Dorsetisaurus: a Mesozoic tegu, not an anguimorph

Known from the Early Cretaceous of Mongolia
and the Late Jurassic of Portugal, Dorsetisaurus purbeckensis (BMNH R.8129, skull width: 1.4cm; Hoffstetter 1967; Fig. 1) was attributed to the clade of glass lizards (Anguimorpha) originally and in two later papers. Evans 2006 nested it between the highly derived legless skink, Amphisbaenia, and the basal gecko (in the LRT), Chometokadmon (which Evans considered an anguimorph).

FIgure 1. Dorsetisaurus bits and pieces restored here and scored nests in the LRT with Tupinambis, the extant tegu.

FIgure 1. Dorsetisaurus bits and pieces restored here and scored nests in the LRT with Tupinambis, the extant tegu.

By contrast
in the large reptile tree (LRT, 1318 taxa) Dorsetisaurus nests with the basal scerloglossan, lacertoid, teiid, Tupinambis (Fig. 2), the extant tegu lizard. Even the slight notch in the ventral maxilla is retained over 120 million years of evolution.

Figure 2. Tupinambis is the extant tegu lizard, a sister to Dorseitsaurus in the LRT.

Figure 2. Tupinambis is the extant tegu lizard, a sister to Dorseitsaurus in the LRT.

On a side note:

Gauthier et al. 2012 put together two squamate trees of life, one based on traits, another based on genes. Neither matches the LRT, which includes more fossil taxa.

References
Evans SE, Raia P, Barbera C 2006. The Lower Cretaceous lizard genus Chometokadmon from Italy. Cretaceous Research 27:673-683.
Gauthier, JA, et al. 2012. Assembling the squamate tree of life: Perspectives from the phenotype and the fossil record. Bulletin of the Peabody Museum of Natural History 53.1 (2012): 3-308.
Hoffstetter  R 1967.
Coup d’oeil sur les Sauriens (lacertiliens) des couches de Purbeck (Jurassique supérieur d’Angleterre Résumé d’un Mémoire). Colloques Internationaux du Centre National de la Recherche Scientifique 163:349-371.

wiki/Dorsetisaurus
http://fossilworks.org/bridge.pl?a=taxonInfo&taxon_no=38022

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A reexamination of Milosaurus: Brocklehurst and Fröbisch 2018

I just found out that not one but two Aerosaurus specimens were tested and are to be found in the SuppData for this paper. So, what happened here? I’ll dig deeper to look for a solution. 

Solution: The cladistic analysis in the Brocklehurst and Fröbisch 2018 Milosaurus study recovered nearly 2000 most parsimonious trees for 60 taxa. So the phylogeny is not well resolved. By contrast the LRT is well resolved. Relatively few of the characters could be scored for Milosaurus in the Brocklehurst and Fröbisch study. None overlapped with Ianthodon, the purported closest relative. By contrast the LRT found a suite of traits that were shared by Milosaurus and Aerosaurus to the exclusion of all other tested taxa. 

Brocklehurst and Fröbisch 2018 reexamine
“a large, pelycosaurian-grade synapsid” not from the Early Permian, but from the Latest Carboniferous of Illinois Milosaurus (Fig. 1) was first described by DeMar 1970 as a member of the Varanopsidae (= Varanopidae). Brocklehurst and Fröbisch note, “Milosaurus itself has received little attention since its original description. The only attempt to update its taxonomic status was by Spindler et al. (2018). These authors included Milosaurus in a phylogenetic analysis that, although principally focused on varanopids, contained a small sample of pelycosaurs from other families. Milosaurus was found nested within Ophiacodontidae, as the sister to Varanosaurus.”

Ultimately
Brocklehurst and Fröbisch nested Milosaurus with Haptodus within the Eupelycosauria.

Figure 1. The pes of Milosaurus in situ, reconstructed and compared to Aerosaurus, its sister in the LRT.

Figure 1. The pes of Milosaurus (FMNH PR 701) in situ, reconstructed and compared to Aerosaurus, its smaller sister in the LRT. PILs added to restore distal phalanges.

