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Re: Island-dwelling dinosaurs (was Re: Gargantuavis neck vertebra)



Interesting idea. Secretarybirds and ground hornbills might be good models here.

Well, they're all not flightless, and at least secretarybirds and seriemas still roost in trees a lot, IIRC even nest there. No time to look up the hornbills.

However, truncatedly:

Am 18.06.2012 um 17:53 schrieb Brian Lauret:

It's also noteworthy that the Tasmanian Native Hen is a flightless coot. It=
's not overly large and would have evolved alongside thylacines=2C dasyurid=
s and thylacoleonids for starters.  Even today=2C the species survives amon=
g foxes and cats. The New Guinea Flightless Rail is another example. Though=
  this large flightless species appears to spend a lot of its life in trees=
=2C it does ascend to the ground and would have evolved among the same set =
of predators as did the Native Hen. In the Pleistocene=2C Australia also ha=
d a flightless megapode of non-gigantic size.
Clearly=2C these are birds that like *Patagopteryx* appear to prove both th=
e 'small flightless birds only evolve on islands'-rule and 'continental fli=
ghtless birds need to be big to survive'-rule wrong. Likewise=2C tapaculos =
have also been considered flightless.

Besides various ratites=2C the gastornithids=2C brontornithids=2C *Eremopez=
us* and the phorusrhacids the Paleogene offered a variety of smaller flight=
less or nearly flightless birds such as ameghinornithids=2C sophiornithids=
=2C bathornithids and idiornithids. *Salmilia* and eogruids were also fligh=
tless though the latter grew fairly large. All of these are Laurasian=2C so=
  who knows what lived in Gondwana at the time. *Lavocatavis* is thought to =
be an African phorusrhacid=2C but given biogeographic reasons it too might =
have evolved flightlessness independently.  Lastly=2C *Euroceros* might be =
worth a mention given that it appears to have been a large ground hornbill =
of diminished flight ability=2C that lived in Pliocene Europe...not a place=
  and location without potential mammalian predators.

What we consider to be normal weaknesses and behaviour for flightless birds=
  on islands may not be particularly applicable to flightless birds that evo=
lve on continents=2C rarer though they may be.

Brian

That's a lot of animals I'll have to inform myself about. ...in 3 weeks at the earliest.