New research shows how geology
drove the diversification and spread of songbirds, the world’s most abundant
bird group
Wednesday 19 October 2016
11.53 BST Last modified on Wednesday 19 October 2016 18.27 BST
Today, songbirds are the most
successful group of birds on the planet. With more than 5000 species worldwide,
they form half of the world’s known bird species, and have colonised almost all
corners of the world (with the exception of Antarctica).
Songbirds, or Passeriformes, are
often referred to as “perching birds”, which refers to the arrangement of their
toes - with three toes pointing forward and one pointing backwards - which
allows them to comfortably cling to trees and branches. But to the outside
world, they are best known for their well-developed vocalisations. Who hasn’t
delighted in waking up in the middle of a summer night by birds
enthusiastically welcoming the new day?
Zoologists divide
modern songbirds in three groups. Oscines (Passeri)
constitute over 4000 species and can be found all over the world. Suboscines (Tyranni) are
mostly found in the Neotropics, whereas the small New Zealand wrens (Acanthisitti) are
limited to, you guessed it, New Zealand.
As abundant and widespread as
songbirds are today, their fossil record is meager, especially the further we
go back in time. The earliest known songbird as we know them comes from the
early Eocene
(approximately 54 million years ago) Tingamarra fauna
from Murgon in southeastern Queensland, Australia (Boles, 1997). The specimen
consists of only two bones, a carpometacarpus and a tibiotarsus, but exhibits
anatomical features that are also found within modern day songbirds. But how
did this group rise from the isolated Australian continent to worldwide
domination?
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