships rather than using a cladogram to support that hypothesis.  Checkmarks [✓] indicate traits Jurapteryx shares. Question marks [?] indicate traits not shown in Jianianhualong or Jurapteryx. Or did I miss something?

The problem is,
various authors add taxa to the Troodontidae that don’t belong there in the LRT, as we learned earlier here. The LRT; subset Fig. x) recovers Jiaianhualong as the largest known member of the Sapeornis/Jurapteryx clade of birds. Several flightless birds are in this clade. These could be confused with troodontids for that reason. In the LRT the clade Troodontidae include Sinornithoides + Sauronithoides their LCA and all derived taxa. None of these are direct bird ancestors.

Getting back to chemistry
“The bone in Jianianhualong is, as expected rich in calcium and phosphorus, corresponding mineralogically to apatite. The regions where feather remains can be observed show an enrichment and correlation pattern of several elements including manganese, titanium, nickel and copper.”

FIgure 2. GIF animation of the skull of Jianianhualong showing original tracing in line art and colorized bones (DGS) used to create a reconstruction (Fig. 3).

FIgure 3. GIF animation of the skull of Jianianhualong showing original tracing in line art and colorized bones (DGS) used to create a reconstruction (Fig. 3).

Jianianhualong is a troodontid-like bird,
not a bird-like troodontid. Note the odd scapula shape, like that in Sapeornis. Note the retrovered pedal digit 1, showing this taxon was derived from perching birds. The tall naris and long tibia are autapomorphies.

Xu et al. 2014 made a headline out of
the asymmetric feathers found with Jianianhualong. In the present context, Jianianhualong is derived from volant ancestors. So asymmetry is expected, not exceptional. This is the earliest known large flightless bird, not an example of the invalid hypothesis of ‘mosaic’ evolution.

Figure 3. Reconstruction of the skull of Jianianhualong based on DGS tracings in figure 2.

Figure 4. Reconstruction of the skull of Jianianhualong based on DGS tracings in figure 2.

Liaoningventor curriei (Shen et al. 2017; DNHM D3012; Early Cretaceous) was also originally described as a non-avian troodontid, but nests with Jianianhualong as a flightless bird.


References
Li J, et al. (8 co-authors 2020. Micro-XRF study of the troodontid dinosaur Jianianhualong tengi reveals new biological and taphonomical signals. bioRxiv 2020.09.07.285833 (preprint) PDF doi: https://doi.org/10.1101/2020.09.07.285833
https://www.biorxiv.org/content/10.1101/2020.09.07.285833v1
Shen C-Z, Zhao B, Gao C-L, Lü J-C and Kundrat 2017. A New Troodontid Dinosaur (Liaoningvenator curriei gen. et sp. nov.) from the Early Cretaceous Yixian Formation in Western Liaoning Province. Acta Geoscientica Sinica 38(3):359-371.
Xu X, Currie P, Pittman M, Xing L, Meng QW-J, Lü J-C, Hu D and Yu C-Y 2017. Mosaic evolution in an asymmetrically feathered troodontid dinosaur with transitional features. Nature Communications DOI: 10.1038/ncomms14972.

wiki/Sapeornis
wiki/Jianianhualong
wiki/Liaoningvenator

“Pulling a Larry Martin” with basal bird pectorals and hands

This is a cautionary tale
The following blog reminds all workers to score the entire specimen if possible, and to score as many more-or-less-complete specimens as possible. Why?

It is of vital importance to use as much data as possible
when scoring each taxon in a phylogenetic analysis to remove any trace of attraction by convergence that happens when just using bits and pieces of cherry-picked taxa.

From Pittman et al. 2020,
“Generally during early avian evolution, the furcula, coracoid, and sternum become more craniocaudally elongate, while the manual digits become reduced and fusion between the metacarpals increases.” 

Not true. In a valid phylogenetic context (Figs. 1–3), like the wide gamut large reptile tree (LRT, 1729+ taxa; subsets Figs. 2, 3), some taxa developed birdy traits quickly while others dawdled or reversed. In this way some bones demonstrated convergence with other less related clades. With this in mind, start with a valid unbiased topology, then let the taxa tell their own story. Avoid the temptation of an easy diagram. Do the necessary work.

Figure 1. Avian furcula aviation from Pittman et al. 2020 and repaired based on LRT results. Let your software decide based on the whole specimen. Convergence is rampant as you can see here.

Figure 1. Avian furcula aviation from Pittman et al. 2020 and repaired based on LRT results. Let your software decide based on the whole specimen. Convergence is rampant as you can see here.

