When added to the large reptile (LRT, 2028 taxa), Middle Miocene Lycopsis (Figs. 1, 2; Cabrera 1927, Argot 2004) nest with Middle Eocene Vulpavus ovatus, the late surviving last common ancestor of the clade of terrestrial placental herbivores.
Figure 1. Lycopsis fossil with reconstructed skull.
Figure 2. Lycopsis skull. Colors added here. The jugal contacting the jaw glenoid is a traditional marsupial trait. Be sure to test all the traits over a wide gamut of taxa to make sure you don’t make a mistake with convergence.
What is a sprassodont? According to Wikipedia: “Sprassodonta is an extinct order of carnivorous metatherian mammals native to South America. They were first described by Florentino Ameghino 1894.
When tested in the LRT Lycopsis does not nest with metatheres (=marsupials), but within Placentalia.
“Here in the large sparassodonts’ molars were very similar to the sharp teeth of placental carnivores. Sparassodonts had a typical metatherian mode of dental replacement, replacing only the upper and lower third premolar throughout their lifetime.”
The LRT does not test molar replacement, which, like all traits, is prone to convergence.
“The early history of the Sparassodonta is poorly known, as most Paleocene and Eocene members of this group are only known from isolated teeth and fragmentary jaws. However, one species, the middle Eocene Callistoe vincei, is known from a nearly complete, articulated skeleton.”
In the LRT Callistoe nests with carnivorous marsupials, like Borhyaena, far from Lycopsis.
Figure 3. Vulpavus (Phlaodectes) ovatus (Matthew 1909; Middle Eocene; 12cm skull length) does not nest with Vulpavus palustris in the LRT. Instead it nests with Onychodectes from the Earliest Paleocene close to the origin of Condylartha and the large herbivorous placentals.
Unrelated, but given the same genus name, Vulpavus palustris is the last common ancestor of all placentals, large and small. Tree shrews are common at basal nodes for basal placentals like Carnivora, Volitantia, Glires and Primates.
Figure 4. Onychodectes is the first large terrestrial placental to appear after the Cretaceous.
Similar, yet different, Vulpavis ovatus (Fig. 3) is the last common ancestor of all terrestrial placentals, like Xenarthra and Condylarthra. There are no tree shrews in this clade and a long list of tree shrews in its ancestry. Again: Lycopsis nests with this clade and Vulpavis ovatus in the LRT.
This appears to be a novel hypothesis if interrelatioships. If not, please send a citation so I can promote it here.
References Argot C 2004. Functional-adaptive analysis of the postcranial skeleton of a Laventan Borhyaenoid, Lycopsis longirostris (Marsupialia, Mammalia). Journal of Vertebrate Paleontology 24(3):689–708. Cabrera A 1927. Datos para el conocimiento de los Dasiuroideos fósiles argentinos. Revista del Museo de La Plata 30:271–315.
Fortunguavis xiaotaizicus (Wang, O’Connor and Zhou 2014; Early Cretaceous; IVPP V18631; Figs. 1, 2) was described as a “robust enantiornithine bird with strongly recurved pedal unguals”. In the large reptile tree (LRT, 2026 taxa) Fortunguavis was also quite a bit larger than its immediate ancestor (Sulcavis) and descendants (Cratoavis + Iberomesornis, Figs. 1, 3).
Figure 1. Fortunguavis from Wang, O’Connor and Zhou 2014. Colors, digit diagrams and related taxa added here to the same scale. Note the recurved pedal unguals on all these taxa.
Here the crushed individual elements of the skull are traced and reconstructed for the first time.
This is the last time the postorbital connects to both the squamosal and the jugal in the extant bird lineage (Fig. 3)… except in parrots, like Ara, where the postorbital becomes circumorbital once again. And again by convergence in Aptornis where the postorbital reconnects to the squamosal.
Figure 2. Skull of Fortunguavis from Wang, O’Connoer and Zhou 2014, ventral view. Colors and reconstructions added here. Image at upper left by the authors fails to identify several individual bones.
With firsthand access to the fossil Wang, O’Connor and Zhou 2014 were unable, or decided not to identify the individual bones of the skull exposed in ventral view (Fig. 2 upper left). When the bones are traced using DGS methods (Fig. 2 color) those tracings can be used to create reconstructions and enter more scores to analysis (Fig. 2). I’ve been encouraging PhDs to adopt this method of tracing fossils with transparent colors since 2003. Other than those using µCT scans, few have done so in the last 18 years.
