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Mesozoic parasites (was Re: GSA talks about dinosaur-related stuff)



> MESOZOIC PARASITES FROM CHINA
> HUANG, Diying, Nanjing Institute of Geology and Palaeontology, CAS,
> No. 39 East Beijing Road, Nanjing 210008 China, huangdiying@sina.com
> Newly discovered Mesozoic fleas have been recently reported from the
> Middle Jurassic Daohugou fauna (ca. 165 Ma) and the Early Cretaceous
> Jehol fauna (ca. 125 Ma) of Northeast China. These giant fleas are
> represented by three forms each with both with males and females. The
> females are slightly to distinctly larger than the males. These
> ancient ectoparasites display some general habitus, such as large size
> (more than 2 cm long in some specimens), more or less dorso-ventrally
> flattened body, and non-jumping hind legs. Their developed,
> posteriorly-directed setae on thorax and abdomen and scattered
> ctenidia on legs indicate an ectoparasitical behavior that lived on
> haired or feathered vertebrates. Most modern fleas parasitize mammals,
> and small, advanced groups (about 5%) parasitize birds. The possible
> Mesozoic hosts of these fossil fleas include dinosaurs and pterosaurs
> with hair-like feathers, early birds, and early mammals. [snip]


Aside from how innately fascinating (and cool) these parasites are,
they also make me wonder what was eating them.  A 2 cm proto-flea
would be a tasty morsel for a pterosaur or a small theropod.
Pterosaurs could alight on a large dinosaurian host from above; but
non-avian theropods presumably had to climb up.  Did microraptorines
and scansoriopterygids clamber up the feathery hides of much larger
dinosaurs to pick at arthropod parasites - and then glide back down to
the ground?  It offers an explanation for "trees-down" aerial behavior
by small theropods, without the need for trees.


Jaime has already interpreted scansoriopterygids as "nit-pickers"
based on their dental morphology:

http://qilong.wordpress.com/2011/08/23/incredulous-teeth-iii-the-nitpicker/


> Strashila is the most bizarre animal among all known fossil insects.
> It was hypothesized to be an ectoparasite, even a supposed dinosaur
> parasite. The new morphological details indicate it is a true aquatic
> insect.


In the original description of _Strashila_, Rasnitsyn (1992) raised
the possibility that its lateral abdominal outgrowths indicated
aquatic habits - but Rasnitsyn subsequently rejected an aquatic
interpretation based on the apparent lack of any other possible
aquatic adaptations.  So this re-interpretation of _Strashila_ as
aquatic will be very interesting.


> Moreover, Saurodectes vrsanskyi from Siberia was suggested to
> have louse affinities, but it is more likely a wingless dipteran.


So _Saurodectes_ was possibly still ectoparasitic, like the keds
(louse flies) in today's world.





Cheers

Tim