[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
RE: pterosaur femora sprawl
David Marjanovic wrote:
> Remember *Onychonycteris*. It seems, to some degree, have used all five
Yes, exactly. The paper that David (Marjanovic) is referring to - and which
David (Peters) really needs to read - is...
Nancy B. Simmons, Kevin L. Seymour, Jörg Habersetzer, & Gregg F. Gunnell
(2007). Primitive Early Eocene bat from Wyoming and the evolution of flight and
echolocation. Nature 451: 818-821
Abstract: "Bats (Chiroptera) represent one of the largest and most diverse
radiations of mammals, accounting for one-fifth of extant species. Although
recent studies unambiguously support bat monophyly and consensus is rapidly
emerging about evolutionary relationships among extant lineages, the fossil
record of bats extends over 50 million years, and early evolution of the group
remains poorly understood. Here we describe a new bat from the Early Eocene
Green River Formation of Wyoming, USA, with features that are more primitive
than seen in any previously known bat. The evolutionary pathways that led to
flapping flight and echolocation in bats have been in dispute, and until now
fossils have been of limited use in documenting transitions involved in this
marked change in lifestyle. Phylogenetically informed comparisons of the new
taxon with other bats and non-flying mammals reveal that critical morphological
and functional changes evolved incrementally. Forelimb anatomy indicates
that the new bat was capable of powered flight like other Eocene bats, but ear
morphology suggests that it lacked their echolocation abilities, supporting a
'flight first' hypothesis for chiropteran evolution. The shape of the wings
suggests that an undulating gliding–fluttering flight style may be primitive
for bats, and the presence of a long calcar indicates that a broad tail
membrane evolved early in Chiroptera, probably functioning as an additional
airfoil rather than as a prey-capture device. Limb proportions and retention of
claws on all digits indicate that the new bat may have been an agile climber
that employed quadrupedal locomotion and under-branch hanging behaviour."
This paragraph (from the body of the paper) is also helpful...
"The discovery of _Onychonycteris_ indicates that claws on digits III–V were
lost after powered flight evolved. [snip] Reduction in the relative size of the
hind limbs also continued after the evolution of powered flight. The limb
proportions, the robust fibula and the retention of wing claws seen in
_Onychonycteris_ suggest that it was probably capable of more agile non-volant
locomotion (climbing either along tree branches or under them) than most other
bats, including other Eocene taxa, and may have incorporated quadrupedal
locomotion and under-branch hanging into its locomotory and roosting behaviour."
Enjoy 5 GB of free, password-protected online storage.