Figure 3. Relatives of Fortunguravis in phylogenetic order, plus Strutho, the ostrich. Arrows point to the postorbital-squamosal and postorbital jugal connections in Fortunguavis that are lost in later birds. Note the resemblance of Archaeovolans to its ancestor, Sulvavis, This appears to be a reversal, turning old genes on again.
The phylogenetic position of Fortunguavis in the LRT puts it at the very end of birds with a circumorbital bar and a postorbital-squamosal connection. Thereafter the slender and fading postorbital becomes a tiny vestige firmly attached to the postfrontal while the jugal no longer produces a postorbital process.
Fortunguavis is a relatively large and robust taxon. Immediate descendants, like Iberomesornis and Cratoavis, are much smaller, about the size of hummingbirds. This small size contributes to the absence of postorbital ossification just described. Essentially these two descendants were precocial adults, sexually mature at a younger age and smaller size. As in many clades, from Mammalia to Pterosauria, phylogenetic miniaturization introduces novel traits in reduced taxa. Thereafter descendants are free to grow to larger sizes while retaining their new traits, like Archaeovoloans and the London specimen of Archaeopteryx, both of which have only a vestige of a postorbital.
With the London specimen of Archaeopteryx in the lineage, that means Early Cretaceous Fortunguavis and Sulcavis were late survivors of an earlier Jurassic radiation. Given those millions of years prior to their appearances in Early Cretaceous strata, that is probably how Fortunguavis had time to become so large. Relative to its ancestor, Sulcavis, Fortunguavis retained juvenile traits: a shorter rostrum and larger eyes, despite its larger overall size (Fig. 2). Those juvenile traits were probably retained from phylogenetically miniaturized Jurassic ancestors.
Fortunguavis documents how Enantiornithes evolved to become Ornithurae. As noted earlier, after testing in the LRT, Enantiornithes is no longer a clade in the LRT. Enantiornithes is now a grade with basal members in the ancestry of all extant birds. There were four enanti-grade clades in the LRT appearing in step-wise progression preceding more modern toothed birds like Hesperornis and Ichthyornis.
As we’ve learned time after time we should never identify and categorize taxa by a small set of traits (= Pulling a Larry Martin“). Instead we should identify and categorize taxa only after testing them in a wide gamut cladogram, like the LRT. That way we can determine their last common ancestor. If that ancestor changes after more discoveries are made… well, welcome to the land of science.
References Wang M, O’Connor JK and Zhou Z 2014. A new robust enantiornithine bird from the Lower Cretaceous of China with scansorial adaptations. Journal of Vertebrate Paleontology 34(3):657-671.
Ever wonder what it was like for monitor lizards entering the water, taking their first step toward becoming giant mosasaurs (Fig. 1)? Enjoy this short video.
Click to view this short, narrated video of Australian water monitors swimming underwater.
Figure 1. Mosasaurus scale model.
Another lizard capable of swimming though apparently keeping its head above the water, is the basilisk, Basilicus (Fig. 2). You can see several short clips of its completely different swimming style here at the Wilson Lab.
Figure 2. Basiliscus, the “Jesus” lizard, runs underwater with its nose above the surface. Click the link above to the Wilson Lab.
Housekeeping to the large reptile tree (LRT, 2024+ taxa; subset Fig. 2) moved a few birds around in the last few days. More taxa and a critical review of earlier inductee scores recovered better matches (Fig. 1). Here (Fig. 2) are several novel insights into this trait-based phylogenetic analysis of birds and their extinct ancestors going back at least to the Late Jurassic.
Figure 1. Seems pretty obvious when you get Psophia and Chauna. together. Only the wing and feet sizes are distinctly different. Note the precursor spur on digit 1 of Psophia and the full spur on Chauna.
Psophia, the trumpeter, now nests with Chauna, the screamer. Note the tiny bump on the medial edge of manual digit 1 on Psophia evolves to become the otherwise unique, sharp, defensive spur on Chauna (Fig. 1).
Figure 2. Subset of the LRT focusing on birds. This is an update from prior iterations. Note the disparity among Solnhofen birds traditionally omitted but for one taxon, Archaeopteryx.
Rhynochetos, the kagu, a traditional flightless enigma taxon now nests with Megapodius, the scrubfowl. Both are from islands near Australia. Rhynochetos has been a long-running problem for the LRT, and other studies, hopefully finally resolved.
Figure 3. The kagu, Rhynochetos, now nests in the LRT with the scrubfowl, Megapodius.