Due to taxon exclusion
Pittman et al. mixed up the order of the pectoral girdles + hands of basal birds (Fig. 1), hoping to tell the story they wanted to tell: gradual evolution. Not only did they skip about a dozen pertinent taxa, they got the order wrong by eyeballing a few traits on cherry-picked taxa.

With more taxa, as in the LRT,
(Figs. 2, 3) the girdles and limbs are phylogenetically re-ordered here (Fig. 1, layer 2 with colors). If Pittman et al. wanted to show gradual evolution, they needed to first establish a valid tree topology by adding more taxa. Instead, by cherry-picking certain traits to show gradual evolution, Pittman et al. were “Pulling a Larry Martin“, putting individual traits on cherry-picked taxa ahead of an entire suite of traits and a wide gamut of taxa.

Figure 2. Subset of the LRT focusing on Pennaraptora 2014 = Tyrannoraptora 1999. Here Khaan and Velociraptor substitute for Oviraptor and Deinonychus.

Figure 2. Subset of the LRT focusing on Pennaraptora 2014 = Tyrannoraptora 1999 = Coelurosauria 1914. Here Khaan and Velociraptor substitute for Oviraptor and Deinonychus.

Figure 2. Subset of the LRT focusing on bird origins. Crown birds and toothed birds are highlighted.

Figure 3. Subset of the LRT focusing on bird origins. Crown birds and toothed birds are highlighted. Figure 2 is slightly more up-to-date, but includes fewer extant birds.

When the phylogenetic order is corrected
based on unbiased results recovered by the LRT (subsets Figs. 2, 3), what seemed to Pittman et al. a gradual transitional series is here revealed to be an example or two of convergence. Note the similarly elongate coracoids on the enantiornithine Parabohaiornis and the unrelated ornithurine, Yanornis (Fig. 1`), derived from an Early Cretaceous sister to a living taxon, Megapodius.

Time after time paleontologists cherry-pick taxa.
That has to stop. Add more taxa and let the software decide the tree topology. Similarly, don’t rely on parts alone (Fig. 1) to illustrate hypotheses, unless they represent taxa already nesting together based on all of their parts and a wide gamut of taxa. Body parts, like hands and girdles, can converge, as they do here.

Figure 3. Mammal tooth evolution alongside odontocete tooth evolution, reversing the earlier addition of cusps.

Figure 4. Mammal tooth evolution alongside odontocete tooth evolution, reversing the earlier addition of cusps.

On a similar note, basal mammal workers
have put too much reliance on tooth traits. Unfortunately, sometimes that’s all they have. If so, what should they do? They should build a tree topology based on complete or more nearly complete specimens. THEN fit it in those tooth and mandible taxa once the tree topology is established in a broader sense, as in the LRT. Earlier (Fig. 4) you saw how odontocete and archaeocete traits brilliantly document a step-by-step reversal to a simple cone shape, like those of basal pelycosaurs. The addition, subtraction and modification of tooth cusps in mammals occurred much more widely than shown by this one example.


References
Pittman M, O’Connor J, Field DJ, Turner AH, Ma W, Makovicky P and Xu X 2020.
Pennaraptoran Systematics. Chapter 1 from Pittman M and Xu X eds. 2020. Pennaraptoran theropod dinosaurs. Past progress and new Frontiers. Bulletin of the American Museum of Natural History 440; 353pp. 58 figures, 46 tables.

https://pterosaurheresies.wordpress.com/2020/08/23/pennaraptora-avoid-this-junior-synonym/

Specimen STM 15-15 of Sapeornis under the laser and DGS

Serrano et al. 2020
used Tom Kaye‘s laser-stimulated fluorescence (LSF) device to reveal more feathers on the STM 15-15 specimen of Sapeornis more clearly than in visible light (Fig. 1). All the glue between the reassembled stones also shows up much more clearly. In this specimen the bones are easier to see in visible light. Under LSF everything organic glows: feathers, bones, guts.

Figure 1. Sapeornis specimen STM-1515, in situ, under laser, under DGS.

Figure 1. Sapeornis specimen STM 15-15, in situ, under laser and under DGS. Ventral view. Here bones are easier to see in visible light, feathers under laser.

From the abstract
“Unseen and difficult-to-see soft tissues of fossil birds revealed by laser-stimulated fluorescence (LSF) shed light on their functional morphology. Here we study a well-preserved specimen of the early pygostylian Sapeornis chaoyangensis under LSF and use the newly observed soft-tissue data to refine previous modeling of its aerial performance and to test its proposed thermal soaring capabilities.”

