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 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 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 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 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.

Stylaria, Opabinia and Tullimonstrom side-by-side

Yesterday we took a detour into the realm of invertebrates
comparing large, extant, colorful, free-swimming marine flatworms and trilobites to the giant of the Cambrian, Anomalocaris. Although the three taxa show a gradual accumulation of traits and are overall similar in shape, readers suggested some ‘further reading’ of the academic literature was needed.

That reading has been fascinating
and a defense of that minor thesis is forthcoming. So far that argument looks like it will need several building blocks.

Figure 1. Opabinia in situ, enlarged several times.

Meanwhile… today brings one of those building blocks.
Opabinia (Figs. 1, 2) is yet another strange Cambrian taxon often found in the same cladogram as Anomalocaris (Figs. 3, 4). Whittington’s (1975) first interpretation of Opabinia was met with laughter due to the implausible ‘strangeness’ of the fossil.

Perhaps the following
will take some of the strangeness out of Opabinia. It has some overlooked relatives, one still living, Stylaria, a tiny segmented worm with a mobile proboscis (Fig. 2). Note the presence of eyes, a head section, a tail section and precursors to swimming lobes present as needle-like lateral spines, one per segment. Opabinia only stands out as odd (Fig. 3)  until you add a few similar taxa.

Figure 2. Comparing the extant worm, Stylaria to Cambrian Opabinia and Carboniferous Tullimontrom. All three share a similar morphology that has not been fully explored yet. The proboscis does not aid in feeding Stylaria and it probably acted as a simple probe and/or holdfast for Opabinia and Tullimonstrom. Note the lack of legs in any of these taxa.

According to Wikipedia,
“When the first thorough examination of Opabinia in 1975 revealed its unusual features, it was thought to be unrelated to any known phylum, although possibly related to a hypothetical ancestor of arthropods and of annelid worms. However other finds, most notably Anomalocaris, suggested that it belonged to a group of animals that were closely related to the ancestors of arthropods and of which the living animals onychophorans (velvet worms) and tardigrades may also be members.”

Given the many shared traits with Stylaria, the proboscis in Opabinia does not appear to be used elephant-like, as Whittington 1975 suggested, for carrying prey items back to the ventral mouth. Rather the proboscis was more likely used as a sand probe and/or a poison delivery system. Feeding would have taken place in a more typical flatworm fashion, by settling over a docile prey item and everting soft ventral mouth parts to haul in food that had stopped struggling.

Smith and Ortega-Hernández 2014
offered a competing hypothesis of interrelationships (Fig. 3). In their study focusing on the terminal claws of another Burgess Shale former enigma, Hallucigenia, the authors included Anomalocaris and two related anomalocarids. Opabinia was the outgroup. Stylaria and Tullimonstrum were excluded taxa.

I have no issues with the presence of walking velvet worms nesting with walking tardigrades and walking Hallucigenia. However, I think legless, swimming Opabinia and Anomalocaris do not belong here. An omitted primitive legless taxon, Stylaria (Fig. 2) needs to be added to the Smith and Ortega-Hernandez taxon list to ascertain or modify relationships. More outgroups are probably needed. Or delete the inappropriate swimmers.

Figure 3. Illustrated cladogram from Smith and Ortega-Hernández 2014 (colors, arrows, gray taxa added here) inserts flat, swimming anomalocardids in a claodogram that otherwise features cylindrical lobe-footed crawling worms as basal taxa. Note how Opabinia stands out as the oddball here. 

Cong et al. 2014 offer a second competing hypothesis
based on their study of Lyrarapax (Fig. 3), a tiny genus clearly related to Anomalocaris. In the Cong et al. cladogram (Fig. 4) Opabinia nests a few nodes further away from several specimens attributed to Anomalocaris. Stylaria and Tullimonstrum were once again omitted from the Cong et al. taxon list.

Figure 4. Cladogram from Cong et al. 2014 nest Anomalocaris in the clade Radiodonta derived from nematodes and penis worm in which the mouth and anus are both terminal.

The case is building that 
Anomalocaris and Opabinia never went through an evolutionary phase in which the body was cylindrical with the short clawed feet of velvet worms and tardigrades. Instead these two appear to have evolved directly from free-swimming segmented worms without legs. Let’s keep adding taxa to figure this out.

---

References
Bergström J 1986. Opabinia and Anomalocaris, unique Cambrian arthropods. Lethaia. 19 (3): 241–246.
Whittington HB 1975. The enigmatic animal Opabinia regalis, Middle Cambrian Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society B. 271 (910): 1–43 271.

wiki/Opabinia

 

Anomalocaris: how flatworms transition to trilobites

According to Wikipedia,
“Anomalocaris (“unlike other shrimp”, or “abnormal shrimp”) is an extinct genus of radiodont (anomalocaridid), an order of animals thought to be closely related to ancestral arthropods.”

