Welcome to the 31st IUBS General Assembly and Conference on ...

never‐ending s<strong>to</strong>ry. Due <strong>to</strong> <strong>the</strong> continuously changing
environment, new issues arise every day, which must be
addressed <strong>to</strong> <strong>the</strong> best of our knowledge.
Locomo<strong>to</strong>r inference of fossil mammals
based on quantitative morphometric
analysis of <strong>the</strong> postcranial skele<strong>to</strong>n of
small­bodied extant taxa
Meng CHEN
Department of Biology, University of Washing<strong>to</strong>n, 456 Kincaid
Hall, Box 351800, Seattle, WA 98195‐1800, USA. Email:
mengchen@uw.edu
simple measurements estimates <strong>the</strong> locomo<strong>to</strong>r
adaptation of fossil mammals more accurately <strong>and</strong>
effectively than previous qualitative methods.
Major macroevolutionary events <strong>and</strong> <strong>the</strong>ir
dynamics between 480 Ma <strong>and</strong> 430 Ma of
Earth his<strong>to</strong>ry: evidences from South China
Renbin ZHAN <strong>and</strong> Jiayu RONG
State Key Labora<strong>to</strong>ry of Palaeobiology <strong>and</strong> Stratigraphy,
Nanjing Institute of Geology <strong>and</strong> Palaeon<strong>to</strong>logy, CAS, Nanjing
210008, China. Email: rbzhan@nigpas.ac.cn;
jyrong@nigpas.ac.cn
Recent studies of fossil mammal skele<strong>to</strong>ns from <strong>the</strong> Jehol
Group of western Liaoning, China have revealed a much
greater diversity of locomo<strong>to</strong>r adaptations of Mesozoic
mammals than previously known. Instead of <strong>the</strong>
traditional perception that Mesozoic mammals were
generalized terrestrial animals, <strong>the</strong>se discoveries indicate
that mammals of <strong>the</strong> Jehol Group probably approached
<strong>the</strong> ecological diversity of extant mammals. To develop a
method <strong>to</strong> quantify <strong>the</strong> range of locomo<strong>to</strong>r morphotypes
among Mesozoic mammals, I conducted a morphometric
analysis of <strong>the</strong> entire postcranial skele<strong>to</strong>n of 51
small‐bodied extant mammals of 13 orders. Eight
locomo<strong>to</strong>r categories were used <strong>and</strong> 24 osteological
indices were derived from 54 linear measurements of <strong>the</strong>
entire postcranial skele<strong>to</strong>n in contrast <strong>to</strong> <strong>the</strong> indices of
individual elements applied in previous studies. Linear
Discriminant Analysis of those indices indicates
statistically significant differences among <strong>the</strong> diverse
locomo<strong>to</strong>r categories. In <strong>the</strong> Linear Discriminant Analysis
plots, fossorial <strong>and</strong> salta<strong>to</strong>rial mammals have particularly
distinctive postcranial skele<strong>to</strong>ns for specialized locomo<strong>to</strong>r
adaptations, whereas arboreal, scansorial, <strong>and</strong> terrestrial
mammals show some overlap suggesting that similar
morphological features may respond <strong>to</strong> different
locomo<strong>to</strong>r adaptations. Two fossil representatives,
Yanoconodon <strong>and</strong> Fruitafossor, are shown by Principle
Component Analysis <strong>to</strong> plot among generalized terrestrial
<strong>and</strong> specialized fossorial mammals, respectively. This
preliminary study suggests that this quantitative
morphometric analysis helps identify <strong>the</strong> critical indices
derived from <strong>the</strong> entire postcranial skele<strong>to</strong>n for
distinguishing locomo<strong>to</strong>r categories <strong>and</strong> with just several
The time interval between 480 Ma <strong>and</strong> 430 Ma of Earth
his<strong>to</strong>ry includes <strong>the</strong> Ordovician Period <strong>and</strong> <strong>the</strong> early
Silurian Period (<strong>the</strong> Ll<strong>and</strong>overy Epoch), during which
<strong>the</strong> Earth ecosystem experienced 2 major
macroevolutionary events, i.e. <strong>the</strong> Great Ordovician
Biodiversification Event (GOBE) <strong>and</strong> <strong>the</strong> end‐Ordovician
mass extinction.
The GOBE was <strong>the</strong> first radiation of <strong>the</strong> Paleozoic
Evolutionary Fauna (PEF). It lasted for tens of millions
years when several diversity acmes occurred <strong>and</strong> <strong>the</strong>
basic framework of <strong>the</strong> PEF was established <strong>and</strong>
stabilized. It was manifested not only by a rapid
increase of <strong>the</strong> α‐diversity (<strong>the</strong> number of taxa) of
marine organisms, but also by a substantial expansion
of marine ecosystem, i.e. an increase of β‐diversity (<strong>the</strong>
number of communities) <strong>and</strong> an expansion of ecological
niches. After <strong>the</strong> GOBE, different niches, from near
shore shallow water <strong>to</strong> off shore deeper water, from <strong>the</strong>
water surface through different depths of <strong>the</strong> water
column <strong>to</strong> <strong>the</strong> sea floor <strong>and</strong> even within <strong>the</strong> soft
substrate, were all occupied by different organisms of
different ecotypes. The GOBE was also characterized by
strong heterochroneity between different organisms
within <strong>the</strong> same paleoplate, between different major
groups of <strong>the</strong> same phylum of organism, between
different paleogeographic settings within a single block
(from platform through slope <strong>to</strong> basin), between
different blocks, etc. It is now commonly accepted that
<strong>the</strong> GOBE happened without sudden environmental
changes of ei<strong>the</strong>r regional or global scales. Also, it is
thought <strong>to</strong> be controlled by both intrinsic <strong>and</strong> extrinsic
fac<strong>to</strong>rs, but still controversial on <strong>the</strong> leading fac<strong>to</strong>r(s).
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