By contrast
the large reptile tree nested Milosaurus with Aerosaurus (Fig. 1; Romer 1937, A. wellesi Langston and Reisz 1981), a taxon not listed by Brocklehurst and Fröbisch. Based on the pes alone, Milosaurus was twice the size of Aerosaurus. Aerosaurus is a basal synapsid more primitive than Haptodus and the Pelycosauria. Aerosaurus and Milosaurus nest between Elliotsmithia + Apsisaurus and Varanops.

Unfortunately
Brocklehurst and Fröbisch included the unrelated clade Caseasauria in their study of Synapsida, and did not include Aerosaurus. They also include Pyozia, not realizing it is a proto-diapsid derived from and distinct from varanopid synapsids. So, once again, taxon exclusion and inappropriate taxon inclusion are the reasons for this phylogenetic misfit.

Distinct from Haptodus, and similar to Aerosaurus
in Milosaurus metatarsals 2 and 3 align with p1.1, not mt1. The base of mt 5 is quite broad. Other traits also attract Milosaurus to Aerosaurus, including an unfused pubis + ilium. I was surprised that so few traits nested Milosaurus in the LRT as it continues to lump and split taxa with the current flawed list of multi-stage characters.

References
Brocklehurst N and Fröbisch J 2018. A reexamination of Milosaurus mccordi, and the evolution of large body size in Carboniferous synapsids. Journal of Vertebrate
Paleontology, DOI: 10.1080/02724634.2018.1508026
DeMar R. 1970. A primitive pelycosaur from the Pennsylvanian of Illinois. Journal of Paleontology 44:154–163.
Langston W Jr and Reisz RR 1981. Aerosaurus wellesi, new species, a varanopseid mammal-like reptile (Synapsida: Pelycosauria) from the Lower Permian of New Mexico. Journal of Vertebrate Paleontology 1:73–96.
Romer AS 1937. New genera and species of pelycosaurian reptiles. Proceedings of the New England Zoological Club 16:90-96.

wiki/Aerosaurus

Llanocetus: not a ‘baleen whale with teeth and gums’

Hailed in the popular press
(see below) as a ‘baleen whale with teeth and gums’, Llanocetus denticrenatus (Mitchell 1989; Fordyce and Marx 2018; 8m in estimated length; 34 mya), nests in the large reptile tree (LRT, 1320 taxa) with archaeocete (toothed) whales, not with mysticetes (baleen whales).

Fordyce and Marx described Llanocetus
from a virtually complete skull (Fig. 1) as “the second oldest mysticete known.” Their phylogenetic analysis nested Llanocetus with Mystacodon, which they describe as “the oldest mysticete,” but earlier the LRT nested it with archaeocete toothed whales, too.

Figure 1. Llanocetus, hailed as a baleen whale with teeth and gums, is just a large archaeocete.

Figure 1. Llanocetus, hailed as a baleen whale with teeth and gums, is just a large archaeocete.

According to Fordyce and Marx, “The broad rostrum has widely spaced teeth marked with dental abrasion and attrition, suggesting biting and occlusal shearing.” Such traits are unexpected in a filter-feeder.

Figure 1. (above) Zygorhiza kochi from George Mason University website, likely captured from Kellogg 1936.

Figure 2. (above) Zygorhiza kochi from George Mason University website, likely captured from Kellogg 1936. To make the jaws fit and teeth occlude the mandible had to be reduced and the cranium had to tilted down posteriorly.

Fordyce and Marx attempt to force-fit their new taxon into the Mysticeti
when they report, “As in extant mysticetes, the palate bears many sulci, commonly interpreted as osteological correlates of baleen. Unexpectedly, these sulci converge on the upper alveoli, suggesting a peri-dental blood supply to well-developed gums, rather than to inter-alveolar racks of baleen. We interpret Llanocetus as a raptorial or suction feeder, revealing that whales evolved gigantism well before the emergence of filter feeding.”

No mention of desmostylians here…

Figure 1. Rorqual evolution from desmostylians, Neoparadoxia, the RBCM specimen of Behemotops, Miocaperea, Eschrichtius and Cetotherium, not to scale.

