What is a limpkin? (genus: Aramus)

Figure 1. The limpkin (Aramus guarauna) is a basal member of the x family.

Figure 1. The limpkin (Aramus guarauna) is a long-legged, wading basal member of the x family.

Aramus guarauna (Linneaus 1766) is the extant limpkin. It is often considerd transitional between rails and cranes. In the large reptile tree (1121 taxa) the limpkin nests basal to seagulls and hummingbirds, plovers and crowned cranes, common cranes and stilts, terns and loons, kingfishers and jabirus, murres and penguins.

Figure 1. Skeleton of the limp kin (Aramus), traditionally nests within the crane and rail order Gruiformes.

Figure 2. Skeleton of the limpkin (Aramus), traditionally nests within the crane and rail order Gruiformes. In the LRT rails are not closely related, so Gruiformes should no longer include rails.

Extant limpkins eat snails.
Primitive limpkins like Aramournis  probably had a more diverse diet. It is known from a distal tarsus.

Traditional rails
like the corn crake (Crex) and the coot (Fulica) are much more basal birds that give rise to chickens, sparrows and parrots. Adding Rallus, the Virginia rail, to the LRT nests it between Aramus and the rest of the clade, which, phylogenetically makes hummingbirds, terns and penguins variations on the rail theme and Rallus at least a Middle Cretaceous taxon radiation.

Figure 4. Virginia rail alongside the rail clade in the LRT.

Figure 4. Virginia rail alongside the rail clade in the LRT.

Congeneric specimens of Aramus
are found in the Miocene, but more derived penguins are found in the Paleocene, pointing to a mid-Cretaceous radiation of this clade.

Limpkins are derived from Cretaceous sisters to
hamerkops (Scopus) and stone curlews (Burhinus), both long-legged taxa. By the evidence shown in the crown bird subset of the LRT (Fig. 4), long legs, like those shown by Aramus, the limpkin, are basal traits. The retention of hatchling short legs occurred several times by convergence, sometimes during the Cretaceous. See the earlier post on post K-T non-arboreal birds. 

Figure 4. Subset of the LRT focusing on the crown bird clade. Brown taxa are all long-legged. Neotony produces the smaller, shorter-legged, arboreal taxa.

Figure 4. Subset of the LRT focusing on the crown bird clade. Brown taxa are all long-legged. Neotony produces the smaller, shorter-legged, arboreal taxa.

References
Linneaus C von 1766. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio duodecima, reformata. pp. 1–532. Holmiæ. (Salvius)

wiki/Aramus_limpkin

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Bird, pterosaur, dinosaur simplified chronology

Following the earlier post on non-arboreal post K-T boundary birds…

…this one pretty much speaks for itself.
Here (Fig. 1) is a chronology, very much simplified, of birds, pterosaurs and dinosaurs according to the LRT.

Figure 1. Mesozoic chronology of bird, dinosaur and pterosaur clades.

Figure 1. Mesozoic chronology of bird, dinosaur and pterosaur clades based on taxa in the LRT.

If you’re curious about any of the taxa,
in the chronology, simply use Keywords to locate them.

Early Cretaceous stem chameleon/horned lizard

Unnamed stem chameleon (Daza et al. 2016; Early Cretaceous, 1.2cm in length; JZC Bu154; Fig. 1) is a tiny neonate preserved in amber. It also nests basal to horned lizards like Phrynosoma, in the large reptile tree (LRT, 1089 taxa). Note the long, straight hyoid forming the base of the shooting tongue. The split fingers and toes of extant chameleons had not yet developed in this taxon. Found in amber, this newborn lived in a coniferous forest.

Figure 1. The Early Cretaceous stem chameleon/horned lizard found amber. Snout to vent length is less than 11 mm. Much smaller than a human thumbnail.

Figure 1. The Early Cretaceous stem chameleon/horned lizard found amber. Snout to vent length is less than 11 mm. Much smaller than a human thumbnail. Insitu fossil from Daza et al. 2016,  colorized and reconstructed here. At a standard 72 dpi screen resolution, this specimen is shown 10x actual size.

This specimen further cements
the interrelationship of arboreal chameleons and their terrestrial sisters, the horned lizard we looked at earlier with Trioceros and Phyrnosoma in blue of this cladogram (Fig. 2) subset of the LRT.

Figure 3. Subset of the LRT focusing on the neonate stem chameleon/horned lizard.

Figure 2. Subset of the LRT focusing on the neonate stem chameleon/horned lizard.

