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Palynology of the Triassic upper Chinle Formation in northern New Mexico + more

Ben Creisler

Some recent non-dino items:

Rivista italiana di Paleontologia e Stratigrafia

Now in open access through current issues 2015


Sofie Lindström, Randall B. Irmis, Jessica H. Whiteside, Nathan D.
Smith, Sterling J. Nesbitt & Alan H. Turner (2015)
Palynology of the upper Chinle Formation in northern New Mexico,
U.S.A.: Implications for biostratigraphy and terrestrial ecosystem
change during the Late Triassic (Norian–Rhaetian).
Review of Palaeobotany and Palynology (advance online publication)


New palynological data from the upper part of the Upper Triassic
Chinle Formation
Late Norian-Rhaetian age from palynostratigraphy and detrital zircon U-Pb age
Evidence of major ongoing ecosystem change and restructuring of flora
May help explain lack of herbivorous vertebrates in the Chinle fauna
Global Late Triassic ecosystem change expressed differently on a regional scale


A new densely sampled palynological record from the vertebrate-bearing
upper Chinle Formation at Ghost Ranch in the Chama Basin of
northwestern New Mexico provides insights into the biostratigraphy and
terrestrial ecosystem changes during the Late Triassic of northwestern
Pangaea. Spore-pollen assemblages from the Poleo Sandstone, Petrified
Forest, and 'siltstone' members are dominated by pollen of
corystospermous seed ferns (Alisporites) and voltziacean conifers
(Enzonalasporites, Patinasporites). Other abundant taxa include
Klausipollenites gouldii and the enigmatic fused tetrad
Froelichsporites traversei, whereas spores of ferns and fern allies
are generally rare. The assemblages are correlated with Zone III
Chinle palynofloras of previous authors. The lower assemblages contain
rare occurrences of typical Zone II taxa, namely Cycadopites stonei,
Equisetosporites chinleanus and Lagenella martini, that may either be
reworked or represent relictual floral elements. Marked step-wise
losses of species richness, along with only minor appearances of new
taxa, led to a total 50% drop in range-through diversity during the
late Norian of the Chama Basin. Correlations with other Chinle records
in the western U.S. reveal differences in the stratigraphic ranges of
some spore-pollen taxa, likely attributable to local/regional
differences in environmental conditions, such as groundwater
availability, precipitation, nutrients, and temperature, rather than
stratigraphic miscorrelation. This is interpreted as a consequence of
environmental stress resulting from increased aridity coincident with
the northward movement of Pangaea. Similarly, major differences
between the western and eastern U.S. and northwest Europe can be
attributed to floral provincialism governed by climatic zones during
the Late Triassic.


Mauricio A. Fuentes (2015)
Theoretical considerations on maximum running speeds for large and
small animals.
Journal of Theoretical Biology (advance online publication)


Equations for top running speeds are listed, derived, and discussed.
A model for the speed limitation of large animals is developed.
There are different scaling trends for top speeds of large versus small animals.
The scaling for large animals appears to be: Speed ~(Body Mass)−0.15.


Mechanical equations for fast running speeds are presented and
analyzed. One of the equations and its associated model predict that
animals tend to experience larger mechanical stresses in their limbs
(muscles, tendons and bones) as a result of larger stride lengths,
suggesting a structural restriction entailing the existence of an
absolute maximum possible stride length. The consequence for big
animals is that an increasingly larger body mass implies decreasing
maximal speeds, given that the stride frequency generally decreases
for increasingly larger animals. Another restriction, acting on small
animals, is discussed only in preliminary terms, but it seems safe to
assume from previous studies that for a given range of body masses of
small animals, those which are bigger are faster. The difference
between speed scaling trends for large and small animals implies the
existence of a range of intermediate body masses corresponding to the
fastest animals.