Subterranean lizards would logically rank very high on the scale of
vertebrate raftability, I would think -- extended survival in a large
rotting log seems almost a given.
Although I never thought about it much before reading the
IIRC, debris from Japan only took a couple months to get to NA
*From: * Dan Chure <firstname.lastname@example.org>;
*To: * <email@example.com>; <firstname.lastname@example.org>;
*Subject: * Re: Bird bones cells surface area + next-generation
paleornithology + worm lizards and end-Cretaceous mass extinction
*Sent: * Fri, Apr 3, 2015 2:19:05 PM
Relative to the amphisbaenian paper mentioned below, out of curiosity
how extensive are the modern observations of vertebrate rafting across
oceans? I know rafting has been seen but there is a difference between
finding an African vertebrate on a raft 200 km out into the Atlantic and
a raft with an African verebrate 200 km off the coast of South America.
Certainly small vertebrates would seem to be more prone to successful
dispersal via rafting than larger ones. Continental drift still plays
into the rafting scenarios in that it can eventually move land masses so
far apart that the distance, which via ocean currents may not be the
shortest direct path, makes successful rafting effectively impossible.
On 4/2/2015 5:25 PM, Ben Creisler wrote:
> Ben Creisler
> A number of recent non-dino papers that may be of interest:
> John M. Rensberger , Ricardo N. Martínez
> Bone Cells in Birds Show Exceptional Surface Area, a Characteristic
> Tracing Back to Saurischian Dinosaurs of the Late Triassic.
> PLoS ONE 10(4): e0119083.
> Dinosaurs are unique among terrestrial tetrapods in their body sizes,
> which range from less than 3 gm in hummingbirds to 70,000 kg or more
> in sauropods. Studies of the microstructure of bone tissue have
> indicated that large dinosaurs, once believed to be slow growing,
> attained maturity at rates comparable to or greater than those of
> large mammals. A number of structural criteria in bone tissue have
> been used to assess differences in rates of osteogenesis in extinct
> taxa, including counts of lines of arrested growth and the density of
> vascular canals.
> Methodology/Principal Findings
> Here, we examine the density of the cytoplasmic surface of
> bone-producing cells, a feature which may set an upper limit to the
> rate of osteogenesis. Osteocyte lacunae and canaliculi, the cavities
> in bone containing osteocytes and their extensions, were measured in
> thin-sections of primary (woven and parallel fibered) bone in a
> diversity of tetrapods. The results indicate that bone cell surfaces
> are more densely organized in the Saurischia (extant birds, extinct
> Mesozoic Theropoda and Sauropodomorpha) than in other tetrapods, a
> result of denser branching of the cell extensions. The highest
> postnatal growth rates among extant tetrapods occur in modern birds,
> the only surviving saurischians, and the finding of exceptional
> cytoplasmic surface area of the cells that produce bone in this group
> suggests a relationship with bone growth rate. In support of this
> relationship is finding the lowest cell surface density among the
> saurischians examined in Dinornis, a member of a group of ratites that
> evolved in New Zealand in isolation from mammalian predators and show
> other evidence of lowered maturation rates.
> Jamie R. Wood and Vanesa L. De Pietri (2015)
> Next-generation paleornithology: Technological and methodological
> advances allow new insights into the evolutionary and ecological
> histories of living birds.
> The Auk 132(2):486-506
> doi: http://dx.doi.org/10.1642/AUK-14-257.1
> Paleornithology, the study of fossil or ancient bird remains, provides
> an important context for understanding the biology, evolutionary
> history, and ecology of living birds. Recent technological and
> methodological advances in the field of paleornithology have opened up
> the potential to extract new pools of information from fossil bird
> remains, and hence provide new insights into the histories of living
> birds. Here we review some of these advances, covering aspects of
> ancient DNA and protein analyses, sedimentary proxies for birds,
> stable isotope analyses, coprolite analyses, high-resolution computed
> tomography, paleoneurology, finite elements analysis, and
> paleohistology. These new advances offer exciting prospects for the
> future of paleornithology, but also reaffirm the importance of basic
> fieldwork, exploration and the discovery of new fossil specimens,
> museum archives in which to curate the specimens, and traditional
> morphological approaches to studying the fossil remains.