Vultures now nest close to similarly large, flying bustards.
Flamingos and seriemas now nest basal to cuckoos and birds-of-paradise apart from secretary birds.
Mouse birds and tropic birds now nest with hornbills and toucans.
As before, nine Solnhofen birds are included. They still nest apart from one another (Fig. 2), documenting an earlier radiation than the Late Jurassic. Workers should include all nine, rather than just one traditional Archaeopteryx. The Solnhofen birds are not congeneric (Fig. 4).
The last common ancestor of all living birds, Archaeorhynchus, lived during the Early Cretaceous, documenting an earlier radiation of basal-most crown birds than the K-Pg boundary.
As before, this trait-based test (Fig. 2) does not recover a topology that matches genomic (gene-based) studies. The LRT documents a ladder-like or ivy-like branching in the bird clade, rather than a more bushy pattern with larger earlier diverging branches. Thus derived taxa need evolutionary time to appear and basal taxa probably had their genesis closer in time to Early CretaceousIteravis(Fig. 3) and Archaeorhynchus at the base of crown birds.
Figure 4. Taxa between Solnhofen birds and extant birds in the LRT. Click to enlarge. Here Iteravis nests as the last common ancestor of paleognath and neognath birds (= crown birds).
The bird subset of the LRT had its genesis a decade ago with the ostrich, Struthio, and the chicken, Gallus. Earlier errors were often multiplied until rectified in a continuing process that can only handle a few mismatched taxa at a time. In other words, I am learning something new every day, and these I share with you.
Why did it take so long to better understand bird phylogeny? Because modern bird phylogenies depend on gene-based scores, the trait-based LRT is plowing into unknown territories. Skull fusion in the beak and cranium led to earlier misunderstandings, clarified only after seeing hundreds of genera (Fig. 2). The work is never done. The LRT is not perfect, but better with every revision.
The ability to quickly view several skeletons and skulls with color segregated elements on twin monitors made this complex job much simpler. So did relying on the feedback from color-coded branches on the MacClade software tree. Perhaps now you can see now why trait-based bird studies were not done with such a wide gamut of extant and extinct taxa prior to the advent of the computer. Pen and ink outlines on crushed skeletons over a wide gamut of taxa are not as helpful in comparative anatomy. Here identifying every bit of every maxilla with transparent green in Photoshop has been more helpful than a traditional set of arrows and abbreviations. Here the ability to repair earlier misinterpretations proved to be essential, not only for the taxonomist in study mode, but also for transmitting data to readers when conclusions are presented.
This bird subset of the LRT appears to be a novel hypothesis of interrelationships. If not please provide prior citations so I can promote them here. Do not send gene studies.
Songzia heidangkouensis (LianHai 1990, Wang et al. 2012; Early Eocene) was considered a gruiform (Grus or crane relative). Here nests with another traditional gruiform, the nearly identical, but larger Crex, the corn crake.
Figure 1. Songzia was a tiny Eocene relative to the corn crake, Crex, in the LRT. Tracing originally from Wang et al. 2012, but moved around here.
Wang et al. 2012 reported, “Songziids were considered most closely related to Rallidae in the original description, but as yet no convincing evidence has been put forth concerning their affinities. Phylogenetic analyses based on twopreviously published data sets combining data from the new fossils did not provide conclusive evidence concerning the affinities of songziids.”
Figure 2. Images from Wang et al. 2012. Colors added here. Note the original authors did not see the same details traced here. Note the free posterior processes of the premaxilla, as in Crex.
The authors reported Songzia was ‘corncrake-sized’. Crex crex (Linneaus 1758, 11-45cm long) is the extant corncrake, a bird traditionally nesting closer to rails. Here in the LRT both Sonzia and Crex nest closer to crows derived from basal-most pigeons and coots.
Figure 3. The corn crake (Crex) now has an Eocene sister, Songzia. Crex flies similar to a game bird.
The birds within the LRT are getting a thorough housekeeping with every new taxon.
References LianHai H 1990. An Eocene bird from Songzi, Hubei province. Vertebrata PalAsiatica 28(1):34-42. Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata. Wang M, Mayr G, Zhang J and Zhou A 2012. Two New Skeletons of the Enigmatic, Rail-like Avian Taxon Songzia Hou, 1990 (Songziidae) from the Early Eocene of China. Alcheringa 36: 487-499.
Today’s newest birds are not related to each other in the large reptile tree (LRT, 2024 taxa, subset Fig. 5), but they are related to prior inductees.
