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Re: Crocodylian micro-sense-organs (free pdf) and fruit eating, plus other non-dino papers



From: Ben Creisler
bcreisler@gmail.com



Sorry for listing the first paper. I already posted it a few weeks ago
and forgot. The rest of the papers are new.

http://dml.cmnh.org/2013Jul/msg00018.html

On Tue, Jul 23, 2013 at 9:02 PM, Ben Creisler <bcreisler@gmail.com> wrote:
> From: Ben Creisler
> bcreisler@gmail.com
>
> A number of recent non-dino papers that may be of interest:
>
>
> Nicolas Di-Poï & Michel C, Milinkovitch (2013)
> Crocodylians evolved scattered multi-sensory micro-organs.
> EvoDevo (advance online publication)
> DOI: 10.1186/2041-9139-4-19
> http://link.springer.com/article/10.1186/2041-9139-4-19
> Open Access!
>
> Background
> During their evolution towards a complete life cycle on land, stem
> reptiles developed both an impermeable multi-layered keratinized
> epidermis and skin appendages (scales) providing mechanical, thermal,
> and chemical protection. Previous studies have demonstrated that,
> despite the presence of a particularly armored skin, crocodylians have
> exquisite mechanosensory abilities thanks to the presence of small
> integumentary sensory organs (ISOs) distributed on postcranial and/or
> cranial scales.
>
> Results
> Here, we analyze and compare the structure, innervation, embryonic
> morphogenesis and sensory functions of postcranial, cranial, and
> lingual sensory organs of the Nile crocodile (Crocodylus niloticus)
> and the spectacled caiman (Caiman crocodilus). Our molecular analyses
> indicate that sensory neurons of crocodylian ISOs express a large
> repertoire of transduction channels involved in mechano-, thermo-, and
> chemosensory functions, and our electrophysiological analyses confirm
> that each ISO exhibits a combined sensitivity to mechanical, thermal
> and pH stimuli (but not hyper-osmotic salinity), making them
> remarkable multi-sensorial micro-organs with no equivalent in the
> sensory systems of other vertebrate lineages. We also show that ISOs
> all exhibit similar morphologies and modes of development, despite
> forming at different stages of scale morphogenesis across the body.
>
> Conclusions
> The ancestral vertebrate diffused sensory system of the skin was
> transformed in the crocodylian lineages into an array of discrete
> multi-sensory micro-organs innervated by multiple pools of sensory
> neurons. This discretization of skin sensory expression sites is
> unique among vertebrates and allowed crocodylians to develop a
> highly-armored, but very sensitive, skin.
>
> ===
>
>
> S. G. Platt, R. M. Elsey, H. Liu, T. R. Rainwater, J. C. Nifong, A. E.
> Rosenblatt, M. R. Heithaus & F. J. Mazzotti (2013)
> Frugivory and seed dispersal by crocodilians: an overlooked form of 
> saurochory?
> Journal of Zoology (advance online publication)
> DOI: 10.1111/jzo.12052
> http://onlinelibrary.wiley.com/doi/10.1111/jzo.12052/abstract
>
> Saurochory (seed dispersal by reptiles) among crocodilians has largely
> been ignored, probably because these reptiles are generally assumed to
> be obligate carnivores incapable of digesting vegetable proteins and
> polysaccharides. Herein we review the literature on crocodilian diet,
> foraging ecology, digestive physiology and movement patterns, and
> provide additional empirical data from recent dietary studies of
> Alligator mississippiensis. We found evidence of frugivory in 13 of 18
> (72.2%) species for which dietary information was available,
> indicating this behavior is widespread among the Crocodylia.
> Thirty-four families and 46 genera of plants were consumed by
> crocodilians. Fruit types consumed by crocodilians varied widely; over
> half (52.1%) were fleshy fruits. Some fruits are consumed as
> gastroliths or ingested incidental to prey capture; however, there is
> little doubt that on occasion, fruit is deliberately consumed, often
> in large quantities. Sensory cues involved in crocodilian frugivory
> are poorly understood, although airborne and waterborne cues as well
> as surface disturbances seem important. Crocodilians likely accrue