Figure 6. Phyronosoma, the horned lizard of North America.

Figure 3. Phyronosoma, the horned lizard of North America.

Figure 2. Trioceros jacksonii overall. Size is 12 inches (30 cm) from tip to tip.

Figure 4. Trioceros jacksonii overall. Size is 12 inches (30 cm) from tip to tip.

References
Daza JD et al. 2016. Mid-Cretaceous amber fossils illuminate the past diversity of tropical lizards. Sci. Adv. 2016; 2 : e1501080 4 March 2016

New flightless and giant nyctosaurs: Alcione and Barbaridactylus

Scale bar problems
and a lack of reconstructions in the original paper are issues here.

Longrich, Martill and Andres 2018
bring us news of “a diverse pterosaur assemblage from the late Maastrichtian of Morocco that includes not only Azhdarchidae but the youngest known Pteranodontidae and Nyctosauridae. [This] dramatically increases the diversity of Maastrichtian pterosaurs. At least 3 families —Pteranodontidae, Nyctosauridae, and Azhdarchidae — persisted into the late Maastrichtian. These patterns suggest an abrupt mass extinction of pterosaurs at the K-Pg boundary.”

The authors summary starts off with an invalid statement:
“Pterosaurs were winged cousins of the dinosaurs.”  That was invalidated by Peters 2000, 2007 and ignored every since. We looked at that problem earlier here, here and here in a 3-part series testing all candidates. It’s time to realize that no one will ever find pterosaur kin among the dinos. They’ve already been clearly identified among the lepidosaurs.

The authors failed to include the Maastrictian tupuxuarid
found in southern Texas (Fig. 1; TMM 42489-2) and did not consider the Maastrichtian footprints discovered in 1954 and reexamined in 2018 that include two ctenochasmatids we will look at tomorrow.

TMM 42489-2, the tall crested Latest Cretaceous large rostrum and mandible. It's a close match to that of Tupuxuara, otherwise known only from Early Cretaceous South American strata.

Figure 1. TMM 42489-2, the tall crested Latest Cretaceous large rostrum and mandible. It’s a close match to that of Tupuxuara, otherwise known only from Early Cretaceous South American strata.

Alcione elainus gen. et sp. nov.
The new 1.5x larger nyctosaurid, Alcione elainus, known from disassociated bones including a shorter radius + ulna, a shorter metacarpal 4, a larger femur, and a tiny sternal complex (identified as a ‘sternum’ in the text) only 40 percent the size of a standard nyctosaur sternal complex (if the scale bars are correct). When placed on a reconstruction of a more complete Nyctosaurus (UNSM 93000; Fig. 2), scaled to the humerus, the result produces a likely flightless nyctosaur. Strangely, the authors called this a “small nyctosaur” even though it is half again larger than UNSM 93000. The authors mislabeled the shorter, straighter scapula as a coracoid, and vice versa.

Figure 2. GIF movie of Nyctosaurus and Alcione showing a likely flightless nyctosaur based on the parts preserved.

Figure 2. GIF movie of Nyctosaurus and Alcione showing a likely flightless nyctosaur based on the parts preserved. Three frames change every 5 seconds. The sternum is tiny (assuming the scale bars are correct), the metacarpus and antebrachium are short and the femur is long.

They did not mention the possibility of flightlessness.
They did report, “The abbreviated distal wing elements in Alcione indicate a specialized flight style. The short, robust proportions suggest reduced wingspan and increased wing loading, implying distinct flight mechanics and an ecological shift. Short wings would increase lift-induced drag at low speeds, but reduced wing areas would decrease parasite drag at high speeds, suggesting that Alcione may have been adapted for relatively fast flapping flight compared to other nyctosaurids. Alternatively, reductions in wingspan might represent an adaptation to underwater feeding, i.e., plunge diving of the sort practiced by gannets, tropicbirds, and kingfishers, where smaller wings would reduce drag underwater.”

Not sure why they mentioned
‘distal wing elements’ here. They did not list or discuss distal wing elements elsewhere. Perhaps they meant proximal.

The reconstructed mandible of Alcione
is narrower than the rostrum in UNSM 93000.

Based on the vestigial fingers of UNSM 93000
and the short metacarpus of the new specimen, Alcione might have been the first pterosaur to walk on metacarpal 4, albeit at the very end of the reign of pterosaurs.