Figure 1. An extant plover, Charadrius and an extinct plover, Scandiavis. The former is more gracil, the latter more robust with thicker limbs, a deeper pelvis and more robust tail. In Scandiavis missing pectoral bones are restored from Sturnus.
Scandiavis mikkelseni (Bertelli et al. 2013, Early Eocene; 17cm long) was described as a relative to Charadrius. It is a indeed a sister to Charadrius, the extant kildeer or ploverin the LRT (Fig. 5). Scandiavis has relatively shorter, more robust hind limbs, a deeper pelvis and more robust caudal series.
Given such proportions in Scandiavis, you might think it was more plesiomorphic, more primitive. However, when put into a phylogenetic context (Fig. 5), just the opposite is true. Ancestors had even longer legs. So Scandiavis was neotonous, retaining juvenile traits (e.g. shorter legs) into adulthood, convergent with all other short-legged birds descending from long-legged ancestors.
Figure 2. Scandiavis in situ from Bertelli et al. 2013 shown not quite life size.
The upturned premaxila of Scandiiavis is not found in related taxa. The sternum and wings are taphonomically missing in this otherwise well-preserved 3D specimen.
Figure 3. µCT scan of skull of Scandiavis from Bertelli et al. 2013. Colors added here.
Figure 4. Now the ibis, Threskiornis, has an ancestral taxon, the starling, Sturnus, that greatly resembles this prior oddity in the LRT. Here the shorter, smaller taxon is more primitive.
Sturnus vulgaris (Linneaus 1758, extant; Fig. 4) the extant common starling, also enters the LRT today. It is omnivorous, taking a wide range of invertebrates, as well as seeds and fruit. Note the down-turned beak, emphasized in the related ibis, Threskiornis (Fig. 4), and the related hoopoe, Upupa. That downturned beak had its origins in early Eocene Eofringillirostrum and the extant corn crake, Crex(Fig. 6), an omnivorous extant taxon that likely goes back to the Cretaceous. Another starling descendant is the crow, Corvus, and its descendants, the robins, jays, woodeckers and wrens.
Figure 5. Subset of the LRT focusing on crown birds. Every new taxon brings new insights into previously overlooked interrelationships.
Since the ibis, Threskiornis, first entered the LRT it has been something of an oddball, with that long curved bill distinct from other long-legged water birds. Then the hoopoe, Upapa, became a sister taxon. That became a new problem because the two do not share the same niche, have the same coloration nor are they similar in size. Only their skeletal traits revealed their kinship.
Today both the ibis and hoopoe are derived from the newly added starling. Unfortunately, the three do not share the same niche, have the same coloration, nor are they similar in size. Only their skeletal traits revealed their kinship. This clade of three is the definition of diverse.
Figure 6. The corn crake, Crex, is also an omnivore ancestral to starlings, ibis, grackles, crows and their more recent descendants in the LRT. This rather drab and camouflaged bird can be flushed from its grasslands habitat like a game bird, convergent with pheasants.
In college textbooks starlings are considered members of the Passeriformes. In the LRT (subset Fig. 5) starlings do not nest close to sparrows (genus Passer). In college textbooks ibis considered members of the Pelecanformes. In the LRT (subset Fig. 5) ibis do not nest close to pelicans (genus Pelecanus). So be careful when you read college textbooks. You may be required to give the wrong answer to pass their tests.
Adding characters, something paleo professors think is necessary to improve the LRT, would never reveal the starling + ibis relationship. Think about it. Only adding a starling can possibly link starlings to ibis. This bit of logic is something paleo professors keep failing to understand (given their history of taxon suppresion). That’s why taxon suppression continues to be the number one problem in paleontology. To counter that problem, the LRT minimizes taxon suppression by including so many more taxa (2024 at last count) and letting the software determine relationships. Many LRT taxa have never been tested together before. That’s why new interrelationships keep popping up. The LRT also demonstrates the dozens of times that genetic testing fails in deep time studies. So be careful when you read genomic (= genetic) studies. Also be careful if your professor asks you (and typically dozens of your fellow students) to create a genomic analysis in taxa that go back further than the Pliocene.
Phylogenetic analysis is something you learn by doing, not by reading from out-date university textbooks. Because this is science, anyone can figure out for themselves where textbooks and professors stray from supportable hypotheses to promote traditional myths. That may be why professor Darren Naish felt so threatened that he had to warn “The World” about the LRT almost a decade ago. Other professors have skirted around the issue of pterosaur origins, delicately or not so delicately avoiding actual pterosaur precursor taxa for twenty years in order maintain academic myths and a stream of revenue from students. Similar examples of taxon exclusion in paleontology go on and on.
