EARLY TERTIARY ARBOREAL DINOSAURS

["Darren Naish" <dwn194@soton.ac.uk>]

Nick Longrich (I think) wrote..

> In fact, it does not support the idea that songbirds 
> were around back then- there are many other small birds filling many
> songbird-like roles but they are paleognaths and other weird things. 

Nick is correct in saying that non-passerines played the role of small tree bird
back in the early Tertiary, but he is wrong in saying that 'they [were]
paleognaths..'. Other clades in the land bird assemblage, the coraciiformes and
piciformes, were filling out roles now occupied by passerines back then. The
great palaeornithologist C.J. Harrison wrote about this, and had a paper in
_Nature_ on it. Coraciiformes were also playing at being birds of prey until
true raptors appeared in the late Eocene.

The very earliest known passerines debut in late Eocene deposits Downunder,
reported by Boles I think (in _Nature_). This is in wonderful correlation with
the theory that passerines appeared, diversified and spread from Australia.
They'd got around by mid Oligocene times, as passerines bones are reported from
French rocks if this age at least.

> What I have heard about the late Cretaceous/Eocene fossil record sounds
> like it could be consistent with Feduccia's hypothesis of an avian
> mass-extinction and subsequent re-radiation.

Feduccia's hypothesis is a blatant misrepresentation of data. He argues that
enantiornithines were thriving at wide diversity right up to the KT boundary
(his time chart in the _Science_ article showed this clearly). In reality, this
clade apparently reached its acme somewhat earlier and was becoming rare and
low-diversity by the late Maastrichtian. I don't think any enantiornithine is
known from the end of the Maastrichtian (can someone please check that
assertion?). 

Feduccia also argues that extant bird clades are post-Oligocene novelties.
Mesozoic palaeontologists have been quoted in recent months as saying that there
are actually many Cretaceous fossils of extant clades. I don't have _The Fossil
Record 2_ to hand (Unwin's chapter on the birds would be the best reference to
have for this), but I'm not sure how much faith to put in this. There's
_Presbyornis_, apparently a basal member of the anseriforms, and _Colymboides_,
a supposed Cretaceous gaviiform (diver). But I don't know of any others off the
top of my head (and I emphasise, I do all this off the top of my head..).

However, don't worry about it. Even if there aren't so many Cretaceous examples
of extant clades, what about the early Tertiary? Feduccia wants ratites to be
of very recent origin. He argues that the fact that the Hawaiian turtle-jaw
geese (_Thamnatochen_) evolved a ratite-like morphology within only a few Ma
shows that the ratite morphology needs not be relictual. OK, that's fine - but
what about the Palaeocene ratite from South America? I forget its name. Then
there's Grube Messel - a mid Eocene deposit absolutely stuffed full of extant
kinds of birds. There's a stilt-flamingo intermediate (_Juncitarsus_), an
assemblage of rollers (coraciids), early nightjars and a group of rail relatives
called the messelornithids.

A possible early penguin from New Zealand is late Palaeocene in age, and there
are many Eocene penguins without any doubt. An Antarctic phorushacoid is Eocene
in age, and members of the diatrymid-galliform-anseriform assemblage (probably
the out-group to all later neognaths) were clearly in evidence at this time. The
earliest falconids, parrots, owls and passerines are also known by late Eocene
times. So... birds were really going places in the early Tertiary, and
representatives of very diverse groups - indeed, just about all groups
represented by living species - are in evidence. There was clearly a very
_early_ radiation of extant bird clades, contrary to what Feduccia may want.

Recent results from DNA studies, indicating a late Cretaceous diversification
of birds with big survival into the Tertiary, are in full agreement with the
pattern of radiation indicated by the fossils. I don't see Feduccia's insistence
that extant bird clades are recently evolved as reasonable.

But then, I haven't read his new book, so I'm uncertain as to his exact
arguments nowadays. If you know Feduccia's email address, I strictly forbid you
from fwding this message to him. I have enough enemies for the time being
thanks.

"Are you a god?"
Holtz nods.
"No"
"Then - - die!!"

"Nimble little minx isn't she?"

DARREN NAISH