That is confirmed below (Fig. 1). But where did Anomalocaris come from?

According to Wikipedia,
“Stephen Jay Gould cites Anomalocaris as one of the fossilized extinct species he believed to be evidence of a much more diverse set of phyla that existed in the Cambrian Period, discussed in his book Wonderful Life, a conclusion disputed by other paleontologists.”

That is not confirmed below. Based on phylogenetic bracketing, Anomalocaris evolved from flatworms and into trilobites. Thus, these do not increase the diversity of phyla in the Cambrian, but blend one into another.

Figure 1. Possible evolution of Anomalocaris after phylogenetic bracketing between flatworms and trilobites.

Where else do we find such a mouth?
That’s the first clue to the origin of anomalocarids.

Figure x. Added April 7. As predicted Kiisortoqia bridges the gap between Anomalocaris and Triarthrus, the trilobite.

Evidently overlooked until now,
certain flatworms have a similar concentric ventral mouth (Fig. 1).

Anomalocarids apparently had the fluidity of motion
of a large swimming flatworm (see video below), combined with the segmentation of trilobites (= arthropod ancestors).

Distinct from flatworms, but like trilobites,
an anus appears posteriorly.

Like tentacled flatworms and trilobites with antennae,
two armored tentacles appear on anomalocarids,

Unlike flatworms, but like trilobites,
a pair of lateral eyes on short stalks appear.

A YouTube video
featuring Burgess Shale expert Professor Des Collins explains how the bits and pieces of Anomalocaris came together historically over several years as he holds a model of a large specimen.https://www.youtube.com/watch?v=xNbaHOJ7GGk

According to the Des Collins website:
“The fossil Anomalacaris was unlike any living animal and was misidentified over a period of 100 years revealing the false starts that can happen in scientific research. Collins set out to piece together the entire animal by looking at the vast trove of Burgess Shale fossils at the Royal Museum of Ontario where he worked. He discovered more pieces of the puzzle and realized that previous fossils that were described as separate organisms were, in fact, part of the animal Anomalacaris. Once he had assembled the entire animal, he had a model built to show what a fearsome predator it must have been.”

Or not. Anomalocaris was large, but its mouth was not ideally suited to crack open and attack the hard-shelled animals that were evolving in the Cambrian. According to the Wired.com article cited below, “We found that it’s extremely unlikely Anomalocaris could eat most trilobites,” said James Whitey Hagadorn, the research team’s leader and a paleontologist at the Denver Museum of Nature and Science. “It couldn’t close its mouth all of the way, its mouth was too soft to crush trilobite shells.”

Anomalocaris arising from large free-swimming flatworms
appears to be a novel hypothesis of interrelationships. If not, please provide a citation so I can promote it here.

This just in (March 11, 2021):
Tests show Anomalocaris was not a trilobite eater, but preferred mush, like modern flatworms do.
https://phys.org/news/2010-11-ancient-shrimp-monster-fierce.html
https://phys.org/news/2010-11-earth-great-predator-wasnt.html

---

References
Daley AC, Paterson JR, Edgecombe GD, García-Bellido DC and Jago JB 2013. Donoghue P (ed.). New anatomical information on Anomalocaris from the Cambrian Emu Bay Shale of South Australia and a reassessment of its inferred predatory habits. Palaeontology: n/a. doi:10.1111/pala.12029
Whiteaves JF 1892. Description of a new genus and species of phyllocarid Crustacea from the Middle Cambrian of Mount Stephen, BC. The Canadian Record of Science. 5 (4).
Whittington HB and Briggs DE 1985. The largest Cambrian animal, Anomalocaris, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society B. 309 (1141): 569–609.

wiki/Anomalocaris
shapeoflife.org/video/des-collins-paleontologist-burgess-shale
wired.com/2010/11/anomalocaris-trilobite-bite/

Mao et al. 2020 “Pull a Larry Martin” with the multituberculate, Sinobaatar

Mao et al. 2020 report on a
crushed and articulated Early Cretaceous multituberculate specimen of Sinobaatar (Fig. 1). Presently several species are known. This one was µCT scanned.

From the abstract
“We report a new Cretaceous multituberculate mammal with 3D auditory bones preserved. Along with other fossil and extant mammals, the unequivocal auditory bones display features potentially representing ancestral phenotypes of the mammalian middle ear.”

The authors made several basic mistakes with Sinobaatar.

1. By concentrating on one set of traits (the middle ear), rather than the entire skeleton, the authors ‘Pulled a Larry Mrartin“.
2. By not including derived members of Glires (gnawing placentals) in their phylogenetic analysis, their cladogram (Fig. 2) suffers from taxon exclusion and inappropriate taxon inclusion (e.g. Liaoconodon and Origolestes are mammal-mimics living in the Early Cretaceous alongside real mammals).
3. The authors did not consider the possibility of convergence brought about by a reversal. When members of Glires are added to analysis (Fig. 3), the reversal becomes obvious (Fig. 4).