You don’t need a degree to study paleontology. You do need a degree to teach paleontology in a university setting. That’s their system, where you have to pay to play. Dr. Naish paid for several years to get his PhD, then complained when I played without paying. Naish could have offered encouragement. After all, sometimes outsiders (= independent scientists) shed new light when they move into territories that have never been studied before. In the last ten years no one else has put 2000+taxa in a single online cladogram. Instead Darren Naish and others responded with unprofessional, immature and inappropriate name-calling. Dr. Naish could have decided to create his own competing analysis or encouraged a grad student under his direction to do so. He’s had nearly a decade. Apparently Naish and others would rather complain, dismiss, ignore and ridicule than compete. Then “if you do get published, you will not be cited”, said another professor, S. Christopher Bennett, who is likewise not happy when independent scientists make discoveries that were supposed to have been reserved for them alone.
Here’s to all the independent scientists out there… Happy Holidays!
The nesting of starlings with ibis appears to be a novel hypothesis of interrelationships. If not, please provide a citation so I can promote it here.
References Bertelli S, Lindow BEK, Dyke GJ and Mayr G 2013. Another charadriiform-like bird from the lower Eocene of Denmark. Paleontological Journal. 47(11): 1282–1301. Linnaeus C von 1758. Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus 1. Editio decima, reformata. Holmiae [Stockholm], Laurentii Salvii.
Glyptolepis paucidens (Agassiz 1844; Middle Devonian; 20cm; Figs. 1, 2) was a smallish rhipidistian, a lobefin fish with primitive lobes. Traditionally considered a porolepiform, after testing Glyptolepis does not nest with the porolepiform, Porolepis (Fig. 3), which nests several nodes apart in the LRT, closer to coelocanths.
Figure 1. Glyptolepis skull.
Figure 2. Two specimens of Middle Devonian Glyptolepis in situ
According to Wikipedia, “Porolepiformes … were thought to have given rise to the salamanders and caecilians independently of the other tetrapods. Recent phylogenetic reconstruction places porolepiformes close to lungfishes. More recent evidence has shown that at least one genus Laccognathus was most likely amphibious.”
Figure 3. Porolepis and Holoptychius skulls compared. These porolepiformes are not related to Glyptolepis in the LRT, but developed similar sizes and shapes by convergence.
Here in the large reptile tree (LRT, 2021 taxa) Glyptolepis nests closer to the tetrapodomorph, Cabonnichthys (Fig. 4), far from Porolepis and Holoptychius (Fig. 3), despite several convergent traits. The porolepiform, Laccognathus (Fig. 5), has a flatter, wider skull similar to that of Glyptolepis by convergence. Moving Glyptolepis to Porolepis or vice versa adds 30 steps to the LRT.
Figure 4. The tetrapodomorph, Cabonnicthys from Ahlberg and Johanson 1997, colors added here. Compare to figures 1 and 2. Note the palatal fangs, larger than the marginal teeth and the straight tail with symmetrical caudal fins. Importantly, the pre-sacral length is elongate. The caudal length is short. The lobe-fins are small.
Porolepis posnaniensis (Kade 1858, named by Woodward 1891; Early Devonian) was a large, slow-moving lobefin with small eyes, related to Holoptychius, not Glyptolepis, contra academic traditions.
Ahlberg 1991 re-examined Porolepiformes at the start of the software era of cladistics. Ahlberg reported, “A cladistic analysis based on 54 characters places the Porolepiformes as sister-group of a clade Powichthys + Youngolepis + Diabolepis + Dipnoi. The porolepiform-lungfish clade is the sister group of another clade containing tetrapods, panderichthyids, osteolepiforms and rhizodonts.”
The LRT employs more taxa. The LRT widely separates porolepiforms from lungfish, which are the sister clade to tetrapodomorphs llike panderichthys, osteolepiforms and rhizodonts. The LRT nests Youngolepis closer to Porolepis than to lungfish (= Dipnoi). These relationships await confirmation with a similar taxon list.
Figure 5. Laccognathus diagram from Downs et al. 2011. Colors and tetrapod homolog labels added here.
This appears to be a novel hypothesis of interrelationships. If not, please provide a citation so I can promote it here. This discovery was accomplished by simply adding taxa, letting the software decide interrelationships and not assuming that similar traits indicate relationships rather than convergence. We’ve seen this before with ‘turtle’ origins, ‘whale’ origins, pterosaur origins and more.
