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Morphological dating

In analogy to molecular dating, the following SVP meeting abstract presents the idea of using morphological data for deriving divergence date estimates.

My thesis supervisor had the same idea; we'll put it into my thesis, but we won't be able to sell it as new anymore.

And in case anyone wonders, I'm a touch-typist :o)


Thomas DeCecchi & Hans Larsson: Tempos and modes of theropod evolution, p. 67A

Genomic clocks, a method [sic] for dating lineage divergences through the steady regular accumulations of sequence mutations, has become a standard tool in evolutionary biology[,] yet is of limited use in paleontology. Genomic information is generally absent in fossils but a large amount of data is preserved in skeletal morphology. We present a novel method that estimate[s] a "morphological clock" to examine divergence times within Theropoda. Origination times for major clades of theropods are calculated using a recent large and broad-ranging data set from [the book] "The Dinosauria" and grounded with known geological times for specimens. This method has also been extended to predict the origin of theropods and can, when combined with traditional "relative" rate measurements, allow for comparisons between different evolutionary trajectories within Theropoda. The results presented give the first insight into absolute evolutionary rates within theropod evolution. They provide data for the evaluation of modular evolutionary rates across the skeleton and transformational evolutionary modes across the lineage. Using this method we have determined the origin of Theropoda at during the Late [sic] Anisian, 5 -- 7 million years before the [Carnian] Ischigualasto fauna, a date consistent with other estimates of theropod origins. Our data shows that at Eumaniraptora (Deinonychosaurians + Aves) there is a noted increase in the rate of character evolution coincident with the origin of flight, especially in the pectoral region. Beginning at the node Eumaniraptora a separate morphological clock using a different calibration points [sic] is proposed to estimate early avian divergence times, since this increase in character rate evolution during this transition is not adequately modeled by the general theropod trend.