Other flightless pterosaurs include:
the basal azhdarchid form the Solnhofen, Jme-Sos 2428 and the Late Jurassic anurognathid PIN 2585/4 from the Sordes slab. They demonstrate that the distal wing elements reduce first. Thus the reconstruction, based on nyctosaur patterns restores a wing that was not volant.

Longrich, Martill and Andres did find a giant nyctosaur
which they named Barbaridactylus grandis based on a large humerus (Fig. 3). The humerus of the more complete UNSM 93000 specimen is 9.5 cm. By comparison the humerus in Barbaridactylus is 22.5 cm. I’m going to trust the text comment that the ulna + radius are 1.3x longer than the humerus. The scale bars indicate about half that length. Similar problem possible in the scapula/coracoid, according to the nyctosaur bauplan.

Figure 3. Barbaridactylus, a giant nyctosaurid. If the wing was like UNSM 93000, then it could fly. If the wing was like Alcione, then it could not. The scale bars did not match the text description on the ulna + radius, so both sizes are shown.

Figure 3. Barbaridactylus, a giant nyctosaurid. If the wing was like UNSM 93000, then it could fly. If the wing was like Alcione, then it could not. The scale bars did not match the text description on the ulna + radius, so both sizes are shown. Sometimes you have to be prepared for the occasional mistake in a published paper.

Other giant nyctosaurs
Earlier and here we noted giant nyctosaurs were flying over the Niobrara Sea (midwest North America) based on a large wing finger with unfused extensor tendon process (YPM 2501) and a large nyctosaur pelvis (KUVP 993; misinterpreted by Bennett (1991, 1992) as belonging to a female Pteranodon). 

No reconstructions were provided
by Longrich, Martill and Andres 2018. Reconstructions and a nyctosaur blueprint might have helped these paleontologists with firsthand access to the specimens discover the issues they missed.

It’s good to know
more pterosaurs made it to the latest Cretaceous.

References
Bennett SC 1991. Morphology of the Late Cretaceous Pterosaur Pteranodon and Systematics of the Pterodactyloidea. [Volumes I & II]. Ph.D. thesis, University of Kansas, University Microfilms International/ProQuest.
Bennett SC 1992.
 Sexual dimorphism of Pteranodon and other pterosaurs, with comments on cranial crests. Journal of Vertebrate Paleontology 12: 422–434.
Longrich NR, Martill DM, Andres B 2018.
Late Maastrichtian pterosaurs from North Africa and mass extinction of Pterosauria at the Cretaceous-Paleogene boundary. PLoS Biol 16(3): e2001663. https://doi.org/10.1371/journal.pbio.2001663
Peters D 2000b. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.
Peters D 2007. 
The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.

Press coverage
Smithsonian
Newswise
PhysOrg

Parrot mimic from the Early Cretaceous

This fossil can be found
(Figs. 1, 2) in the Jeholornis Wikipedia page, labeled Shenzhouraptor. It’s interesting because the rostrum of this Early Cretaceous bird (with impressed feathers) has a downturned tip unlike that of any local taxon. Of course the dentary turns down anteriorly to fit it, as in the convergent parrot, Ara (Fig. 3). I don’t know what the museum number is, nor do I have any reference works that name the genus and species.

Figure 1. What is the museum number and latest generic label for this specimen?

Figure 1. What is the museum number and latest generic label for this specimen?

Here
(subset Fig. 3) it nests with the larger Jeholornis in the large reptile tree (LRT, 1068 taxa). Both are scansoriopterygids.

Figure 2. The Hong Kong specimen attributed to Shenzhouraptor reconstructed from a low-rez image.

Figure 2. The Hong Kong specimen attributed to Shenzhouraptor reconstructed from a low-rez image. If higher resolution is available, please send it along. There is much I am guessing at here. Not sure how to interpret the rostrum based on the presently crappy data. The scale bar is inaccurate.

Figure 3. Scansoriopterygidae includes two Solnhofen birds traditionally labeled Archaeopteryx, but clearly distinct genera. Note, none of these taxa have a styliform bone, as originally figured in Yi qi.

Figure 3. Scansoriopterygidae includes two Solnhofen birds traditionally labeled Archaeopteryx, but clearly distinct genera. Note, none of these taxa have a styliform bone, as originally figured in Yi qi.

By convergence,
The parrot, Ara (below), has features similar to those first appearing in the Hong Kong specimen. Note the deep robust mandible and the ascending jugal, separating the orbit from the conjoined temporal fenestra, making the skull stronger for cracking seeds.

Figure 4. Skull of Ara macao with bones colored.