The takeaway:
Not matter what the configuration of the middle ear in Sinobaatar, if the rest of the skeleton nests it in Glires, maximum parsimony says: Sinobaatar and all multituberculates nest in Glires.

Figure 1. Sinobaatar skull in two views. DGS colors added. The skull was crushed from side to side.

The authors report in the SuppData:
“Given several recent efforts of higher-level phylogenies of mammaliaforms [1-3] and the relatively stable position of multituberculates (Sinobaatar in particular) within mammals in all these studies, we consider it redundant to run another phylogenetic analysis.”

Redundant, yes, if using the same taxon list. But adding members of Glires to that taxon list changes everything.

Figure 2. Cladogram from Mao et al. 2020 with the wrong phylogenetic order, repaired on frame 2 in which Origolestes and Liaoconodon are late-surviving mammal mimics, not mammals.

The wide gamut of the taxon list
in the large reptile tree (LRT, 1729+ taxa; subset Fig. 3) minimizes taxon exclusion. When taxa that have never been tested together before get tested together, sometimes they nest together. You just have to let the software do what it does best and keep shoveling in more taxa.

Figure 3. Subset of the LRT focusing on basal placentals, including multituberculates.

The authors report,
“While the auditory bones already detached from the dentary in the three phenotypes, the transitional middle ear of Liaoconodon is most primitive in that the malleus and ectotympanic have long anterior processes that are still in contact with the ossified Meckel’s cartilage; thus, hearing and chewing functions were not completely separated. Origolestes is more derived in having lost the bony contact of the auditory bones to the ossified Meckel’s cartilage so that hearing and chewing functions were decoupled.” 

Without a valid cladogram the authors assume the order of evolution without really knowing. In the LRT Origolestes is not a mammal and the more primitive of the two, hinting at an earlier stage in a reversal. The LRT lumps and separates taxa to reveal such reversals.

Figure 4. Comparing multituberculate origins: Cziki-Sava et al. vs. LRT.

The authors report, 
“With the assumption that the DMME evolved independently in monotremes, therians, and multituberculates, there should be no common ancestral phenotype of the middle ear for these clades.”

That is incorrect. The LRT nests multituberculates within the gnawing clade, Glires (Fig. 3). The LRT indicates the primitive nature of the middle ear of multituberculates is a reversal likely caused by the great propalinal movement of the gnawing jaw interfering with and preventing normal maturation of the placental middle ear and leaving it at a more primitive state. You can have more confidence in this hypothesis because more taxa are tested, ‘leaving no stone unturned.’

Every description you’ll ever see
of multituberculates, plesiadapiformes, carpolestids and the aye-aye, Daubentonia, includes the phrase, “rodent-like” for a very good reason. That’s because they are closely related, something Mao et al. 2020 and other multituberculate experts do not yet realize. Adding taxa always resolves problems. Just do it. Don’t “Pull a Larry Martin.”

---

References
Mao F-G, Liu C, Chase MH, Smith AK, Meng J 2020. Exploring ancestral phenotypes and evolutionary development of the mammalian middle ear based on Early Cretaceous Jehol mammals. Research Article Earth Sciences. National Science Review, nwaa188, https://doi.org/10.1093/nsr/nwaa188

wiki/Multituberculata
wiki/Sinobaatar

Space-time and the imaginary ‘tesseract’

A little off-topic today
Astronomer, lecturer, author, and voice of science, Carl Sagan
introduced many of us oldsters to the tesseract, a four-dimensional analogue of the cube. YouTube provides a video of that segment from ‘Cosmos; A Personal Voyage’, a PBS television series from 1980. Here (see below) Sagan holds the 3D ‘shadow’ of a hypothetical 4D tesseract. Click to play.

Other producers have provided more recent videos
explaining their visions of the fourth dimension and the tesseract using digital animation (see below).

These presentations are barking up the wrong tree.
The fourth dimension is much simpler and very real. We live it every day.

As everyone already knows,
time is the fourth dimension. Space-time provides both the third dimension and the fourth dimension, otherwise known as ‘reality’.

‘Now’ and ‘then’ is all there is to the fourth dimension. Nothing more.
Any 3D shape in the now moment has already moved at right angles from the then moment ever since the Big Bang — when space-time began. How far apart those moments are… or how far apart those shapes are… or in what direction those shapes have moved… are historical givens. Alternatively these parameters up to you, if you are planning something that changes from moment to moment, as any engineer, animator or puppeteer can tell you.

Shadows on 2D walls and tesseracts
are just fanciful illusions in space-time, over-thinking while overlooking the obvious and very real point. When you see a graph or chart that has an X, Y and Z axis and wonder how the next axis lies at right angles to these three, just flip the page and show a new X, Y and Z axis chart that charts another moment in time. You are not stuck with just one page representing just one moment. Later, you can animate those pages by projecting them at 24 or 30 frames per second, when you have enough ‘moments’ to make your point.

