[Taxacom] Mesozoic origins of many insect families (was: ISE...)

[Kenneth Kinman]

Hi Vladimir,
       Thanks for the statistics.  The presently known Dipteran families

(modern) that are pre-Cretaceous are therefore 26, and add to that those

which are only known from the Cenozoic (post-Cretaceous) would yield a
total close to (or even exceeding) the 36 families originating in the
Cretaceous.  That is certainly what I would have expected.  Definitely
no "vast majority" originating in the Cretaceous.      
      As for 25 families going extinct in the Jurassic (which seems too
high), I suspect that this is due to two factors: (1) some of them made
it into the Cretaceous, but haven't yet been documented in the
Cretaceous; and (2) some of those Jurassic families are actually
paraphyletic with respect to extant families that are presently viewed
as first appearing in the Cretaceous (thus being pseudoextinctions
vis-a-vis the Jurassic-Cretaceous boundary).      
     Therefore (thirdly), I would be suspicious that these numbers
actually indicate the faunal turnover of insect families during the
Jurassic-Cretaceous transition to be quite that significant, compared to

the Permian-Triassic extinction, the Cretaceous-Cenozoic (K-T)
extinction, or even the Triassic-Jurassic extinction.  My experience is
that the Jurassic-Cretaceous transition was probably milder than any of
those other three, and that a lot of taxa crossed that boundary even
though pseudoextinction and a poor Jurassic fossil record has made that
transition appear more abrupt than it actually was.  It certainly cannot

rival the devastation of either the Permo-Triassic or end-Cretaceous
extinctions.    
            -----Cheers,
                        Ken Kinman            
----------------------------------------------------
     
Vladimir Blagoderov wrote:         
     If you take Diptera, number of recent families known from
Mesozioc periods:  

Triassic: 2 
Jurassic: 24 
Cretaceous: 36 

On the other hand, number of groups considered to be of family rank last

known from the periods:  

Triassic: 5 
Jurassic: 25 
Cretaceous: 12  

By mid Cretaceous Diptera fauna consists almost entirely of recent
families; the same is true for most of other insect orders. So there is
a huge faunal turnover in Late Jurassic-early Cretaceous. 
Cheers, 
Vlad 
-- 
Dr Vladimir Blagoderov, FLS 
Department of Entomology 
The Natural History Museum 
Cromwell Road, London 
SW7 5BD, UK