Figure 3. Rorqual evolution from desmostylians, Neoparadoxia, the RBCM specimen of Behemotops, Miocaperea, Eschrichtius and Cetotherium, not to scale. It is worthwhile noting the similarities shown between Cetotherium and Ilanocetus. Such convergences are the source of Fordyce and Marx’s hypotheses.

Fordyce and Marx conclude in their abstract,
“This scenario differs strikingly from that proposed for odontocetes, whose defining adaptation-echolocation-was present even in their earliest representatives.” 

Unfortunately,
the authorse have no idea that those ‘earliest representatives’ of odontocetes are represented today by tenrecs that also echo-locate and travel in pods, as we learned earlier here.

Once again,
taxon exclusion is to blame for the earlier mistakes. Fordyce and Marx refuse to test desmostylians in their analyses, similar to pterosaur workers who refuse to test tritosaur lepidosaurs, and turtle workers who refuse to test small horned pareiasaurs. That’s why the wide gamut taxon list of the LRT comes in so handy. You don’t have to guess or force-fit any taxa… just let the software and the taxon list do your work for you.

No wonder whale workers are not letting
my papers on whale, turtle and pterosaur origins be published. 

References
Fordyce RE and Marx FG 2018. Gigantism precedes filter feeding in baleen whale evolution. Current Biology 28(10):1670–1676.

wiki/Llanocetus

https://www.techtimes.com/articles/227549/20180512/34-million-year-old-skull-from-antarctica-reveals-baleen-whales-had-teeth-and-gums.htm

False positives in an LRT subset lacking fossil taxa

I think you’ll find this phylogenetic experiment both
gut-wrenching and extremely illuminating. While reading this, keep in mind the importance of having/recovering the correct outgroup for every clade and every node. That can only be ascertained by including a wide gamut of taxa—including fossils. Adding taxa brings you closer and closer to echoing actual events in deep time while minimizing the negative effects of not including relevant/pertinent taxa.

Today you’ll see
what excluding fossil taxa (Fig. 1) will do to an established nearly fully resolved cladogram, the large reptile tree (LRT, 1318 taxa). Earlier we’ve subdivided the LRT before, when there were fewer taxa in total. Here we delete all fossil taxa (except Gephyrostegus, a basal amniote used to anchor the cladogram because PAUP designates the first taxon the outgroup).

PAUP recovers 250+ trees
on 264 (~20%) undeleted extant taxa.

  1. Overall lepidosaurs, turtles, birds and mammals nest within their respective clades.
  2. Overall lepidosaurs nest with archosaurs and turtles with mammals, contra the LRT, which splits turtles + lepidosaurs and mammals + archosaurs as a basal amniote dichotomy.
  3. Overall mammals are not the first clade to split from the others, contra traditional studies. All pre-mammal amniotes in the LRT are extinct.
  4. Within lepidosaurs, the highly derived horned lizards and chameleons are basal taxa, contra the LRT, which nests Iguana as a basal squamate.
  5. Within lepidosaurs, geckos no longer nest with snakes, contra the LRT.
  6. Crocodiles nest with kiwis, as in the LRT, but it is still amazing that PAUP recovered this over such a large phylogenetic distance.
  7. Within aves, so few taxa are fossils in the LRT that the tree topology is very close to the original.
  8. Within mammals marsupials no longer nest between monotremes and placentals
  9. …and because of this carnivores split off next.
  10. Contra the LRT, hippos are derived from the cat and dog clade, all derived from weasels.
  11. Within mammals odontocetes no longer nest with tenrecs.
  12. Within mammals mysticetes nest with odontocetes, no longer nest with hippos.
  13. Contra the LRT, whales are derived from manatees and elephants.
Figure 1. Subset of the LRT focusing on Amniota (=Reptilia) with all fossil taxa deleted. Gephyrostegus, a Westphalian fossil is included as the outgroup.

Figure 1. Subset of the LRT focusing on Amniota (=Reptilia) with all fossil taxa deleted. Gephyrostegus, a Westphalian fossil is included as the outgroup.

