Modern forms
The multituberculate order has no modern forms;
it survived
only until the end of the Eocene, mid-Tertiary.
Their Extinction
The multituberculates started to decline
suddenly at the
beginning of the Tertiary. The
reasons for their decline and extinction are unknown, but it could be
that multituberculates were outcompeted by placental
mammal
groups, especially early primates and rodents. The placental mammals
were diversifying in the Tertiary, so the decline, at the same time, of
the multituberculates would suggest that the placental mammals had some
kind of
competitive edge over multituberculates.
In placental mammals, the young do most of their development in the
womb, which means that when they are born they are less dependent on
the mother. It would seem that multituberculate young were very small
and little developed at birth, much like marsupials, where most of the
development of the young is in the pouch after birth (see
Reproduction).
The strategy of
placental mammals is generally thought to be superior and to have been
at the origin of their diversification success. The
multituberculate strategy may have been one of the factors which made
them competitively inferior to placental mammals.
It has also been suggested that the sprawling posture
of
multituberculate limbs limited their endurance for
long-term running, another disadvantage compared to placental mammals
with an upright posture.
The similarities between rodents and multituberculates, notably in the
teeth and skull anatomy, could indicate similar diet so competition for
food , but as yet the fossil record of multituberculates and
early rodents only allows us to guess at what use each made of the
resources in their environment. There is no way of conclusively proving
that multituberculates and rodents were in direct competition,
exploiting the same environment at the same time, although both groups
have been reconstructed as small nocturnal granivores (eating seeds and
nuts).
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Subgroups | Fossil
Record | Modern Forms
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and web links
Author: Aude Caromel
Last updated: 20/11/06
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produced by students
on the MSc
Palaeobiology programme in the Department
of Earth Sciences at the University of Bristol for academic
year 2006-7
