BASAL AMNIOTA STRUCTURE AND PHYLOGENY WEEK 9 PROCOLOPHONIDAE and RELATIVES S S SUMIDA Procolophonids have been variously placed difficult to define and not surprisingly considered as a potential ancestors to turtles As a group they appear to hang together by virtue ID: 437321
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BIOLOGY 622 – FALL 2014BASAL AMNIOTA - STRUCTURE AND PHYLOGENY WEEK – 9PROCOLOPHONIDAE and RELATIVES S. S. SUMIDASlide2Slide3
Procolophonids have been variously placed, difficult to define, and not surprisingly considered as a potential ancestors to turtles. As a group they appear to hang together by virtue of the broadly flared shape of their cheeks. Recall that this is the first group we examine this term that survived the end-Permian extinction, persisting until the end of the Triassic. However, complicating this is the position of the tetrapod
Owenetta
, a taxon sometimes included in the group, and sometimes considered as its sister-taxon. Cisneros worked on the phylogeny of the
procolophonids
in 2008, but excluded
Owenetta
from the family, only placing in the larger
Procolophonoidea
. So, brief mention of
Owenetta
is warranted. Slide4
OWENETTA Owenetta is a small parareptilian genus known form the Upper Permian to the Lower Triassic of South Africa.Slide5
Skull of OwenettaSlide6
Reisz and Scott (2002) considered Owenetta + Barasaurus (Late Permian, Madagascar) to belong to their own clade known as the Owenettidae characterized by:
a large postfrontal that prevents contact between the parietal and postorbital
a deep temporal
emargination
between the
jugal
and
quadratojugal
a rectangular
supratemporal
humerus
lacking
entepicondylar
foramen
The last character isn’t entirely useful, as there are other groups with this condition.Slide7
Reisz and Scott (2002) - Owenettidae
characterized by:
a large postfrontal that prevents contact between the parietal and
postorbital
a deep temporal
emargination
between the
jugal
and
quadratojugal
a rectangular
supratemporal
humerus
lacking
entepicondylar
foramenSlide8
PROCOLOPHONOIDEA Procolophonids have been variously placed, difficult to define, and not surprisingly considered as a potential ancestors to turtles. As a group they appear to hang together by virtue of the broadly flared shape of their cheeks. This is the first group we examine this term that survived the end-Permian extinction, persisting until the end of the Triassic.
Cisneros (2008) defined the group with the following features
:
Maxilla
premaxillary
subnarial
process absent.
External naris
subcircular
or
dorsoventrally
expanded.
Maxillary depression present.
Three to four
premaxillary
teeth.
Maxillary teeth with
labiolingually
expanded bases present.
Ten to 12 maxillary teeth.
Anterior
vomerine
dentition consisting of true teeth.Slide9
Maxilla premaxillary
subnarial
process absent
.
External naris
subcircular
or
dorsoventrally
expanded
.
Maxillary depression present
.
Three to four
premaxillary
teeth
.
Maxillary teeth with
labiolingually
expanded bases present
.
Ten to 12 maxillary teeth
.
Anterior
vomerine
dentition consisting of true teeth.Slide10Slide11