Basal turtles with a lateral temporal fenestra

Today let’s look at
Glyptops plicatulus (Marsh 1890; AMNH 336; Late Jurassic), an associated skull, shell, and partial skeleton (Fig. 1). Gaffney (1979) reported, “The poor preservation of the skulls precludes a detailed study of the skull roof.” That may be true. Or not. Bones appear to be lost from the temporal regions, but every temporal bone can be identified, just smaller.

Apparently Glyptops had large skull openings
like other turtles. Here the temporal bones were reduced, leaving lateral and suparaoccipital openings, like other turtles. A DGS tracing (Fig. 1) and reconstruction (Fig. 2) provide one solution. Perhaps not the only solution, but one worth considering because no bones are missing here (contra Gaffney 1979).

Figure 1. Glyptops, a basal hard-shell turtle in several views. All data from Gaffney 1979 except the color overlays, which are applied here and used to make the reconstruction in figure 2.

Figure 1. Glyptops, a basal hard-shell turtle in several views. All data from Gaffney 1979 except the color overlays, which are applied here and used to make the reconstruction in figure 2.

According to Gaffney (1979), “their sole unique feature an elongate basisphenoid extending the length of and completely separating the pterygoids.”

Figure 2. Glyptops skull reconstructed from color overlays in figure 1. Note the semi-fenestrated skull mimicking the diapsid configuration.

Figure 2. Glyptops skull reconstructed from color overlays in figure 1. Note the semi-fenestrated skull mimicking the diapsid configuration that Gaffney considered poorly preserved. Gray areas are restored based on sister taxa.

Many traits presage the appearance of traits
in derived turtles, like Terrapene, the Eastern box turtle, by convergence. The two are not directly related to one another, despite sharing several traits. In Glyptops the frontals (lavender) were separated from the parietals (amber) by intervening postfrontals (orange) and postorbitals (aqua) that meet at the midline.

Figure 3. Subset of the large reptile tree (LRT, 1199 taxa) with the addition of three basal turtles

Figure 3. Subset of the large reptile tree (LRT, 1300 taxa) with the addition of three basal turtles

Other turtles that have lateral temporal fenestrae
include the leatherback sea turtle, Dermochelys (Fig. 3, we looked at yesterday), and Meiolania (Fig. 4, now basal to Proganochelys) by convergence.

Figure 2. Skull of Dermochelys adult and juvenile demonstrating the lengthening of the temporal region during maturity. The lateral temporal fenestra appears between the squamosal and quadrate.

Figure 4. From yesterday’s blogpost, the skull of Dermochelys adult and juvenile demonstrating the lengthening of the temporal region during maturity. The lateral temporal fenestra appears between the squamosal and quadrate.

So some turtles are anapsids,
(reptiles that lack temporal openings). Others are not. None are phylogenetic diapsids, despite having large skull openings (Fig. 1) from the top and the sides.

These exceptions remind us
not to define reptiles by their traits (although most of the time this method works well), but rather by their phylogenetic placement (Fig. 3), a method that always works.

Figure 1. Meiolania has a lateral temporal fenestra created by more bone encircling the tympanum (ear drum) at the quadrate. It could be that the top of the qj is actually the fused sq.

Figure 5. Meiolania has a lateral temporal fenestra created by more bone encircling the tympanum (ear drum) at the quadrate, not related to the other temporal openings that start at the back or the bottom of the skull.

Tomorrow,
more laterally fenestrated turtles.

References
Gaffney ES 1979. The Jurassic Turtles of North America. Bulletin of the American Museum of Natural History 162(3):91-136.
Marsh OC 1890. Notice of some extinct Testudinata. American Journal of Science ser. 3, vol. 40, art. 21: 177–179.

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The leatherback sea turtle: alone no longer

The leatherback turtle
(genus: Dermochelys) is different from all other sea turtles. It is the only extant genus of the family Dermochelyidae, the sister family to other sea turtles.