References Ahlberg PE 1991. A re-examination of sarcopterygian interrelationships, with special reference to Porolepiformes. Zoological Journal of the Linnean Society 103(3):241–287, Ahlberg PE and Johanson Z 1997. Second tristichopterid (Sarcopterygii, Osteolepidformes) from the Upper Devonian of Canowindra, New South Wales, Australia, and phylogeny of the Tristichopteridae. Journal of Vertebrate Paleontology 17(4):653–673. Cloutier R and Ahlberg PE 1996. Morphology, Characters, and the Interrelationships of Basal Sarcopterygians. In Melanie LJ Stiassny; LR Parenti and GD Johnson (eds.). Interrelationships of Fishes. p. 457. Kade G 1858. Ueber die devonischen Fischreste cines diluvial Blockes. Meseritz. pp.17-18. Woodward AS 1891. Catalogue of the Fossil Fishes in the British Museum (Natural History). Part II. Catalogue of the Fossil Fishes in the British Museum (Natural History) 2.
Iteravis huchzermeyeri (Zhou, O’Connor and Wang 2014 Ju et al. 2021; Early Cretaceous; IVPP V18958, Figs. 1, 2) nests between Hongshanornis and crown birds as their new last common ancestor in the large reptile tree (LRT, 2021 taxa; graphic Fig. 3).
Figure 1. Iteravis in situ.
Ju et al. 2021 found no differences between Iteravis and Gansus. This is probabaly due to taxon exclusion as neither Megapodius nor Nahmavis(Figs. 3, 4), two basal crown birds in the LRT, are mentioned in the text.
Figure 2. Iteravis skull in situ and reconstructed.
Figure 3. Gansus skull in situ and reconstructed. Compare to Iteravis skull in figure 2. Similar, but not the same.
Zhou, O’Connor and Wang 2014 nested Gansus and Iteravis close to one another due to taxon exclusion. Here the two are distinct and derived from Hongshanornis. Traditional workers keep trying to include unrelated geese and chickens at the base of crown birds, where they don’t belong.
Figure 4. Nahmavis fossil (FMNH PA778) overall. Images from Musser and Clarke 2020.
Descendants of Early Cretaceous Iteravis evolved to become both paleognath (e.g. Megapodius) and neognath (e.g. Nahmavis, Fig. 4) birds.
Nahmavis is a late survivor of that Early Cretaceous radiation of crown birds known from the famous Messel Formation of the Early Eocene. It was originally considered close to the origin of gruiformes and charadriformes (Musser and Clarke 2020). Here it nests with the Kori bustard, Ardeotis, one of the largest extant flying birds in Africa at 1.3m long.
Figure 5. Taxa between Solnhofen birds and extant birds in the LRT. Click to enlarge. Here Iteravis nests as the last common ancestor of paleognath and neognath birds (= crown birds).
References Hou L and Liu Z 1984. A new fossil bird from Lower Cretaceous of Gansu and early evolution of birds. Sci. Sin. Ser. B. 27:1296−1302. Huang J, Wang X, Hu Y, Liu J, Peteya JA and Clarke JA 2016. A new ornithurine from the Early Cretaceous of China sheds light on the evolution of early ecological and cranial diversity in birds. PeerJ, 4: e1765. doi:10.7717/peerj.1765 Ju S-B, Wang X-R, Liu Y-C and Wang Y 2021. A reassessment of Iteravis huchzermeyeri and Gansus zheni from the Jehol Biota in western Liaoning, China. China Geology 4(2):197–204. Li Y et al. (5 co-authors) 2011. New material of Gansus and a discussion on its habit. Vertebrata PalAsiatica 49:435–445. Liu et al. (6 co-authors) 2014. An advanced, new long-legged bird from the Early Cretaceous of the Jehol Group (northeastern China): Insights into the temporal divergence of modern birds. Zootaxa 3884(3):253–266. You et al. (12 co-authors) 2006. A nearly modern amphibious bird from the Early Cretaceous of Northwestern China. Science 312:1640–1643. Zhou S, O’Connor JK and Wang M 2014. A new species from an ornithuromorph (Aves: Ornithothoraces) dominated locality of the Jehol Biota. Chinese Science Bulletin 59(36):5366–5378,
After review and rescoring with a larger selection of toothed birds, the Late Cretaceous loon-mimic, Hesperornis (Fig. 1), now nests with the STM9-52 specimen (mistakenly referred to Yanornis, Fig. 1). And these nest with the London specimen of Archaeopteryx (FIg. 1). And these nest in the LRT with the infamous Archaeovolans (originally Archaeoraptor, a composite fossil).