BTW,
here are the results based on using the basal fish, Cheirolepis, as an outgroup:

    1. The caecilian, Dermophis, nests as the basalmost tetrapod.
    2. Followed by the frog and salamander.
    3. Squamates branch off next with legless lizards and burrowing snakes at a basalmost node. Terrestrial snakes are derived from burrowing snakes. Gekkos split next followed by varanids and skinks. Another clade begins with the tegu and Lacerta, followed by iguanids. Sphenodon nests between the horned lizards, Moloch and Phyrnosoma + the chameleon.
    4. Turtles split off next with the soft-shell turtle, Trionyx, at the base.
    5. One clade of mammals split off next with echidnas first, then elephant shrews and tenrecs, followed by a clade including the pangolin, seals and other basal carnivores. Cats and dogs split off next followed by hippos, then artiodactyls, perissodactyls, the hyrax, elephants, manatees, mysticetes and odontocetes.
    6. Another clade of mammals include edentates, followed by tree shrews and glires, followed by (colugos + bats) + primates, followed by another clade of basal carnivores, followed by marsupials.
    7. The final clade is Crocodylus + extant birds, which are not well resolved and split apart into two major clades with some subclades maintaining their topology while other clades split apart. So the archosaurs nest together.

This test emphasizes the need for the inclusion of fossil taxa in order to recover a gradual accumulation of traits at all nodes, which takes us closer to actual evolutionary patterns in deep time.

The roadrunner (Geococcyx) has a funky, wide pelvis

You can’t tell
by looking at the skeleton in lateral view (Fig. 1), but the roadrunner pelvis (Figs. 1–3) is definitely different in dorsal and ventral view.

Figure 2. Geococcyx the roadrunner skeleton. Pelvis in several views.

Figure 1. Geococcyx the roadrunner skeleton. Pelvis in several views.

On a recent trip to the Sam Noble Museum
(Oklahoma Museum of Natural History, OMNH) in Norman, Oklahoma, I happened to look down at a roadrunner skeleton (genus: Geococcyx, Figs. 1–3) in the kid’s section. That pelvis struck me as quite odd and indeed it is, relative to other birds, other theropods and other dinosaurs. Even the road-running ostrich (genus: Struthio, Fig. 4) does not have such a wide pelvis.

Figure 1. Roadrunner (genus: Geococcyx) in dorsal view from the Sam Noble Museum in Norman OK USA.

Figure 2. Roadrunner (genus: Geococcyx) in dorsal view from the Sam Noble Museum in Norman OK USA. Image flipped left to right.

Roadrunners are ground cuckoos,
better at sprinting than flying. The heavily muscled hind limbs of roadrunners are well anchored on this laterally expanded pelvis. Truth be told: I have not, but would like to see a muscle comparison between a roadrunner and ostrich (Fig. 4)… then try to figure out why the roadrunner pelvis is so different.

Figure 2. Closeup of figure 1. with sacrum yellow and ilium green. This is a strange pelvis for a theropod or bird.

Figure 3. Closeup of figure 1. with sacrum yellow and ilium green. This is a strange pelvis for a theropod or bird.

Geococcyx californum (Lesson 1829, Wagler 1831; up to 60cm long) the extant roadrunner is a small terrestrial cuckoo/trumpeter and a basal neognath with a posteriorly rotated pedal digit 4, unrelated to parrots and toucans with a similar toe. Geococcyx nests with the cuckoo, Coccyzus and both nest with the long-legged trumpeter, Psophia.

Figure 1. Acetabulum of Struthio.

Figure 4. Acetabulum of Struthio, the ostrich, more typical of birds, theropods and dinosaurs in general.

Galliformes
(chickens, turkeys, peacocks, curassaws, also have a posterior wide pelvis. These are also active terrestrial birds.