There’s nothing more to the fourth dimension
than ‘now‘ and ‘then‘, except to say, it’s a one way street and there’s no leap-frogging in time or space.

The tesseract turns out to be a model
of all the possible futures of a 3D object in space-time. That 3D object can go in any direction and end up anywhere in space for a second measurement for every new ‘now‘ moment. As it always turns out, all possible futures are reduced to one real ‘now‘ moment, ready for the next ‘now‘ moment to come along while looking back on a long line of ‘then‘ moments.

No need to complicate things
any further. Somehow this easy solution has been traditionally overlooked. This may be a novel hypothesis. If not, please provide the citation so I can promote it as a precedent.

Marsupial cladograms: Tooth traits recover false positives

A traditional dependence on molar traits
has obscured and mixed up fossil mammal relationships (Fig. 1) when compared to phenomic studies using skulls and skeletons of extant taxa and fossils (Fig. 2). In this way, tooth traits are shown to be like gene traits. They deliver false positives that are not validated by taxa tested by a large suite of traits from nose to tail.

Luo et al. 2011
published their cladogram nesting Juramia as the basalmost placental recovered from a cladogram of mammal interrelations based largely on tooth traits (Fig. 1).

Figure 1. From Luo et al. 2011, mammal claodgram focused on Juramaia employing many tooth traits. Compare to the LRT in figure 2 which minimizes tooth traits.

In stark contrast,
the large reptile tree (LRT, 1728+ taxa) nested Juramaia as a monotreme (Prototheria).

Figure 2. Subset of the LRT cladogram of basal Mammalia. Note the traditional clade Metatheria is a grade with new names proposed here.

Figure 3. Juramaia (Late Jurassic, 160 mya) is more completely known and nests with monotremes not placentals.

 

References
Luo Z-X, Yuan C-X, Men Q-J and JiQ 2011. A Jurassic eutherian mammal and divergence of marsupials and placentals. Nature 476: 442–445. doi:10.1038/nature10291.

Asiatherium enters the LRT: mammal nomenclature issues follow

Everyone agrees
that Asiatherium (Figs, 1,2) nests close to Monodelphis, Caluromys and placentals. Trofimov and Szalay 1994 agreed. So did Denyer, Regnault and Hutchinson 2020. So did the large reptile tree (LRT, 1729+ taxa, subset Fig. 3).

Figure 1. Asiatherium in situ from Szalay and Trofimov 1996.

Asiatherium reshetovi (Trofimov and Szalay 1994, Szalay and Trofimov 1996; PIN 3907; Late Cretaceous; 80mya; Figs. 1, 2) is a key Mongolian metathere ancestral to monodelphids and Caluromys, which is ancestral to placentals. It is derived from Triassic sisters to extant late survivors, Didelphis, Gilronia and Marmosops.

Figure 2. Asiatherium skull slightly modified (longer lateral view premaxilla to match dorsal and ventral views) from Szalay and Trofimov 1996. Colors added here.

The problem is,
according to results recovered by the LRT, mammal clade nomenclature needs to go back to basics. Several modern mammalian clade names are found to be junior synonyms of traditional clades in the LRT.

Prototheria (Gill 1872) is a junior synonym
for Monotremata (Bonaparte 1837) in the LRT.

According to Wikipedia, “Prototheria is a paraphyletic subclass to which the orders Monotremata, Morganucodonta, Docodonta, Triconodonta and Multituberculata have been assigned, although the validity of the subclass has been questioned.”

In the LRT Morganucodon is a a marsupial (see below). Docodon is a taxon within Monotremata. Triconodon is a taxon within Monotremata. Multituberculata is a clade within the placental clade Glires (Fig. 4). So, the clade Monotremata is monophyletic and has precedence.

Theria (Parker and Haswell 1897) is a junior synonym
of Marsupialia (Illiger 1811). Metatatheria (Thomas Henry Huxley 1880) is also a junior synonym of Marsupialia.

The late-surviving basalmost marsupial in the LRT (Fig. 4), Ukhaatherium (Fig. 3), has epipubic (marsupial) bones. That long rostrum indicates this taxon is close to monotremes.

Figure 3. Ukhaatherium in situ.

Unlike the monophyletic clade Monotremata,
a series of nested marsupial clades are present. The last of these gives rise to Placentalia, only one of several that lose the pouch (Fig. 4). New names are proposed here where appropriate:

1. Marsupialia = Ukhaatherium and kin + all descendants (including placentals)
2. Paleometatheria = Morganucodon and kin + all descendants.
3. Didelphimetatheria = Eomaia and kin + all descendants
4. Phytometatheria = Marmosops and kin + all descendants
5. Carnimetatheria = Asiatherium and kin + all descendants
6. Transmetatheria = Caluromys and kin + all descendants
7. Placentalia = Vulpavus and kin + all descendants

Figure 4. Subset of the LRT cladogram of basal Mammalia. Note the new names proposed here.