> Nicholas R. Longrich, Jakob Vinther, R. Alexander Pyron, Davide Pisani
> & Jacques A. Gauthier (2015)
> Biogeography of worm lizards (Amphisbaenia) driven by end-Cretaceous
> mass extinction.
> Proceedings of the Royal Society B: 2015 282 20143034
> DOI: 10.1098/rspb.2014.3034.
> Worm lizards (Amphisbaenia) are burrowing squamates that live as
> subterranean predators. Their underground existence should limit
> dispersal, yet they are widespread throughout the Americas, Europe and
> Africa. This pattern was traditionally explained by continental drift,
> but molecular clocks suggest a Cenozoic diversification, long after
> the break-up of Pangaea, implying dispersal. Here, we describe
> primitive amphisbaenians from the North American Palaeocene, including
> the oldest known amphisbaenian, and provide new and older molecular
> divergence estimates for the clade, showing that worm lizards
> originated in North America, then radiated and dispersed in the
> Palaeogene following the Cretaceous-Palaeogene (K-Pg) extinction. This
> scenario implies at least three trans-oceanic dispersals: from North
> America to Europe, from North America to Africa and from Africa to
> South America. Amphisbaenians provide a striking case study in
> biogeography, suggesting that the role of continental drift in
> biogeography may be overstated. Instead, these patterns support Darwin
> and Wallace's hypothesis that the geographical ranges of modern clades
> result from dispersal, including oceanic rafting. Mass extinctions may
> facilitate dispersal events by eliminating competitors and predators
> that would otherwise hinder establishment of dispersing populations,
> removing biotic barriers to dispersal.
> End-Triassic Extinction
> Sofie Lindström, Gunver Krarup Pedersen, Bas van de Schootbrugge,
> Katrine Hovedskov Hansen, Natascha Kuhlmann, Jean Thein, Leif
> Johansson, Henrik Ingermann Petersen, Carl Alwmark, Karen Dybkjær,
> Rikke Weibel, Mikael Erlström, Lars Henrik Nielsen, Wolfgang Oschmann,
> and Christian Tegner (2015)
> Intense and widespread seismicity during the end-Triassic mass
> extinction due to emplacement of a large igneous province.
> Geology (advance online publication)
> Multiple levels of earthquake-induced soft-sediment deformations
> (seismites) are concentrated in the end-Triassic mass extinction
> interval across Europe. The repetitive nature of the seismites rules
> out an origin by an extraterrestrial impact. Instead, this intense
> seismic activity is linked to the formation of the Central Atlantic
> magmatic province (CAMP). By the earliest Jurassic the seismic
> activity had ceased, while extrusive volcanism still continued and
> biotic recovery was on its way. This suggests that magmatic intrusions
> into sedimentary strata during early stages of CAMP formation caused
> emission of gases (SO2, halocarbons, polycyclic aromatic hydrocarbons)
> that may have played a major part in the biotic crisis.
> Alex H. Kasprak, Julio Sepúlveda, Rosalyn Price-Waldman, Kenneth H.
> Williford, Shane D. Schoepfer, James W. Haggart, Peter D. Ward, Roger
> E. Summons, and Jessica H. Whiteside (2015)
> Episodic photic zone euxinia in the northeastern Panthalassic Ocean
> during the end-Triassic extinction.
> Geology 43:. 307-310
> Severe changes in ocean redox, nutrient cycling, and marine
> productivity accompanied most Phanerozoic mass extinctions. However,
> evidence for marine photic zone euxinia (PZE) as a globally important
> extinction mechanism for the end-Triassic extinction (ETE) is
> currently lacking. Fossil molecular (biomarker) and nitrogen isotopic
> records from a sedimentary sequence in western Canada provide the
> first conclusive evidence of PZE and disrupted biogeochemistry in
> neritic waters of the Panthalassic Ocean during the end Triassic.
> Increasing water-column stratification and deoxygenation across the
> ETE led to PZE in the Early Jurassic, paralleled by a perturbed
> nitrogen cycle and ecological turnovers among noncalcifying groups,
> including eukaryotic algae and prokaryotic plankton. If such
> conditions developed widely in the Panthalassic Ocean, PZE might have
> been a potent mechanism for the ETE.