Dermochelys coriacea (Vandelli 1761, originally Testudo; Blainville 1816) lacks a bony shell (Fig. 1), replaced by thick, oily, leathery skin. The mouth and esophagus are filled with backward pointing spikes arising from toothess jaws (Fig. 1). Here (Fig. 2) a juvenile skull demonstrates the elevation and lengthening of the postorbital region in the adult.

Figure 2. Dermochelys skeleton, ventral view. In vivo (upper left) and open mouth (lower right).

Figure 1. Dermochelys skeleton, ventral view. In vivo (upper left) and open mouth (lower right).

Note the lack of temporal emargination
in the skull of Dermochelys (Fig. 2). That turns out to not be such a big deal in turtle evolution. The invagination occurred several times in turtles by convergence. This is something one finds out by phylogenetic analysis—if you don’t have an initial bias.

Figure 2. Skull of Dermochelys adult and juvenile demonstrating the lengthening of the temporal region during maturity. The lateral temporal fenestra appears between the squamosal and quadrate.

Figure 2. Skull of Dermochelys adult and juvenile demonstrating the lengthening of the temporal region during maturity. The lateral temporal fenestra appears between the squamosal and quadrate.

Alone no longer.
In the large reptile tree (LRT, 1200 taxa), the freshwater turtle Carettochelys (Fig. 3, 4; Ramsay 1886; 70 cm) nests with Dermochelys. Brinkman, Rabi and Zhao 2017 nested Carettochelys basal to soft shell turtles, unaware that soft shell turtles had a separate origin among small horned pareiasaurs. Like the soft-shell turtle, Trionyx, the soft nose tissue of Carettochelys extends slighly from the skull (Fig. 4) by convergence. Dermochelys (Fig. 1) does not have this proboscis.

Figure 5. Carettochelys skull in two views. Bones colored here.

Figure 3. Carettochelys skull in two views. Bones colored here. Note the long, upturned premaxilla. The invagination of the temporal region is convergent with several other clades of turtles. The supratemporal is orange. The squamosal is lavender. The quadratojugal is a vestige on the posterior maxilla. Compare to figure 2.

The pig-nosed turtle
(genus: Carettochelys) is also unique. It is the only freshwater turtle with flippers. The carapace is not scaly, but leathery (hmm, where have we hear that before?) over bone (Fig. 5).

Despite their differences
Carettochelys and Dermochelys find no closer sisters in the LRT than with each other.

FIgure 1. Carettochelys, the pig-nose turtle, is a freshwater form with flippers, like marine turtles, by convergence.

Figure 4. Carettochelys, the pig-nose turtle, is a freshwater form with flippers, like marine turtles, by convergence.

Why was this not discovered earlier?
Mistaking the supratemporal for the squamosal was only part of the problem. Fusion of the skull bones in turtles (as in birds) gives paleontologists trouble. The dual origin of turtles was not previously considered a possibility.

Figure 1. Carettochelys in 3 views from Digimorph.org and used with permission.

Figure 5. Carettochelys in 3 views from Digimorph.org and used with permission. The leatherback lost its bony carapace.

When workers expand their taxon list
they will recover what the LRT recovers. Until now (Fig. 6), unfortunately, that has not happened.

Figure 3. Subset of the large reptile tree (LRT, 1199 taxa) with the addition of three basal turtles

Figure 6. Subset of the large reptile tree (LRT, 1199 taxa) with the addition of three basal turtles

References
Brinkman D, Rabi M and Zhao L-J 2017. Lower Cretaceous fossils from China shed light on the ancestral body plan of crown soft-shell turtles (Trionychidae, Cryptodira). Nature Scientific Reports 7(6719).
Gaffney ES 1979. Comparative cranial morphology of recent and fossil turtles. Bulletin of the American Museum of Natural History 164(2):65-376.
Ramsay EP 1886. On a new genus and species of fresh water tortoise from the Fly River, New Guinea. Proceedings of the Linnaean Society of New South Wales (2) 1: 158-162.

wiki/Carettochelys
wiki/Dermochelys

Dermochelys and Carettochelys in ReptiliaEvolution.com

 

