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

Drosophila <strong>and</strong> crustacean Arthropods. We are working
on <strong>the</strong> evolution of diversity in number, size <strong>and</strong> shape in
insect wings by investigating <strong>the</strong> nature of wing
patterning genes that are regulated by Ubx in different
insect species such as Apis, butterflies, silkworm,
Tribolium, mosqui<strong>to</strong> <strong>and</strong> different species of Drosophila.
Mammalian evolution as reflected by key
transitional features in brain <strong>and</strong> ear: new
evidence from Mesozoic mammals of China
Meng JIN
American Museum of Natural His<strong>to</strong>ry, New York, USA. Email:
jmeng@amnh.org
The crown Mammalia can be defined phylogenetically as
<strong>the</strong> clade consisting of <strong>the</strong> most recent common ances<strong>to</strong>r
of extant monotremes <strong>and</strong> placentals <strong>and</strong> all descendants
of that ances<strong>to</strong>r. This clade can be diagnosed by many
characters, such as <strong>the</strong> enlarged brain, complex bony
nasal turbinals associated with <strong>the</strong> development of <strong>the</strong>
secondary palate, <strong>the</strong> dentary‐squamosal jaw joint, <strong>and</strong>
<strong>the</strong> tri‐ossicle middle ears. These features are important
<strong>and</strong> critical for various aspects of mammalian biology,
including endo<strong>the</strong>rm, sense of smell, hearing <strong>and</strong>
mastication. Studies of mammalian evolution have
traditionally focused on <strong>the</strong>se ana<strong>to</strong>mic regions in
exploring how <strong>the</strong> mammalian conditions were evolved
from <strong>the</strong>ir <strong>the</strong>rapsid ances<strong>to</strong>rs. Because of <strong>the</strong> rareness
of good fossils in early mammals, many issues relating <strong>to</strong>
<strong>the</strong>se features remain open. For instance, early works on
brain evolution largely focused on <strong>the</strong> overall size <strong>and</strong>
sizes of major brain parts, but more detailed morphology
<strong>and</strong> <strong>the</strong> relationships of <strong>the</strong> brain development with o<strong>the</strong>r
parts of <strong>the</strong> skull (nasal structures, eyes <strong>and</strong> ears) are
relatively little known. Even for <strong>the</strong> middle ear evolution,
perhaps <strong>the</strong> most intensively studied region in
mammalian evolution, <strong>the</strong> detail morphologies of those
small ossicles are until recently not known.
During <strong>the</strong> last 2 decades, several Mesozoic mammals
represented by well‐preserved material have been
discovered from China, such as Zhangheo<strong>the</strong>rium,
Mao<strong>the</strong>rium, Repenomamus, Gobiconodon, Cas<strong>to</strong>rocauda,
Volantico<strong>the</strong>rium, Yanoconodon, <strong>and</strong> Liaoconodon. These
fossils provide a great deal of morphological information
that casts new light on <strong>the</strong> evolution of mammals. Along
with discoveries from o<strong>the</strong>r regions, <strong>the</strong>y demonstrate
an early radiation of life styles in Mesozoic mammals
<strong>and</strong>, more importantly <strong>and</strong> for <strong>the</strong> first time ever,
provide <strong>the</strong> detail morphologies of <strong>the</strong> ec<strong>to</strong>tympanic
(angular), malleus (articular <strong>and</strong> prearticular), <strong>and</strong> incus
(quadrate) of Early Cretaceous eutriconodontan
mammals. Using <strong>the</strong> X‐ray computed <strong>to</strong>mography we
can reconstruct internal structures of <strong>the</strong> nasal <strong>and</strong>
brain cavities, <strong>the</strong> inner ear <strong>and</strong> dental eruptions from
Mesozoic mammal skulls that are in 3D preservation.
With <strong>the</strong>se new morphological data, coupled with those
from recent developmental <strong>and</strong> molecular studies on
extant mammals, we are able <strong>to</strong> recognize a transitional
stage during <strong>the</strong> evolution of mammalian middle ear <strong>and</strong>
throw light on <strong>the</strong> possible relationship between <strong>the</strong>
expansion of <strong>the</strong> mammalian brain <strong>and</strong> development of
mammalian sensory organs as reflected by <strong>the</strong>
morphologies of <strong>the</strong> nasal cavities, braincase, eye
sockets, inner ear <strong>and</strong> o<strong>the</strong>r regions of <strong>the</strong> skull.
Mammal traits <strong>and</strong> environment: molar
<strong>to</strong>oth crown height <strong>and</strong> precipitation
Eronen JUSSI
Department of Geosciences <strong>and</strong> Geography, University of
Helsinki, PO Box 64, Helsinki FIN‐00014, Finl<strong>and</strong>. Email:
jussi.t.eronen@helsinki.fi
The climate system can be investigated from different
perspectives. For <strong>the</strong> study of past climate systems
modeling offers wide variety of <strong>to</strong>ols. But <strong>to</strong> validate <strong>and</strong>
compare <strong>the</strong> results from modeling, we need large
datasets that span both temporal <strong>and</strong> spatial
dimensions with relatively dense sampling. With <strong>the</strong>
recent breakthroughs in developing proxies for
environmental conditions, we can now use mammal
data <strong>to</strong> create estimates of rainfall at different scales in
<strong>the</strong> past. The fossil mammals offer <strong>the</strong> most spatially
<strong>and</strong> temporally resolved record for terrestrial
environments of <strong>the</strong> Cenozoic (65 Ma <strong>to</strong> 1.8 Ma). One of
data‐sources for <strong>the</strong>se data is <strong>the</strong> open access
NOW‐database (http://www.helsinki.fi/science/now/)
that contains information about Eurasian l<strong>and</strong> mammal
taxa <strong>and</strong> localities. We can resolve <strong>the</strong> spatial variability
of <strong>the</strong> past climates at regional <strong>and</strong> continental scale,
<strong>and</strong> track <strong>the</strong> variability at different temporal scales. For
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