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[dinosaur] Brachydectes (Lepospondyli) cranial morphology + Cretaceous Asia lizard tracks + snake (lizard (bug))

Ben Creisler

Some recent non-dino papers:

Jason D. Pardo &  Jason S. Anderson  (2016) 
Cranial Morphology of the Carboniferous-Permian Tetrapod Brachydectes newberryi (Lepospondyli, Lysorophia): New Data from µCT. 
PLoS ONE 11(8): e0161823. 

Lysorophians are a group of early tetrapods with extremely elongate trunks, reduced limbs, and highly reduced skulls. Since the first discovery of this group, general similarities in outward appearance between lysorophians and some modern lissamphibian orders (specifically Urodela and Gymnophiona) have been recognized, and sometimes been the basis for hypotheses of lissamphibian origins. We studied the morphology of the skull, with particular emphasis on the neurocranium, of a partial growth series of the lysorophian Brachydectes newberryi using x-ray micro-computed tomography (μCT). Our study reveals similarities between the braincase of Brachydectes and brachystelechid recumbirostrans, corroborating prior work suggesting a close relationship between these taxa. We also describe the morphology of the epipterygoid, stapes, and quadrate in this taxon for the first time. Contra the proposals of some workers, we find no evidence of expected lissamphibian synapomorphies in the skull morphology in Brachydectes newberryi, and instead recognize a number of derived amniote characteristics within the braincase and suspensorium. Morphology previously considered indicative of taxonomic diversity within Lysorophia may reflect ontogenetic rather than taxonomic variation. The highly divergent morphology of lysorophians represents a refinement of morphological and functional trends within recumbirostrans, and is analogous to morphology observed in many modern fossorial reptiles.


Kyung Soo Kim, Martin G. Lockley, Jong Deock Lim, Laura Pinuela, Lida Xing & Hae Won Moon (2016)
First report of lacertiform (lizard) tracks from the Cretaceous of Asia.
Cretaceous Research (advance online publication)
doi: http://dx.doi.org/10.1016/j.cretres.2016.08.013

The well-preserved trackway of a lacertiform, lizard-like trackmaker from the Haman Formation (Cretaceous) of Korea is described as Neosauroides koreaensis ichnogen. et ichnosp. nov. This is the only example of a Cretaceous lacertiform or lizard-like trackway currently known in the global track record. Although lacertiform trackways, mostly assigned to the ichnogenus Rhynchosauroides, are common in the global Triassic, they are almost entirely absent in the Jurassic and Cretaceous. Moreover, ichnological classification criteria allow that Neosaurioides is morphologically distinct from Rhynchosauroides at the genus level, and more like the tracks of the extant lizard Sceloporus. The reasons for the conspicuous lack of post-Triassic occurrences are not certain, but not due to a post-Triassic lack of potential lizard trackmakers. Thus, the preservation biases are likely due to paleobiological factors such as trackmaker ecology and paleoenvironmental preference.


Snake gut contains lizard with insect in its gut

Free pdf:

Krister T. Smith & Agustín Scanferla (2016)
Fossil snake preserving three trophic levels and evidence for an ontogenetic dietary shift.
Palaeobiodiversity and Palaeoenvironments (advance online publication)
DOI: 10.1007/s12549-016-0244-1

We report a fossil snake from the middle Eocene (48 Ma) Messel Pit, in whose stomach is a lizard, in whose stomach is an insect. This is the second known vertebrate fossil containing direct evidence of three trophic levels. The snake is identified as a juvenile of Palaeopython fischeri on the basis of new characters of the skull; the lizard is identified as Geiseltaliellus maarius, a stem-basilisk; and the insect, despite preserved structural colouration, could not be identified more precisely. G. maarius is thought to have been an arboreal species, but like its extant relatives may have foraged occasionally on the ground. Another, larger specimen of G. maarius preserves plant remains in the digestive tract, suggesting that omnivory in this species may have been common in larger individuals, as in extant Basiliscus and Polychrus. A general picture of the trophic ecology of P. fischeri is not yet possible, although the presence of a lizard in the stomach of a juvenile individual suggests that this snake could have undergone a dietary shift, as in many extant boines.