References
Lesson RP 1828, 1829. Genera des Oiseaux u Nort de l’Amérique, et Synopsis des especes qui vivent aux Etats-Unis; par Charles-Lucien Bonaparte. Féruss. Bull. 2 sect 13:122-125.
Wagler 1831. Einige Mitheilungen über Thiere Mexicos. Oken’s Isis 24:510–535.
Zinoviev A 2007. Apparatus of bipedal locomotion of cuculiforms (Aves, Cuculiformes): Scenario of an adaptive radiation. Zoologichesky Zhurnal 86(10):1–9.

wiki/Geococcyx

A new extremely tiny pre-snake: Barlochersaurus

Just out,
Daza et al.. 2018 describe a privately-owned, Mid-Cretaceous, teeny-tiny, ‘enigmatic’ lizard preserved in amber, Barlochersaurus winhtini (Figs. 1, 3; 1.5 in total length). The authors report, “The fossil is one of the smallest and most complete Cretaceous lizards ever found, preserving both the articulated skeleton and remains of the muscular system and other soft tissues. Despite its completeness, its state of preservation obscures important diagnostic features.We determined its taxonomic allocation using two approaches: we used previously identified autapomorphies of squamates that were observable in the fossil; and we included the fossil in a large squamate morphological data set.”FIgure 1. From Daza et al. 2018 and color overlays applied here. FIgure 1. From Daza et al. 2018 and color overlays applied here.

FIgure 1. From Daza et al. 2018 and color overlays applied here.Phylogenetically the authors report,
“Results from the phylogenetic analysis places the fossil in one of four positions: as sister taxon of either Shinisaurus crocodilurus or Parasaniwa wyomingensis, at the root of Varanoidea, or in a polytomy with Varanoidea and a fossorial group retrieved in a previous assessment of squamate relationships.”

Figure 2. Subset of the LRT showing stem snakes, snakes and their sister group, the geckos.

Figure 2. Subset of the LRT showing stem snakes, snakes and their sister group, the geckos.

Unfortunately this lack of resolution is due to taxon exclusion.
In the large reptile tree (LRT, 1318 taxa; subset Fig. 2) Barlochersaurus nests between the stem snakes Pontosaurus (Fig. 5) and tiny Tetrapodophis (Figs. 3, 4) neither of which is listed in the text of the Daza et al. paper.

Figure 3. Tetrapodophis and Barlochersaurus at full scale when seen on a monitor at 72 dpi.

Figure 3. Tetrapodophis and Barlochersaurus at full scale when seen on a monitor at 72 dpi.

According to Wikipedia
“Anguimorpha include the anguids (alligator lizardsglass lizardsgalliwasps and legless lizards)They are characterized by being heavily armored with non-overlapping scales, and almost all having well-developed ventrolateral folds (excluding Anguis). Anguidae members can, however, be somewhat difficult to identify in their family, as members can be limbed or limbless, and can be both viviparous and oviparous.” The LRT tests several anguids. They do not attract Barlochersaurus as well as Tetrapodophis and Pontosaurus.

Figure 4. The skull of Tetrapodophis, the proximal outgroup taxon to living snakes.

Figure 4. The skull of Tetrapodophis, the proximal outgroup taxon to living snakes.

Pontosaurus
(Fig. 5) has a longer tail and is much larger overall. The manus and pes of Pontosaurus are similar in proportion and detail to those of Barlochersaurus.

Figure 2. Pontosaurus and its parts. Data from Caldwell 2006. This is one of the last taxa we know in the snake lineage that still had a pectoral girdle.

Figure 2. Pontosaurus and its parts. Data from Caldwell 2006. This is one of the last taxa we know in the snake lineage that still had a pectoral girdle.

The Daza team printed 3D replicas,
blown up to 10 times the original size. These are publicly available at Florida’s Museum of Natural History and Harvard’s Museum of Comparative Zoology.

Earlier
we looked at a more primitive pre-snake with legs (JKZ-Bu267) also found in amber here.

And, oh, yeah… did I forget to mention?
Phylogenetic miniaturization at the genesis of major and minor clades in the LRT strikes again! This time, to the extreme!

References
Daza JD, Bauer AM, Stanley EL, Bolet A, Dickson B and Losos JB 2018. A enigmatic miniaturized and attenuate whole lizard from the Mid-Cretaceous amber of Myanmar. Breviora 563: 18pp.

https://www.pbs.org/wgbh/nova/article/paperclip-lizard/

Misinterpreting Zhongornis

A few years ago
O’Connor and Sullivan 2014 took another look at a small bird-like theropod, Zhongornis, originally identified as a bird. They thought they saw “striking resemblances to both Oviraptorosauria and Scansoriopterygidae.” According to Wikipedia, “The authors reinterpreted Zhongornis as the sister taxon of scansoriopterygids, and further suggested that this clade (Zhongornis + Scansoriopterygidae) is the sister group of Oviraptorosauria.”