Basal marsupial taxa are omnivores. 
Derived phytometatheres are herbivores. Derived carnimetatheres are carnivores to hyper-carnivores. Transmetatheres (Carluromys) and basal Placentalia remain omnivores.

In the LRT Eutheria (Gill 1872) is a junior synonym
of Placentalia (Owen 1837). Omnivorous civets like Nandinia are basal placentals. Carnivora is a basal placental clade following basal placental civets.

Competing cladograms
Denyer, Regnault and Hutchinson 2020 recently looked at the marsupial patella, or more specifically the widespread absence or reduction of the kneecap. The authors concluded, “metatherians independently ossified their patellae at least three times in their evolution.”

Unfortunately, Denyer et al. tested Caenolestes, the ‘shrew opossum’. Not surprisingly it nested close to placentals in their cladogram. Caenolestes was earlier nested in the LRT within the placental clade, Glires, closer to shrews than to opossums. It has no pouch, but converges with marsupials in several aspects. Inappropriate taxon inclusion, like Caenolestes, occurs due to taxon exclusion. Excluded taxa would have attracted and removed the inappropriate taxon. Taxon exclusion plagues Denyer et al.

Historically, you may remember,
Bi et al. 2018, while presenting Early Cretaceous Ambolestes, suffered from massive taxon exclusion and traditional bias in attempting to produce a cladogram of mammals. Bi et al. recovered Sinodelphys (Early Cretaceous) and Juramaia (Late Jurassic) as ‘eutherians’. In the LRT both are monotremes.

Other basal mammal cladograms
depend too much on tooth traits. Convergence in tooth traits creates problems, as documented earlier. We’ll look at this problem in more detail soon.

The above subset of the LRT appears to be a novel hypothesis
of interrelationships. If not, please provide a citation so I can promote it.

---

References
Bi S, Zheng X, Wang X, Cignetti NE, Yang S, Wible JR. 2018. An Early Cretaceous eutherian and the placental marsupial dichotomy. Nature 558(7710):390395 DOI 10.1038/s41586-018-0210-3.
Denyer AL, Regnault S and Hutchinson JR 2020. Evolution of the patella and patelloid in marsupial mammals. PeerJ 8:e9760 http://doi.org/10.7717/peerj.9760
Szalay FS and Trofimov BA 1996. The Mongolian Late Cretaceous Asiatherium, and the early phylogeny and paleogeography of Metatheria. Journal of Vertebrate Paleontology 16(3):474–509.
Trofimov BA and Szalay FS 1994. New Cretaceous marsupial from Mongolia and the early radiation of Metatheria. Proceedings of the National Academy of Sciences 91:12569-12573

New paper on Eldeceeon, one of our earliest reptile ancestors

Ruta, Clack and Smithson 2020
bring us new two new specimens of the amphibian-like reptile, Eldeceeon (pronounced ‘L-D-C-on’, Smithson 1994; Viséan, 335mya), adding to the two previously described specimens (Fig. 1). These two are the basalmost taxa in the Archosauromorpha in the large reptile tree (LRT, 1725+ taxa, subset Figs. 4, 5). The authors confirm a relationship to Silvanerpeton (Fig. 2), the last common ancestor of all reptiles in the LRT. They share a deep pelvis for large egg laying and a large lumbar region  for egg-carrying in females. This trait is shared with males unless all specimens around this node found so far are all females.

Figure 1. The two earlier specimens attributed to Eldeceeon that nest together at the base of the Archosauromorpha. Note the extended lumbar region and deep pelvis ideal for laying large eggs on both specimens.

Unfortunately, 
the authors consider these taxa “either as the most plesiomorphic stem amniote clade or as a clade immediately crownward of anthracosauroids.” 

They didn’t test enough taxa to nest Elcedeceeon and Silvanerpeton as basal amniotes (= reptiles), nor did they test enough taxa to recover a basal dichotomy in the Viséan at the base of the Reptilia. One branch, the Archosauromorpha, gives rise to synapsids and non-lepidosaur diapsids. At its base, Eldeceeon is an amphibian-like reptile that laid (by phylogenetic bracketing) amniotic eggs.

From the abstract:
“A detailed account of individual skull bones and a revision of key axial and appendicular features are provided, alongside the first complete reconstructions of the skull and lower jaw and a revised reconstruction of the postcranial skeleton.”

Actually those first complete reconstructions were done here in 2014. Worse yet, the authors created by freehand one chimaera reconstruction (their figure 7e), not appreciating the distinctions between the two previously known specimens (Fig. 1).

From the abstract
“The late Viséan anthracosauroid Eldeceeon rolfei from the East Kirkton Limestone of Scotland is re-described. Information from two originally described and two newly identified specimens broadens our knowledge of this tetrapod. 