> nutritional benefits from frugivory and there are no a priori reasons
> to assume otherwise. Ingested seeds are regurgitated, retained in the
> stomach for indefinite and often lengthy periods, or passed through
> the digestive tract and excreted in feces. Chemical and mechanical
> scarification of seeds probably occurs in the stomach, but what
> effects these processes have on seed viability remain unknown. Because
> crocodilians have large territories and undertake lengthy movements,
> seeds are likely transported well beyond the parent plant before being
> voided. Little is known about the ultimate fate of seeds ingested by
> crocodilians; however, deposition sites could prove suitable for seed
> germination. Although there is no evidence for a crocodilian-specific
> dispersal syndrome similar to that described for other reptiles, our
> review strongly suggests that crocodilians function as effective
> agents of seed dispersal. Crocodilian saurochory offers a fertile
> ground for future research.
>
> ==
>
> J. J. Liston & S. D. Chapman (2013)
> Alfred Nicholson Leeds and the first fossil egg attributed to a ‘saurian’.
> Historical Biology (advance online publication)
> DOI:10.1080/08912963.2013.809575
> http://www.tandfonline.com/doi/full/10.1080/08912963.2013.809575#.Ue9Lk421EYE
>
> Discovered by the nineteenth century collector Alfred Nicholson Leeds,
> the first object to be described (1898) as a fossil reptile egg is a
> unique find from the Oxford Clay near Peterborough. It also comes from
> one of a very small number of Jurassic localities worldwide that can
> claim to have yielded a fossil egg. Given its historical and
> contemporary significance, this object is reassessed in the light of
> increased understanding of such objects. Data from scanning electron
> microscopy, computerised tomography, synchrotron imaging, X-ray
> diffraction and petrographic thin sectioning prove inconclusive.
> However, the presence of apparent external openings resembling
> angusticanaliculate pores – a pore type common only to certain types
> of dinosaur eggshell – in both size and sparseness of distribution
> prevents its summary dismissal as not being a dinosaurian egg.
>
> ===
>
> Borja Esteve-Altava, Jesús Marugán-Lobón, Héctor Botella & Diego
> Rasskin-Gutman (2013)
> Random Loss and Selective Fusion of Bones Originate Morphological
> Complexity Trends in Tetrapod Skull Networks.
> Evolutionary Biology (advance online publication)
> DOI: 10.1007/s11692-013-9245-4
> http://link.springer.com/article/10.1007/s11692-013-9245-4
>
>
> The tetrapod skull has undergone a reduction in number of bones in all
> major lineages since the origin of vertebrates, an evolutionary trend
> known as Williston’s Law. Using connectivity relations between bones
> as a proxy for morphological complexity we showed that this reduction
> in number of bones generated an evolutionary trend toward more complex
> skulls. This would imply that connectivity patterns among bones impose
> structural constraints on bone loss and fusion that increase bone
> burden due to the formation of new functional and developmental
> dependencies; thus, the higher the number of connections, the higher
> the burden. Here, we test this hypothesis by exploring plausible
> evolutionary scenarios based on selective versus random processes of
> bone loss and fusion. To do this, we have built a computational model
> that reduces iteratively the number of bones by loss and fusion,
> starting from hypothetical ancestral skulls represented as Gabriel
> networks in which bones are nodes and suture connections are links.
> Simulation results indicate that losses and fusions of bones affect
> skull structure differently whether they target bones at random or
> selectively depending on the number of bone connections. Our findings
> support a mixed scenario for Williston’s Law: the random loss of
> poorly connected bones and the selective fusion of the most connected
> ones. This evolutionary scenario offers a new explanation for the
> increase of morphological complexity in the tetrapod skull by
> reduction of bones during development.
>
> ==