The original paper by Gao, et al. 2008
(O’Connor was a co-author) considered Zhongornis a bird, “the sister group to all pygostylia,” which is an invalid clade in the LRT. Several disparate clades developed pygostyles in the LRT.

Figure 4. Confuciusornithiformes to scale. Note the lack of a pygostyle in the majority of taxa.

Figure 4. Confuciusornithiformes to scale. Note the lack of a pygostyle in the majority of taxa.

By adding more relevant taxa,
in the large reptile tree (LRT, 1315 taxa) Zhongornis nested between Archaeopteryx (= Wellnhoferia) grandis and Confusciusornis (Fig. 1). Scansoriopterygids, in the LRT, are descendants of the Solnhofen bird, ‘Archaeopteryx‘ #12.

Figure 2. Zhongornis in situ.

Figure 2. Zhongornis in situ, skull reconstructiion, pes, manus and tail.

Zhongornis haoae (Gao et al. 2008; D2455; Early Cretaceous). Lack of fusion and bone texture indicate the Zhongornis holotype is a juvenile. The femoral heads and necks are not visible, perhaps not yet ossified. Even so, the wing feathers are well-develped, so the specimen is not a hatchling, but close to fledging, according to Gao et al.

Figure 3. Zhongornis pectorals as traced here and as traced by O'Connor and Sullivan (right).

Figure 3. Zhongornis pectorals as traced here and as traced by O’Connor and Sullivan (right).

The problem with the O’Connor and Sullivan paper was…
taxon exclusion. They did not test all Solnhofen birds, but considered them all Archaeopteryx and selected one to test. They did not realize that various Solnhofen birds are basal to ALL later bird clades, even those that gave up flying and grew to large to fly.

Figure 4. Zhongornis pelvic and tail area as traced here and as traced by O'Connor and Sullivan.

Figure 4. Zhongornis pelvic and tail area as traced here and as traced by O’Connor and Sullivan. The red bones are pubes. The green ones are ilia or impressions thereof.

We talk about elongate coracoids
when we talk about birds (Aves).

O’Connor and Sullivan 2014 report, “The coracoid is not well-preserved and is largely overlapped by other elements, making it difficult to confirm the original description (Gao et al., 2008) of this bone as strut-like; in DNHM D2456 it appears short, robust, and trapezoidal, a primitive morphology that characterizes oviraptorosaurs and scansoriopterygids, as well as dromaeosaurids, troodontids, Archaeopteryx and sapeornithiforms.”

In contrast
Zhongornis clearly has two elongate, barbell-shaped coracoids (Fig. 3), as in Confuciusornis.

In ReptileEvolution.com the coracoids of scansoriopterygids and Archaeopteryx have elongate coracoids. By contrast, Sapeornis and other sapeornithiforms have relatively short coracoids, reduced along with the forelimbs as the body size increased. This is sometimes called a reversal. Short coracoids can also be found in extant flightless birds.

Don’t judge or nest a taxon on just a few or a few dozen traits.
Always let the unbiased software place the taxon. To put limits on your taxon list.

References
Gao C-L, Chiappe LM, Meng Q-J, O’Connor JK, Wang X, Cheng X-D and Liu J-Y 2008. A new basal lineage of early Cretaceous birds from China and its implications on the evolution of the avian tail. Palaeontology 51(4):775-791.
O’Connor J-M and Sulivan C 2014.
Reinterpretation of the Early Cretaceous maniraptoran (Dinosauria: Theropoda) Zhongornis haoae as a scansoriopterygid-like non-avian, and morphological resemblances between scansoriopterygids and basal oviraptorosaurs. Vertebrata PalAsiatica 52(1)1–9.

wiki/Changchengornis
wiki/Confuciusornis
wiki/Zhongornis