Kallokibotion: a late-surviving, basal, hard-shell turtle

A recent paper by Pérez-Garcia and Codrea 2018
on the basal, but late-surviving turtle, Kallokibotion bajazidi, (Nopsca 1923a,b) brings us more specimens and more hypotheses of turtle relationships. This taxon has been described as ‘an enigma’, perhaps because all currently known specimens combine Late Triassic traits with a Latest Cretaceous occurrence The visibility of the naris in lateral view goes back to the pre-turtle, Elginia. Transitional taxa, like Meiolania (Fig. 2) and Proganochelys, do not have this trait. Essentially this taxon links the Proganochelys clade to all later hard-shell turtles. (Remember, soft-shell turtles had a separate origin).

FIgure 1. The UBB-ToK2 specimen of Kallkibotion as originally interpreted and here reinterpreted with colors. Note the former squamosal is now the supratemporal, as in all turtles and pareiasaurs.

FIgure 1. The UBB-ToK2 specimen of Kallkibotion as originally interpreted and here reinterpreted with colors. Note the former squamosal is now the supratemporal, as in all turtles and pareiasaurs. Sometimes skull grooves match sutures. Sometimes they cross sutures.

Gaffney and Meylan 1992 report, “Kallokibotion is a cryptodire because it has the otic trochlea synapomorphy of cryptodires, and it is a member of the Selmacryptodira because it has a posterior pterygoid process under the middle ear. It lacks the posterior temporal emargination synapomorphic of the Daiocryptodira and lies outside that group.”

I’m not going to discuss the suprageneric taxa listed above
because no prior turtle phylogenies recognized the diphyletic nature of soft-shell and hard-shell turtles.

Figure 3. Subset of the large reptile tree (LRT, 1199 taxa) with the addition of three basal turtles

Figure 2. Subset of the large reptile tree (LRT, 1199 taxa) with the addition of three basal turtles

Kallokibotion links
Niolamia and Miolania (Fig. 3 )with higher turtles, skipping over Proganochelys (Late Triassic, Fig. 4), the traditional baalmost turtle.

 

Figure 2. Comparing Kallokbotion and Meiolania. Note: the traditional squamosal is here the supratemporal. The origin of Kallokibotion can be attributed to neotony.

Figure 3. Comparing Kallokbotion and Meiolania. Note: the traditional squamosal is here the supratemporal. The origin of Kallokibotion can be attributed to neotony in this hypothesis of interrelationships.

Figure 2. The skull of Proganochelys, a basal turtle without skull invagation and without horns.

Figure 4. The skull of Proganochelys, a basal turtle close to Kallokibation, Note the squamosal and supratemporal and compare those to Kallokibation in  Fig. 1.

Kallokibotion was recognized as a member of Meiolaniformes
in several recently published papers (see Rabi et al., 2013b; Sterli & de la Fuente, 2013; Sterli et al., 2015a, b). Chubutemys is considered a meiolaniform without horns, but workers who proposed this clade did not realize meiolaniids were basalmost hard-shell turtles.

Figure 2. Kallokibation carapace and plastron from Gaffney and Melton 1992.

Figure 5. BMNH R4918 specimen of Kallokibation carapace and plastron from Gaffney and Melton 1992. This is the first of the tested taxa that has a short, unarmored tail. The skull was relatively small and unarmored.

Pérez-Garcia and Codrea 2018
discovered new specimens (Fig. 1) that “not only reveal detailed cranial and postcranial elements poorly known until now, refuting previous hypotheses about the anatomy of this taxon, but also allow us to identify numerous hitherto unknown characters.” The new information, “shows Kallokibotion as the sister taxon of the crown Testudines.”

A lot of discussion about crown-group turtles goes out the window
when taxa are included that split hard from soft-shell taxa before turtles had shells. Thus all known turtles, and several non-turtle pareiasaurs, fall under the current definition of crown turtles in the LRT.