Figure 2. Sapeornis skull specimen STM 1515

Figure 2. Sapeornis skull specimen STM 15-15

From the discussion
“Our study is the first to use the preserved body outline of a fossil bird—as revealed under LSF—to refine its flight modeling.”

Figure 3. Sapeornis skull, specimen STM 1515.

Figure 3. Sapeornis skull reconsructed —  specimen STM 15-15.

An overlay of colors in Photoshop
(Figs. 1, 2 = digital graphic segregation, DGS) also helps each bone stand out from the matrix. Moreover, the color tracings are used to build a reconstruction (Figs. 3, 4) from which it is easier to compare features, point-by-point with other Sapeornis specimens (Fig. 4).

In this way, character scores are backed up
with visual data for referees and readers to quickly judge whether the contours of every bone are valid or not without laboriously examining every score and every centimeter of every in situ specimen. Given the world-wide dispersal of fossils and occasional permission restrictions, DGS tracings just make things easier.

An earlier specimen of Sapeornis
(IVPP V13276; Fig. 4), from a previous post, is grossly similar and larger than STM 15-15. Subtle differences (e.g. toe length, coracoid shape, sternae presence, maxillary tooth presence, etc.) separate the two individuals, perhaps splitting them specifically. Even so, the two humeri are nearly identical in size and shape, despite the overall size differences.

Figure 4. Sapeornis specimen STM 15-15 reconstructed from DGS tracing, figure 1 compared to a more robust specimen with larger feet but an identical humerus.

Figure 4. Sapeornis specimen STM 15-15 reconstructed from DGS tracing, figure 1 compared to a more robust IVPP V13276 specimen with larger feet but an identical humerus.

Sapeornis chaoyangensis (Zhou and Zhang 2002. 2003; Early Cretaceous; IVPP V13276) is a basal ornithurine bird, the clade that gave rise to modern birds. Sapeornis nests in the same clade as Archaeopteryx recurva, the Eichstätt specimen, in the large reptile tree (LRT, 1729+ taxa). The short tail was tipped with a pygostyle and a fan of feathers. The coracoids were oddly wide and relatively short.


References
Serrano FJ, Pittman M, Kaye TG, Wang X, Zheng X and Chiappe LM 2020.
Laser-stimulated fluorescence refines flight modeling of the Early Crettaceous bird Sapeornis. Chapter 13 in Pittman M and Xu X eds. Pennaraptoran theropod dinosaurs. Past progress and new Frontiers. Bulletin of the American Museum of Natural History 440; 353pp. 58 figures, 46 tables.

What happened to the postfrontal and postorbital in birds?

Fauth and Rauhut 2020 bring us
“A short overview of the evolution of the skull of birds.”

From the first paragraph (Google translated from German)
“There are a number of advantages to being able to fly, be it the possibility of rapid geographical expansion, the settlement of trees, the escape from predators or the development of new feed sources, including prey capture. However, it cannot be regarded as the sole factor for the success of birds.”

Thereafter
the authors discuss and show (Fig. 1) skull traits, but make a traditional mistake based on a lack of attention to detail. Foth and Rauhut provide only one figure (Fig. 1), in which the postorbital is identified (in orange) only in Allosaurus (B) Archaeopteryx (C) and the enanthiornine, Shenqiornis (D). The postorbital is deemed absent in the extant Crax (A) and the extinct Ichthyornis (E) despite its presence in their diagram.

Figure 1. Theropod and bird skulls from Foth and Rauhut 2020. Postorbital is highlighted in orange, but not the same vestigial postorbital is not highlighted in bird skulls.

Figure 1. Theropod and bird skulls from Foth and Rauhut 2020. Postorbital is highlighted in orange, but not the same vestigial postorbital is not highlighted in bird skulls. Note: ‘Archaeopteryx’ is a wastebasket taxon with variation among the 13 known specimens.

Unfortunately
Foth and Rauhut took the easy way out by using previously provided oversimplified diagrams that lack the data needed to create a valid figure. They also followed paleontological tradition, which, at times like this, fail to provide valid data in the details.

Here are the missing details
in an actual Crax skull (Fig. 2) colorized using DGS methods. It shows a descending postfrontal (orange) and a vestigial postorbital (yelllow splint, but see caption for one more option). The postfrontal is largely fused to the frontal, but that does not negate its presence. No unfused frontal descends beyond mid depth in any vertebrate skull. We should label and score with reason, not with invalid traditions.

Figure 1. Crax tuberosa skull in three views.

Figure 2. Crax tuberosa skull in three views. Note the splint-like post0rbital (yellow). Alternate hypothesis: the splint is the postorbital process of the jugal (cyan, separate ossification from the base below the quadratojugal (olive). That would make the lumpy orange postfrontal the postfrontal + fused postorbital. Time to look at some embryos to see what is happening here: another great PhD dissertation.