Figure 2. Four cladograms from Ruta, Clack and Smithson 2020 seeking a nesting place for included taxa. Compare to Figure 4, a subset of the LRT. They need more outgroup taxa to solve their self-confessed phylogenetic problems.

From the Discussion
“The most vexing aspect of the Eldeceeon postcranium is the configuration of its rib cage, with long and curved ribs confined to the anterior half of its trunk. We hypothesise that the space between the most posterior trunk ribs and the pelvis was occupied by an unusually large puboischiofemoralis internus 2 (PIFI2).”

All basal amniotes have this sort of lumbar region. Gravid lizards use this space to carry eggs (Fig. 3). Ruta, Clack and Smithson overlook this possibility because their cladograms (Fig. 2) do not nest Eldeceeon and kin among the reptiles.

Figure 3. Extant lizards, A. gravid, B. in the process of laying eggs, C. with egg clutch.

In the LRT Anthracosaurus
(Fig. 4) nests far from Eldeceeon (Fig. 5), Silvanerpeton, Gephyrostegus and other stem reptiles (= Reptilomorpha). Anthracosaurus nests in the same basal tetrapod clade as Ichthyostega and Proterogyrinus in the LRT. So taxon exclusion has mixed up the order of taxa in the cladogram of Ruta, Clack and Smithson 2020. More taxa solve such phylogenetic problems.

Other taxa are also adversely affected by taxon exclusion.
Ruta, Clack and Smithson report, “Eucritta melanolimnetes Clack, 1998 shares characters with groups as diverse as baphetids, temnospondyls, and anthracosaurs (Clack 2001); perhaps unsurprisingly, this combination of features has resulted in alternative phylogenetic placements for this taxon, either as a derived stem tetrapod or as a basal crown tetrapod shifting between alternate positions on either side of the lissamphibian–amniote dichotomy”. In the LRT (subset Fig. 2) Eucritta is a sister to Tulerpeton, the proximal outgroup clade to the Amniota + Gephyrostegus, which may be an amniote, too. It is the proximal outgroup to the Amniota in the LRT and includes all of the basal amniote traits.

Figure 4. Subset of the LRT focusing on basal tetrapods. Colors indicate number of fingers known. Many taxa do not preserve manual digits. Eldeceeon arises after Silvanerpeton. Compare to cladograms in figure 2.

Eldeceeon rolfei (Smithson 1994) ~27 cm in total length, Early Carboniferous ~335 mya, is from the same formation that yielded Silvanerpeton and Westlothiana in the Viséan. Derived from a sister to Tulerpeton, Eldeceeon was basal to Diplovertebron and Solenodonsaurus in the LRT (Fig. 5). Relative to G. bohemicus, the skull of Eldeceeon was shorter and taller. The dorsal ribs are missing from the posterior half of the torso. This is an adaption to carrying larger eggs in gravid females. The pectoral girdle was more gracile. yet still deep. These two specimens nest together, but are distinct enough to warrant distinct species names.

Figure 5. Subset of the LRTfrom 2019 focusing on basal Archosauromorpha including Vaughnictis and Cabarzia nesting at the base of the Protodiapsid-Synapsid split. Note all the large varanopids nest together here in the Synapsida, separate from small varanopids in the Protodiapsida.

Add taxa
to see the big picture. That always solves problems. Taxon exclusion continues to be the number one problem in paleontology.

Don’t create reconstruction chimaeras.
That never works out well. Too often the chimaera is created freehand.

The LRT is free, online and worldwide,
just so workers can check out the current list of sister taxa pertinent to any taxon under study. Someday it will be used. Not this time, but someday.

More on Anthracosaurus
and the traditional clade ‘Anthracosauria’ follows below the References. This clade turns out to be much smaller than current textbooks and lectures might indicate. Anthracosaurus is a terminal taxon leaving no descendants tested in the LRT.

---

References
Ruta M, Clack JA and Smithson TR 2020. A review of the stem amniote Eldeceeon rolfei from the Viséan of East Kirkton, Scotland. Earth and Environmental Science Transactions of The Royal Society of Edinburgh (advance online publication)
DOI: https://doi.org/10.1017/S1755691020000079
Smithson TR 1994. Eldeceeon rolfei, a new reptiliomorph from the Viséan of East Kirkton, West Lothian, Scotland. Transactions of the Royal Society of Edinburgh: Earth Sciences 84 (3-4): 377–382.

wiki/Eldeceeon

Figure 3. The complete skull of Anthracosaurus greatly resembles its relative, Neopteroplax. These are basal flathead taxa with orbits high on the skull, distinct from reptilomorphs with smaller skulls and lateral orbits.

https://en.wikipedia.org/wiki/Anthracosauria
“Anthracosauria” is sometimes used to refer to all tetrapods more closely related to amniotes such as reptiles, mammals, and birds, rather than lissamphibians such as frogs and salamanders. An equivalent term to this definition would be Reptiliomorpha. Anthracosauria has also been used to refer to a smaller group of large, crocodilian-like aquatic tetrapods also known as embolomeres.

