Sapeornis
Encyclopedia
Sapeornis is a genus
of primitive bird
which lived during the Early Cretaceous
(late Aptian
to early Albian
, roughly 120-110 mya). The genus contains only the species Sapeornis chaoyangensis which is known from fossils found in Jiufotang Formation
rocks near Chaoyang, PRC
. Several nearly complete skeletons have been found.
Sapeornis is named for SAPE, the Society of Avian Paleontology and Evolution, added to the Ancient Greek
όρνις (ornis), meaning "bird". chaoyangensis is Latin
for "from Chaoyang".
and some peculiar similarities with oviraptorosaurs
such as Caudipteryx
, it is usually considered to be fairly close to Omnivoropteryx
.
The hand of Sapeornis was far more advanced than that of Archaeopteryx
. It had three fingers, the outer ones with two and the middle one with three phalanges, and a well-fused carpometacarpus
. Its arms were about half again as long as the legs, suggesting a large wing area. On the other hand, its shoulder girdle was apparently ill-adapted to flapping flight and its furcula
was unusual, with the hypocleidum of more advanced birds but a general conformation even more primitive than in Archaeopteryx. The humerus
was large and bore holes, apparently to save weight, as in the Confuciusornithidae
.
The skull has a handful of teeth in the upper jawtip only. It was altogether similar to Archaeopteryx, but even more so to small oviraptorosaurs and Omnivoropteryx. Sapeornis had gastralia
but no (or unossified) uncinate process
es. A sternum
was either not present or small and easily lost. The pygostyle
was rod-like as in Confuciusornis
and Nomingia
, but like in the former there was no long bony tail anymore. While the tarsometatarsi
were more fused than in Archaeopteryx, the fibula was long and reached the distal point of the tarsal joint, not reduced as in more modern birds (and some non-avian theropods like Avimimus
). The first toe pointed backwards. In specimen IVPP
V12375, the stomach contained numerous small gastrolith
s. Analysis of its skeletal bones suggest that it had an ontogeny
and slow growth like Archaeopteryx
and small carnivorous dinosaurs, rather than the explosively fast growth seen in living birds.
In absolute number of features shared with modern birds, S. chaoyangensis is about as advanced as Confuciusornis. However, the apomorphies were largely different from Confuciusornis, and a character analysis demonstrates that these two were not closely related. As its plumage is not known yet, the airfoil
shape of Sapeornis is unknown. As indicated by the slender pygostyle, its tail plumage was probably short as in the Enantiornithes
and Confuciusornis, with at most two to four long tail feathers. The reduced fingers suggest that it might have had an alula
. Not being well-adapted to flapping flight, Sapeornis probably was a glider and/or soarer that preferred more open country compared to the Enantiornithes and other predominantly woodland birds, although it was able to perch on branches. The small gastroliths, overall large size, and the inferred habitat indicate that Sapeornis was most likely a herbivore
, possibly eating plant seeds and fruits.
Comparisons between the scleral ring
s of Sapeornis and modern birds and reptiles indicate that it may have been diurnal, similar to most modern birds.
and Shenshiornis
are also likely synonymous with Sapeornis.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of primitive bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
which lived during the Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
(late Aptian
Aptian
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 112.0 ± 1.0 Ma , approximately...
to early Albian
Albian
The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous epoch/series. Its approximate time range is 112.0 ± 1.0 Ma to 99.6 ± 0.9 Ma...
, roughly 120-110 mya). The genus contains only the species Sapeornis chaoyangensis which is known from fossils found in Jiufotang Formation
Jiufotang Formation
The Jiufotang Formation is an Early Cretaceous geological formation in Chaoyang, Liaoning which has yielded fossils of feathered dinosaurs, primitive birds, pterosaurs, and other organisms. . It is a member of the Jehol group. The exact age of the Jiufotang has been debated for years, with...
rocks near Chaoyang, PRC
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
. Several nearly complete skeletons have been found.
Sapeornis is named for SAPE, the Society of Avian Paleontology and Evolution, added to the Ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
όρνις (ornis), meaning "bird". chaoyangensis is Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
for "from Chaoyang".
Description
This animal was about 30–33 cm long in life, excluding the tail feathers (which are unknown). From its general morphologyMorphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
and some peculiar similarities with oviraptorosaurs
Oviraptorosauria
Oviraptorosaurs are a group of feathered maniraptoran dinosaurs from the Cretaceous Period of what are now Asia and North America. They are distinct for their characteristically short, beaked, parrot - like skulls, with or without bony crests atop the head...
such as Caudipteryx
Caudipteryx
Caudipteryx is a genus of peacock-sized theropod dinosaurs that lived in the Aptian age of the early Cretaceous Period . They were feathered and remarkably birdlike in their overall appearance....
, it is usually considered to be fairly close to Omnivoropteryx
Omnivoropteryx
Omnivoropteryx is a genus of primitive flying bird from the early Cretaceous Upper Jiufotang Formation of China...
.