Figure 4. Skull of Ara macao with bones colored.

References
Looking for them now.

https://en.wikipedia.org/wiki/Jeholornis

Basal mammals: Guess what they evolved to become.

Can you guess
(or do you know) which of these taxa evolved to become a human? a killer whale? a rabbit? a giraffe? a bat? a pangolin?

Figure 1. Can you guess which of these taxa evolved to become a human? a killer whale? a rabbit? a giraffe?

Figure 1. Can you guess which of these taxa evolved to become a human? a killer whale? a rabbit? a giraffe?

H. Onychodectes – basal to all large herbivorous mammals, including giraffes.

G. Maelestes – basal to tenrecs and toothed whales.

F. Tupaia – basal to the gnawing clade including rodents and rabbits.

E. Ptilocercus – basal to Primates, including humans (but note the loss of all premaxillary teeth in this extant taxon).

D. Palaechthon – basal to flying lemurs, bats and pangolins.

C. Monodelphis – basal to all placental mammals.

B. Asioryctes – basal to Monodelphis and all placental mammals.

A. Eomaia – basal to all therian mammals (placentals + marsupials).

These are the basalmost taxa
in various clades of Eutherian (placental) mammals. Not a lot of difference to start (which makes scoring difficult). So much potential at the end. Eomaia goes back to the Early Cretaceous, so it’s not difficult to imagine the radiation of these taxa throughout the Cretaceous.

This falls in line with
the splitting of the African golden mole (Chrysochloris) from its South American sister, Necrolestes, a diversification, migration and split that had to happen before Africa split from South American in the Early Cretaceous.

Sharp-eyed readers
will note the re-identification of bones and teeth in Palaechthon, Ptilocercus and Tupaia. It’s been a long weekend trying to figure out long-standing problems in this portion of the LRT. Some of these taxa were some of the first studied and my naiveté was the source of the earlier disinformation, now corrected. If you see any errors here, please advise and, if valid, repairs will be made.

… and Liaoconodon is not a mammal…

Yesterday we noted that Repenomamus was not a mammal, but nested with the stem- (pre-) mammal tritylodontids, like Pachygenelus. Today Liaoconodon hui (Meng, Wang and Li 2011; IVPP V 16051; early Cretaceous, Aptian, 120 mya), is also not a eutriconodont mammal, but nests between Probainognathus and Pachygnenelus a little deeper into the phylogeny of the Cynodontia in the large reptile tree.

Figure 1. Liaocondon skull traced and reconstructed. In the LRT it most closely resembles that of Probainognathus.

Figure 1. Liaocondon skull traced and reconstructed. In the LRT it most closely resembles that of Probainognathus. Note the enormous size of the temporal fenestrae, the downturned squamosals and postdentary bones, all shared with Probainognathus. 

Liaconodon lacks a coronoid
and the scapula has a ventral glenoid, which are traditional mammal traits. It also has a mammal-like ilium without a posterior process, like a mammal… or a pre-mammal tritylodontid, like Oligokyphus and Kayentatherium. Once again the narrow braincase of Liaconodon, like that of Repenomamus, tells us this is a pre-mammal.

Figure 2. Probainognathus skull(s) in several views along with a pectoral and pelvic girdle.

Figure 2. Probainognathus skull(s) in several views along with a pectoral and pelvic girdle. The lack of a femoral head neck is a trait shared with Liaoconodon. 

Liaconodon lacks large canines
and the lower incisors are quite enlarged. The postorbital bar does not appear to be complete, but the prefrontal, postfrontal and postorbital are still visible and unfused to other bones, as in Probaingnathus.

Figure 3. Liaoconodon in situ.

Figure 3. Liaoconodon in situ. The causals are similar in shape to those of Castrocauda. 

Jin Meng of the AMNH
made a video posted to YouTube describing how ground-breaking it was to find post dentary bones in Liaconodon, which they considered a mammal. Those post-dentary bones are indeed clear and articulated, but par for the clade in pre-mammal cynodonts.

The manus and pes are well preserved
which is something we rarely see around this node. The caudals are nearly identical to those of Castrocauda. The femora were likewise rather short.

It was a good week for finding errors.
As before, we all boggled this one. To those who are toying with the challenge I presented earlier about finding badly nested taxa in the LRT, sorry, you missed this one.

References
Meng J, Wang Y-Q and Li C-K 2011. Transitional mammalian middle ear from a new Cretaceous Jehol eutriconodont. Nature 472 (7342): 181–185.

wiki/Liaoconodon