Sapeornis chaoyangensis sp. nov.

[Gerrit Hanenburg <G.Hanenburg@inter.NL.net>]

Zhou, Z. & Zhang, F. (2002). Largest bird from the Early Cretaceous
and its implications for the earliest avian ecological diversification.
Naturwissenschaften
89:34?38.

Some quotes from the paper:

Abstract: With only one known exception, early Cretaceous birds were
smaller than their closest theropod dinosaur relatives. Here we report on
a new bird from the Early Cretaceous feathered-dinosaur-bearing
continental deposits of Liaoning, northeast China, which is not only
larger than Archaeopteryx but is nearly twice as large as the basal
dromaeosaur Microraptor. The new taxon, Sapeornis chaoyangensis gen. et
sp. nov., has a more basal phylogenetic position than all other birds
except for Archaeopteryx. Its exceptionally long forelimbs,
well-developed deltoid crest of the humerus, proximally fused
metacarpals, relatively short hindlimbs and short pygostyle indicate
powerful soaring capability and further suggest that by the Early
Cretaceous ecological diversification of early birds was greater than
previously assumed. Electronic supplementary material to this paper can
be obtained by using the Springer LINK server located at
http://dx.doi.org/10.1007/s00114-001-0276-9.

Class Aves
Order and family indet.
Genus Sapeornis gen. nov.
Sapeornis chaoyangensis sp. nov.
Type specimen
Institute of Vertebrate Paleontology and Paleoanthropology
(IVPP), Beijing, China collection number V 12698

Etymology: SAPE is the abbreviation for the Society of Avian Paleontology
and Evolution. The fifth SAPE conference was held in China in June 2000,
shortly before the holotype was collected. The species name is derived
from the type locality ?Chaoyang?. 

Type locality: Shangheshou, Chaoyang City, Liaoning Province,
China.

Horizon: Jiufotang Formation, Early Cretaceous.

Diagnosis: Sapeornis possesses more derived features than Archaeopteryx,
such as a fused pygostyle. It is different from Confuciusornis in having,
among many features, a welldeveloped fibula and a significantly different
proximal end of the humerus. It differs from all the other avian taxa
described from the early Cretaceous of China in retaining many primitive
traits including the fifth metatarsal, the long first manual digit and
short coracoid. It is also distinguishable from other early Cretaceous
birds by possessing a large body size and extremely elongated forelimbs
[ratio of forelimb (humerus + ulna + carpometacarpus) to hindlimb (femur
+ tibiotarsus + tarsometatarsus) is 1.55], the deltoid crest of the
humerus measures about one-third of the length of the humerus, the
dorso-distal portion of the deltoid crest tapers into an acute process,
the tibiotarsus is shorter than the pubis, and the femur nearly as long
as the tibiotarsus.

Concerning its phylogenetic position, Sapeornis is found to be the most
primitive bird except for Archaeopteryx (Fig. 2; see Electronic
Supplementary Material). It shares several primitive features with
Archaeopteryx and dromaeosaurs, such as a short and nonstrut-like
coracoid, well developed manual digit I, a fibula reaching the distal end
of the tarsal joint, the presence of a free tarsal, and the presence of a
fifth metatarsal. On the other hand, Sapeornis exhibits more derived
characters than Archaeopteryx, such as the presence of heterocoelous
cervicals, the presence of a pygostyle, a fused carpometacarpus, pubic
symphysis about one third the length of the pubis, and the fact that the
ulna is longer than the humerus.

end quotes.

Gerrit