Pérez-Garcia and Codrea had no idea what turtles are.
They nest the pre-lepidosauriform, Owenetta, the pareiasaur, Anthodon, the plesiosaur, Simosaurus, and the rhynchocephalian, Sphenodon as progressively more distant outgroup taxa. Throw those out and, except for the meiolanids, their pruned turtle cladogram is similar to the same subset of the LRT.

Here 
(Fig. 3) Kallokibotion does indeed nest close to the meiolanids and Kayentachelys, but other taxa intervene. The loss of horns and a long armored tail on higher hard-shell turtles, like Kallokibotion, can be attributed to neotony.

References
Dyke GJ et al. (20 co-authors) 2014. Thalassodromeus sebesensis—a new name for an old turtle. Comment on ‘Thalassodromeus sebesensis, an out of place and out of time Gondwanan tapejarid pterosaur’, Grellet-Tinner and Codrea. Gondwana Research. doi:10.1016/j.gr.2014.08.004.
Gaffney ES and Meylan PA 1992. The Transylvanian turtle, Kallokibotion, a primitive cryptodire of Cretaceous Age. American Museum Novitates (3040).
Nopcsa F 1923a. On the geological importance of the primitive reptilian fauna of the Uppermost Cretaceous ofHungary; with a description of a new tortoise (Kallokibotion). Quart. Jour. Geol. Soc. 79(1): 100—116.
Pérez-García A and Vlad Codrea 2018. New insights on the anatomy and systematics of Kallokibotion Nopcsa, 1923, the enigmatic uppermost Cretaceous basal turtle (stem Testudines) from Transylvania. Zoological Journal of the Linnean Society. 182(2):419–443. doi:10.1093/zoolinnean/zlx037.
Zhou CF et al. 2015. A sinemydid turtle from the Jehol Biota provides insights into the basal divergence of crown turtles, Scientific Reports (2015). DOI: 10.1038/srep16299

Read more at:
https://phys.org/news/2015-11-insights-family-tree-modern-turtles.html#jCp
wiki/Kallokibotion
https://www.earthmagazine.org/article/trouble-turtles-paleontology-crossroads

Germanodactylus sp. 6592 plate and counterplate

Matching a fossil plate to a counterplate is easy.
Matching a photo of a plate to a photo of counterplate (Fig. 1) requires Photoshop, even if the differences are minute.

Figure 1. Plate and counterplate of the SMNS 6592 specimen referred to Germanodactylus matched in Photoshop.

Figure 1. Plate and counterplate of the SMNS 6592 specimen referred to Germanodactylus matched in Photoshop.

This is the first time I’ve seen
the counterplate to the SMNS 6592 specimen attributed to Germanodactylus. And I think this counterplate is composed of painted plaster. Photoshop was used to match the plate to the counterplate and to trace the resulting elements. As you can see, the pelvis is in an atypical position due to taphonomy (crash landing on its butt?), but everything else seems to be naturally posed with the exception of the displaced and overlapping femora (another results of the crash landing, perhaps).

Maybe the best way to compare congeneric taxa

Online presentations
have certain advantages over published books and journals. What you’ll see today could be more widely presented in the future as biology, morphology and phylogeny move from books and journals to the Internet, complete with inexpensive animation, transparency and lap dissolves.

Figure 1. GIF movie of tiger and leopard skulls for comparison. See text for details.

Figure 1. GIF movie of tiger and leopard skulls for comparison. See text for details.

Obviously related to one another,
but isolated geographically to produce distinct species, the tiger (Panthera tigris) and the leopard (Panthera pardus, Fig. 1) are interesting to compare one skull with another. A GIF movie makes comparisons easy to see. A roll-over would be easier to handle, but roll-overs are not permitted on WordPress.com sites yet.

A giant Romanian pterosaur mandible fragment

FIgure 1. LPB R 2347 largest pterosaur mandible compared to Bakonydraco.

FIgure 1. LPB R 2347 largest pterosaur mandible compared to Bakonydraco.

Vremir et al. 2018
describe a pterosaur mandible fragment (Figs. 1, 2), “This specimen represents the largest pterosaur mandible ever found and provides insights into the anatomy of the enigmatic giant pterosaurs.”