So, based on phylogenetic bracketing, in the large reptile tree (LRT, 2021 taxa) incomplete and infamous Archaeovolans should have had a long slender stiff tail (Fig. 1).
Figure 1. Taxa between Solnhofen birds and extant birds in the LRT. Click to enlarge. Here Archaeovolans nests basal to the London specimen of Archaeopteryx and Hesperornis. Other Solnhofen bird specimens (at top) nest closer to one another. This is why it is so important to test all the Solnhofen birds in analyses, something that is never done outside of the LRT.
According to Wikipedia “Zhou et al. found that the head and upper body actually belong to a specimen of the primitive fossil bird Yanornis. A 2002 study found that the tail belongs to a small winged dromaeosaur, Microraptor, named in 2000. The legs and feet belong to an as yet unknown animal.”
Figure 2. Archaeoraptor from Rowe et al. 2000. Colored areas indicate different sources for matrix and fossils there in. The feet belong to Yanornis or a close relative. Click here for more backstory.
According to the LRT the upper body nests two nodes apart from Yanornis(Fig. 1).
That makes me wonder if the Chinese farmers who found Archaeovolans noticed that that it had a long tail, but not well preserved. So they added a tail and hind limbs from another available specimen. The nesting of Archaeovolans basal to birds with a long tail and apart from Yanornis is an interesting twist to this story of the farmers’ crude understanding of phylogenetic bracketing.
Another notable difference in today’s revised LRT:: Enantiornithes is no longer a discreet clade, but a transitional grade between Solnhofen birds and crown birds. Prior to housekeeping enantiornine birds did form a separate clade with the London specimen of Archaeopteryx (Fig. 1) at the base.
Yet another notable difference in today’s revised LRT: Phylogenetically miniaturized taxa (e.g. Microcursor and Protopteryx) nest between large Solnhofen birds and later Early Cretaceous birds.
Archaeovolans repatriatus (IVPP V12444, Czerkas and Xu 2002) This Early Cretaceous bird had a controversial beginning as Archaeoraptor liaoningensis). Originally the the long stiff tail and hind limbs came from a different specimen, but phylogenetic bracketing indicates this genus did have a long stiff tail (Fig. 1) Zhou and Zhang (2002) considered the specimen another Yanornis, a taxon with a short pygostyle. Here Archaeovolans nests between enantiornithes and the London specimen of Archaeopteryx leading to Hesperornis (Fig. 1) and on the other branch, Eogranivora + higher birds.
Archaeopteryx lithographica The London specimen – BMNH 37001, is the holoytype for the genus and species. Here it nests between Archaeovolans (above) and the STM9-52 specimen previously assigned to Yanornis (Fig. 1).
“Needs a new name” taxon (Zhang & Zhou, 2001, STM9-52, Aptian, Early Cretaceous) was originally considered an ornithurine bird, close to Yanornis. Here this toothed bird with oversized hands, a long neck, and small head nests basal to a toothed bird with no hands: Hesperornis (Fig. 1). The sternum was greatly enlarged laterally and posteriorly, without a keel, as an anchor for powerful flight or swimming muscles, as in penguins. Tiny gastralia here are about to disappear. The sacrum is wide and the elements are not fused. The pubis extends the body posteriorly. Tiny triangular patellas are present, precursors to large patellas on Hesperornis.
Hesperornis regalis (Marsh 1872a, b c) Late Cretaceous ~90 mya, 1.8m in length, was a toothed, flightless, marine loon-mimic with asymmetrical feet. It swam with powerful hind limb tipped by elongate lateral toes (digit #4), seen to a lesser extend in precursor clade members. This is one more example of flightlessness in the largest of its kind together with reduced wings. The premaxilla was elongated. The pectoral girdle was reduced and the humerus was a vestige. Note the large patella (in blue) extending above the femur. Huge muscles were anchored to the long pelvis. The teeth had bulbous roots and were set in a groove, convergent with mosasaurs like Tylosaurus.
Hesperornis, with no hands, is a sister to the STM9-52 specimen. with the largest hands among tested taxa. At first glance, that might seem weird, but think of it this way. While Hesperornis swam like a loon, the STM9-52 specimen might have swam like a penguin, by flapping those large hands. Apparently (Fig. 1) this big hand / no hand split had origins prior to the Late Jurassic (based on the London specimen of Archaeopteryx).