Gauthier, Kluge and Rowe (1988) defined Anthracosauria as a clade including “Amniota plus all other tetrapods that are more closely related to amniotes than they are to amphibians” (Amphibia in turn was defined by these authors as a clade including Lissamphibia and those tetrapods that are more closely related to lissamphibians than they are to amniotes).

Similarly, Michel Laurin (1996) uses the term in a cladistic sense to refer to only the most advanced reptile-like amphibians. Thus his definition includes Diadectomorpha, Solenodonsauridae and the amniotes.

Laurin (2001) created a different phylogenetic definition of Anthracosauria, defining it as “the largest clade that includes Anthracosaurus russelli but not Ascaphus true“. [Ascaphus is the extant tailed frog.]

Michael Benton (2000, 2004) makes the anthracosaurs a paraphyletic order within the superorder Reptiliomorpha, along with the orders Seymouriamorpha and Diadectomorpha, thus making the Anthracosaurians the “lower” reptile-like amphibians. In his definition, the group encompass the Embolomeri, Chroniosuchia and possibly the family Gephyrostegidae.

None of these apply to Anthrosaurus in the LRT.

Distinct from prior authors, the LRT recovers Limnoscelis, Diadectes and other diadectomorphs deep with the Lepidosauromorpha branch of the Reptilia. More taxa solved this problem, too.

3D pterosaur embryo video on YouTube

Willy Saíz created a 3D model of an unidentified genus pterosaur embryo
that appeared here on YouTube back in 2017. You can click the image to view the short video which silently rotates the image with lap dissolves adding muscles and skin.

It reminds me most
of the IVPP V 3758 specimen of the giant unnamed anurognathid embryo (Fig. 1). The embryo is a giant because it is nearly as large as most adult anurognathids (Fig. 2).

Figure 1. Click to enlarge. A magnitude of more detail was gleaned from this fossil (the IVPP egg/embryo) using the DGS method.

Unlike the Willy Saíz 3D model
the IVPP specimen (Figs. 1, 2) is partly disarticulated, including some of the skull bones. Evidently the leathery egg rolled or was dropped after the egg left the mother’s body, prior to burial and fossilization. Thankfully, due to its leathery shell, every bone stayed inside the ‘package’.

Also unlike the Saíz 3D model
the IVPP embryo had adult proportions (Fig. 2), a characteristic of all pterosaurs and all tritosaur lepidosaurs. Unfortunately, the Saíz 3D model has a large skull, tiny wings and tiny feet, traits not found in the IVPP embryo (Figs. 1, 2) or any other pterosaur embryo.

Figure 2. Click to enlarge. Anurognathids to scale. The adult of the IVPP embryo is 8x the size of the embryo, as in all other tested adult/embryo pairings.

Allometric traits are expected
only under the mythical and invalid archosaur hypothesis of pterosaur interrelationships unfortunately supported by the vast majority (= all but 1) of pterosaur workers. For example, Dr. Mark Witton, made the same mistake with a Pterodaustro embryo illustration (Fig. 3). Compare the imagined figure 3 to the traced figures 4 and 5.

Figure 3. Pterodaustro embryo as falsely imagined in Witton 2013. The actual embryo had a small cranium, small eyes and a very long rostrum. Compare to figures 4 and 5.

Are the Witton and Saíz illustrations examples of pseudoscience? 
They are not based on reality. They cannot be replicated, except by other imaginative artists. In science the intention and effort should always be to trace and replicate real data with precision (Figs. 1, 4) and thereafter create reconstructions from those tracings (Figs. 2, 5) with minimum freehand input. Unfortunately we live in a topsy-turvy world where precise tracings are considered pseudoscience by Dr. Witton (remember, he called me a crank) and other well-intentioned, but sadly mistaken scientists.

Figure 4. Original interpretations (2 frames black/white) vs. new interpretations (color).

Figure 5. Pterodaustro embryo. Note the adult proportions in most regards.

Let me know if you ever hear of 
paid professionals, like Dr. Darren Naish chastising and attempting to suppress the complete works of Dr. Mark Witton for promoting imagination in the guise of science. To my knowledge, that has not yet happened, and probably never crossed his mind due to alliances based on university affiliations.

How many referees and editors
tend to ‘let things slide’ based on the presence of a PhD or several co-authors? Several times a week oversights are caught here at PterosaurHeresies. Readers, this criticism of paleontology today is not pseudoscience. This is just the way things really are out there.

Postscript
If you have any doubts that Pterodaustro embryos had adult proportions, this growth series (Fig. 6) will quell those doubts.

Figure 6. The V263 specimen compared to other Pterodaustro specimens to scale.