Figure 2. LPR pterosaur mandible compared to related taxa, like Eopteranodon, and to the largest known pterosaur, Quetzalcoatlus. Figure 2. LPR pterosaur mandible compared to related taxa, like Eopteranodon, and to the largest known pterosaur, Quetzalcoatlus.

Figure 2. LPR pterosaur mandible compared to related taxa, like Eopteranodon, and to the largest known pterosaur, Quetzalcoatlus to scale.

It’s worthwhile
to place the jaw fragment in context with other pterosaurs. We don’t have a similar jaw fragment for the big Quetzalcoatlus (Fig. 2), which likely stood twice as tall as the giant eopteranodontid owner of the jaw fragment. Bakonydraco is a likely eopteranodontid, larger than Eopteranodon, but much smaller than the jaw fragment owner.

Earlier this jaw fragment was used as the basis for restoring the rest of this pterosaur as a giant azhdarchid nicknamed, ‘Dracula’ (with beaucoup errors, Fig. 2).

Figure 1. Dracula the giant azhdarchid pterosaur museum mount. Hopefully it's not too late to fix the problems here.

Figure 2. Dracula the giant pterosaur model built and based on the jaw fragment in today’s post. That’s a lot of imagination!

References
Vremir M et al. 2018. Partial mandible of a giant pterosaur from the uppermost Cretaceous (Maastrichtian) of the HaÈeg Basin, Romania. Lethaia doi: https://doi.org/10.1111/let.12268 https://onlinelibrary.wiley.com/doi/abs/10.1111/let.12268

Switching pedal phalanges on Sylviornis

According to Worthy et al. 2016
“Numerous phalanges are known for Sylviornis neocaledoniae. While no articulated material is known, the collection reveals that this bird had the usual digital formula of 2:3:4:5 for digits I to IV as shown in a composite set (Fig 11, here Fig. 1) assembled based on matching size of the elements from The Pocket, in Cave B.”

Figure 1. By switching two phalages (2.1 and 4.1) you get a pes that includes a p3.1>p2.1 as in all sister taxa. This minor change is revealed by phylogenetic analysis.

Figure 1. By switching two phalages (2.1 and 4.1) you get a pes that includes a p3.1>p2.1 as in all sister taxa. Note the red PIL intersecting the joint when repaired. This minor change is revealed by phylogenetic analysis. Image modified from Worthy et al. 2016. Cave bones, like this, can sometimes be scattered.

Sylviornis neocaledoniae (Poplin 1980, recently extinct) was originally considered a ratite, then a megapode, then a stem chicken (Gallus), not quite a meter in length. Here it nests at the base of the hook-beaked predatory birds between Sagittarius and Cariama. The premaxilla forms a crest. The narrow rostrum is mobile relative to the wide cranium. We looked at Sylviornis earlier here.

Figure 1. Sylviornis is not a giant chicken. It's a basal predatory bird.

Figure 1. Sylviornis figure with original pedal phalangeal setup.

On a similar note…
I found this skeleton of Phoenicopterus, the flamingo (Fig. 3), with its toes switched on this unknown museum mount. The preparators should have mounted digit 2 medially and digit 4 laterally.

Figure 2. Flamingo skeleton with toes switched. Pedal 2 should be medial. Pedal 4 should be lateral.

Figure 2. Beautiful flamingo skeleton with toes switched. Pedal 2 should be medial. Pedal 4 should be lateral. Science is at its best when it is both appreciative and critical.

References
Poplin F 1980. Sylviornis neocaledoniae n. g., n. sp. (Aves), ratite éteint de la Nouvelle-Calédonie. Comptes Rendus de l’Académie des Sciences, Série D (in French). 290: 691–694.
Worthy TH et al. 2016. Osteology Supports a Stem-Galliform Affinity for the Giant Extinct Flightless Bird Sylviornis neocaledoniae (Sylviornithidae, Galloanseres). PLoS ONE 11(3): e0150871. doi:10.1371/journal.pone.0150871

wiki/Sylviornis