As reported earlier, key to understanding the previously murky origins of hesperornithids is the inclusion of precursor taxa that traditionally did not enter prior analyses. Taxon exclusion continues to be the number one problem in paleontology today. This is just one more example.
This appears to be a novel hypothesis of interrelationships. If not, please send a citation to I can promote it here.
References Czerkas SA and Xu 2002. Feathered Dinosaurs and the Origin of Flight, Czerkas SJ ed., The Dinosaur Museum Journal 1: vi + 136 pp. Marsh OC 1872a. Discovery of a remarkable fossil bird. American Journal of Science, Series 3, 3(13): 56-57. Marsh OC 1872b. Preliminary description of Hesperornis regalis, with notices of four other new species of Cretaceous birds. American Journal of Science 3(17):360-365. Marsh OC 1872c. Notice of a new and remarkable fossil bird. American Journal of Science, Series 3, 4(22): 344. 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. von Meyer H 1861. Archaeopteryx litographica (Vogel-Feder) und Pterodactylus von Solenhofen. Neues Jahrbuch für Mineralogie, Geognosie, Geologie und Petrefakten-Kunde. 1861: 678–679. Owen R 1863. On the Archaeopteryx von Meyer, with a description of the fossil remains of a long-tailed species from the lithographic stone of Solnhofen. Philosophical Transactions of the Royal Society, London 153: 33-47. Zhang F and Zhou Z 2001. A Primitive Enantiornithine Bird and the Origin of Feathers. Science 290 (5498): 1955-1959.
The first several specimens attributed to the bird genus Gansus yumenensis (Hou and Liu 1984, You et al. 2006; Early Cretaceous; Fig. 1) were not complete and none included the skull, mandibles or anterior neck. Here in the large reptile tree (LRT, 2021 taxa) the best data was taken from a freehand drawing.
Figure 1. Three reconstructions of Gansus based on two specimens of G. zheni and a chimaera of five specimens referred in 2006 to G. yumenensis. The latter has a longer pedal digit 4.
By happy contrast Gansus zheni(Liu et al. 2014 BMNHC–Ph 1342; Early Cretaceous; Fig. 1) is known from a complete skeleton. Now it nests between smaller Hongshanornis and similarIteravis (Fig. 2) in the LRT. These are not aquatic taxa, but likely shoreline taxa.
Figure 2. Taxa between Solnhofen birds and extant birds in the LRT. Click to enlarge. Other than the flightless, marine loon-mimic, Hesperornis, most Cretaceous birds were constrained to the small size of Gansus.
What was Gansus like, according to the experts? From Wikipedia,“You et al. (2006) concluded that the anatomical characteristics of Gansus were similar to foot-propelled diving birds, such as Hesperornis (from the Cretaceous) and the loons (Gaviidae) and grebes (Podicipedidae).On the other hand, Li et al. (2011) concluded that Gansus showed a more similar morphology to ducks.Two years later, Nudds et al. (2013) showed that the pectoral limb length proportions of Gansus were most similar to swifts and hummingbirds (Apodiformes), while the pelvic limb length proportions fell within the modern birds (Neornithes), showing similarities with grebes (Podicipedidae), albatross (Diomedeidae) and cormorants (Phalacrocoracidae), suggesting that Gansus was both volant and capable of diving to some degree using either foot-propelled or, perhaps, both its wings and its feet for underwater locomotion.”
Figure 3. Gansus full size on a 72 dpi computer monitor. It was larger than a dipper (genus: Cinclus) the smallest bird that ‘flies’ underwater – if Gansus swam at al.
Sharp-eyed readers will note a revision of this portion of the LRT (Fig. 2) that moves a few taxa around. We will look at those in more detail soon. The ancestry of Hesperornis seems particularly novel.
References Hou L and Liu Z 1984. A new fossil bird from Lower Cretaceous of Gansu and early evolution of birds. Sci. Sin. Ser. B. 27:1296−1302. You et al. (12 co-authors) 2006. A nearly modern amphibious bird from the Early Cretaceous of Northwestern China. Science 312:1640–1643. Liu et al. (6 co-authors) 2014. An advanced, new long-legged bird from the Early Cretaceous of the Jehol Group (northeastern China): Insights into the temporal divergence of modern birds. Zootaxa 3884(3):253–266.
The Pterosaur Heresies 