‘Pennaraptora’ — avoid this junior synonym

A new volume published by the AMNH
(eds. Pittman and Xu 2020), is all about the the putative clade, ‘Pennaraptora’ (Fig. 1). According to the preface, “Pennaraptora comprises birds themselves as well as the pennaceous feathered dromaeosaurids, troodontids, scansoriopterygids, and oviraptorosaurians.”

Here
in the large reptile tree (LRT, 1727+ taxa; subset Fig. 2) scansoriopterygids are birds, not oviraptorosaurian sisters. Oviraptorosaurians are terminal taxa in a larger clade that includes therizinosaurs and the CNJ79 specimen of Compsognathus and that clade is the sister clade of the Compsognathus holotype, struthiomimids and tyrannosaurids (Fig. 2). The last common ancestor of all these clades in the LRT is Aorun zhaoi (Choiniere et al. 2013; IVPP V15709, Late Jurassic 161mya).

So this multipart study on ‘Pennaraptorans’ is off to several bad starts. Neither ‘Aorun‘, nor ‘Tyrannoraptora’ (see below) are mentioned in the text. Several taxa have been omitted from this clade, including the last common ancestor.

Only two generic taxa and “their last common ancestor (LCA)”
should be enough to define a clade. Look what bad things can happen when you use four suprageneric taxa (Fig. 1). Don’t let in generic taxa that do not belong and omit generic taxa that do belong. Even so, and surprisingly, all taxa employed here are clade members. Unfortunately the clades and a few taxa are a little mixed up due to taxon exclusion.

Figure 1. Cladogram of the Pennaraptora from Pittman and Xu eds. 2020. Color overlays added to show clades in the LRT (Fig. 2).

Foth et al. defined Pennaraptora in 2014.
“Pennaraptora is a clade defined as the most recent common ancestor of Oviraptor philoceratops, Deinonychus antirrhopus, and Passer domesticus (the house sparrow), and all descendants thereof,”  Again, this definition only needs the first two taxa. Passer nests within “all descendants thereof”. Even so, this is a definition we can work with (Fig. 2).

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

In the LRT ‘Pennaraptora’
is almost a junior synonym of Compsognathidae (Cope 1871; Fig. 2) because two specimens of Compsognathus are basalmost taxa. However, Aorun is the last common ancestor taxon. It was originally considered the oldest known coelurosaurian theropod and a juvenile.

Figure 3. Aorun compared to several other theropods to scale.

Figure 4. Aorun skull in situ and slightly restored. This is the basalmost tyrannoraptor in the LRT.

According to Wikipedia, Aorun is now considered a member of
the Tyrannoraptora (Sereno 1999) defined as, “Tyrannosaurus, Passer their last common ancestor [Aorun] and all of its descendants.” So Pennaraptora (2014) is a junior synonym of Tyrannoraptora (1999). The two define the same clade in the LRT and share a last common ancestor.

Coelurosauria (von Huene 1914 is defined as theropods closer to birds than to carnosaurs. In the LRT Tyrannoraptora is also a junior synonym for Coelurosauria.

---

References
Bidar AL, Demay L and Thomel G 1972b. Compsognathus corallestris,
une nouvelle espèce de dinosaurien théropode du Portlandien de Canjuers (Sud-Est de la France). Annales du Muséum d’Histoire Naturelle de Nice 1:9-40.
Choiniere JN, Clark JM, Forster CM, Norella MA, Eberth DA, Erickson GM, Chu H and Xu X 2013. A juvenile specimen of a new coelurosaur (Dinosauria: Theropoda) from the Middle–Late Jurassic Shishugou Formation of Xinjiang, People’s Republic of China. Journal of Systematic Palaeontology. online. doi:10.1080/14772019.2013.781067
Cope ED 1871. On the homologies of some of the cranial bones of the Reptilia, and on the systematic arrangement of the class. Proceedings of the American Association for the Advancement of Science 19:194-247
Foth C, Tischlinger H and Rauhut OWM 2014. New specimen of Archaeopteryx provides insights into the evolution of pennaceous feathers. Nature. 511 (7507): 79–82.
Huene F v 1914. Über de Zweistämmigkeit der Dinosaurier, mit Beiträgen zer Kenntnis einiger Schädel. Sep.-Abd. Neuen Jahrb. für Mineralogie Beil.-Bd.37:577–589. Pls. vii-xii.
Ostrom JH 1978. The osteology of Compsognathus longipes. Zitteliana 4: 73–118.
Peyer K 2006. A reconsideration of Compsognathus from the upper Tithonian of Canjuers, southeastern France, Journal of Vertebrate Paleontology, 26:4, 879-896.
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.
Wagner JA 1859. Über einige im lithographischen Schiefer neu aufgefundene Schildkröten und Saurier. Gelehrte Anzeigen der Bayerischen Akademie der Wissenschaften 49: 553.

wiki/Compsognathus
wiki/Tyrannoraptora
wiki/Aorun
wiki/Pennaraptora