The Eichstätt specimen of Archaeopteryx (= Jurapteryx)
shows the separation of the postfrontal (orange) from the frontal and the postorbital (in yellow) disarticulated and shifted slightly posteriorly in situ. This is the specimen basal to extant birds.

Figure 3. The Eichstätt specimen, Jurapteryx recurva, nests with the living ostrich, Struthio, presently in the LRT.

Figure 3. The Eichstätt specimen, Jurapteryx recurva, nests with the living ostrich, Struthio, presently in the LRT.

The tiny Early Cretaceous theropod, Scipionyx
(Fig. 4), demonstrates the separation of the frontal (blue), postfrontal (yellow-green) and postorbital (orange) in non-avian theropods. These elements tend to fuse with size. Phylogenetic miniaturization (= neotony) tends to separate the original elements. When dealing with shrinking taxa, like birds, try to keep this in mind.

Figure 1. Scipionyx skull and overall. The tail and feet are restored.

Figure 4. Scipionyx skull and overall. The tail and feet are restored.

The enantiornithine, Shenqiornis,
will be considered in greater detail In future blogposts.


References
Foth C and OWM Rauhut 2020. Eine kurze Betrachtung der Evolution des Vogelschädels [A short overview on the evolution of the skull of birds]. Jahresbericht 2019 und Mitteilungen 48. ISSN 0942-5845 ISBN 978-3-89937-253-3

More details on Parahesperornis

Bell and Chiappe 2020
provide additional insight and valuable photos of Parahesperornis alexi (Martin 1984; Fig. 1; Late Cretaceous ~90 mya) a smaller sister/ancestor to Hesperornis (Fig. 1) with more plesiomorphic traits.

Figure 1. Parahesperornis (from Bell and Chiappe 2020) compared to Hesperornis (Marsh 1890) to scale and not to scale. Here the glenoid to tail tip lengths are the same. Everything is exaggerated in Hesperornis.

Figure 1. Parahesperornis (from Bell and Chiappe 2020) compared to Hesperornis (Marsh 1890) to scale and not to scale. Everything is exaggerated in the derived taxon, Hesperornis.

Backstory
According to Bell and Chiappe, “The Hesperornithiformes constitute the first known avian lineage to secondarily lose flight in exchange for the evolution of a highly derived foot-propelled diving lifestyle, thus representing the first lineage of truly aquatic birds. First unearthed in the 19th century, and today known from numerous Late Cretaceous (Cenomanian-Maastrichtian) sites distributed across the northern hemisphere, these toothed birds have become icons of early avian evolution.”

Figure 2. Hesperornis cladogram from Bell and Chiappe 2020. Compare to LRT results in figure x.

Figure 2. Hesperornis cladogram from Bell and Chiappe 2020. Compare to LRT results in figure 3 where more taxa are tested and nested. Gansus should be closer to Hesperornis. Many taxa are omitted between Archaeopteryx and Asparavis here.

Figure 1. Click to enlarge. Toothed birds of the Cretaceous to scale.

Figure 3. Click to enlarge. Toothed birds of the Cretaceous to scale. Compare to figure 2. See the difference when more taxa are added.

Cladistics
Bell and Chiappe and the Large Reptile Tree (LRT, 1694+ taxa, illustrated in figure 3) are in broad agreement regarding the phylogenetic nesting of Parahesperornis (Fig. 2). Unfortunately, Bell and Chiappe don’t include enough taxa to understand the nesting of toothed birds within the clade of toothless birds, as recovered by the LRT (Fig. 3).

And what the heck 
are Gallus, the chicken, and Anas, the duck, doing in figure 2 nesting together? They are not related to one another in the LRT, but… (and here’s the key)… absent ANY pertinent transitional taxa, figure 2 is actually correct, a match with the LRT. Taxon exclusion delivers this oversimplified and misinforming cladogram (Fig. 2). More taxa, not more characters, makes a cladogram more and more accurate.


References
Bell A and Chiappe LM 2020. Anatomy of Parahesperornis: Evolutionary Mosaicism
in the Cretaceous Hesperornithiformes (Aves). Life 2020, 10, 62; doi:10.3390/life10050062
Marsh, OC 1880. Odontornithes, a Monograph on the Extinct Toothed Birds of North America. Government Printing Office, Washington DC.
Martin L 1984. A new Hesperornithid and the relationships of the Mesozoic birds. Transactions of the Kansas Academy of Science 87:141-150.

wiki/Hesperornis