The hand of Sapeornis was far more advanced than that of Archaeopteryx
Archaeopteryx
Archaeopteryx , sometimes referred to by its German name Urvogel , is a genus of theropod dinosaur that is closely related to birds. The name derives from the Ancient Greek meaning "ancient", and , meaning "feather" or "wing"...
. It had three fingers, the outer ones with two and the middle one with three phalanges, and a well-fused carpometacarpus
Carpometacarpus
The carpometacarpus is the fusion of the carpal and metacarpal bone, essentially a single fused bone between the wrist and the knuckles. It is a smallish bone in most birds, generally flattened and with a large hole in the middle. In flightless birds, however, its shape may be slightly different,...
. Its arms were about half again as long as the legs, suggesting a large wing area. On the other hand, its shoulder girdle was apparently ill-adapted to flapping flight and its furcula
Furcula
The ' is a forked bone found in birds, formed by the fusion of the two clavicles. In birds, its function is the strengthening of the thoracic skeleton to withstand the rigors of flight....
was unusual, with the hypocleidum of more advanced birds but a general conformation even more primitive than in Archaeopteryx. The humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
was large and bore holes, apparently to save weight, as in the Confuciusornithidae
Confuciusornithidae
Confuciusornithidae is a family of primitive birds from the early Cretaceous Period of China. It consists of four genera. About half of all the confuciusornithid specimens, including reprersentatives of all species, that have preserved feathers possess a pair of distinctive ribbon-like tail...
.
The skull has a handful of teeth in the upper jawtip only. It was altogether similar to Archaeopteryx, but even more so to small oviraptorosaurs and Omnivoropteryx. Sapeornis had gastralia
Gastralium
Gastralia are dermal bones found in the ventral body wall of crocodilian and Sphenodon species. They are found between the sternum and pelvis, and do not articulate with the vertebrae...
but no (or unossified) uncinate process
Uncinate process
Uncinate process can refer to:* Uncinate process of ethmoid bone* Uncinate process of vertebra - a hook shaped process on the lateral borders of the superior surface of the vertebral bodies of the third to the seventh cervical vertebrae....
es. A sternum
Sternum
The sternum or breastbone is a long flat bony plate shaped like a capital "T" located anteriorly to the heart in the center of the thorax...
was either not present or small and easily lost. The pygostyle
Pygostyle
Pygostyle refers to a number of the final few caudal vertebrae fused into a single ossification, supporting the tail feathers and musculature. In modern birds, the rectrices attach to these....
was rod-like as in Confuciusornis
Confuciusornis
Confuciusornis is a genus of primitive crow-sized birds from the Early Cretaceous Yixian and Jiufotang Formations of China, dating from 125 to 120 million years ago...
and Nomingia
Nomingia
Nomingia is a genus of oviraptorid theropod dinosaur hailing from the Late Cretaceous Bugin Tsav Beds of Mongolia.-Discovery and naming:...
, but like in the former there was no long bony tail anymore. While the tarsometatarsi
Tarsometatarsus
The tarsometatarsus is a bone that is found in the lower leg of certain tetrapods, namely birds.It is formed from the fusion of several bones found in other types of animals, and homologous to the mammalian tarsal and metatarsal bones...
were more fused than in Archaeopteryx, the fibula was long and reached the distal point of the tarsal joint, not reduced as in more modern birds (and some non-avian theropods like Avimimus
Avimimus
Avimimus , meaning "bird mimic" , was a genus of bird-like maniraptoran dinosaur that lived in the late Cretaceous in what is now Mongolia, around 70 million years ago.-Description:...
). The first toe pointed backwards. In specimen IVPP
Institute of Vertebrate Paleontology and Paleoanthropology
The Institute of Vertebrate Paleontology and Paleoanthropology of China is a prominent research institution and collections repository for fossils, including many dinosaur and pterosaurand cat poo specimens...
V12375, the stomach contained numerous small gastrolith
Gastrolith
A gastrolith, also called a stomach stone or gizzard stones, is a rock held inside a gastrointestinal tract. Gastroliths are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. The grain size depends upon the size of the animal and the gastrolith's...
s. Analysis of its skeletal bones suggest that it had an ontogeny
Ontogeny
Ontogeny is the origin and the development of an organism – for example: from the fertilized egg to mature form. It covers in essence, the study of an organism's lifespan...
and slow growth like Archaeopteryx
Archaeopteryx
Archaeopteryx , sometimes referred to by its German name Urvogel , is a genus of theropod dinosaur that is closely related to birds. The name derives from the Ancient Greek meaning "ancient", and , meaning "feather" or "wing"...
and small carnivorous dinosaurs, rather than the explosively fast growth seen in living birds.
In absolute number of features shared with modern birds, S. chaoyangensis is about as advanced as Confuciusornis. However, the apomorphies were largely different from Confuciusornis, and a character analysis demonstrates that these two were not closely related. As its plumage is not known yet, the airfoil
Airfoil
An airfoil or aerofoil is the shape of a wing or blade or sail as seen in cross-section....
shape of Sapeornis is unknown. As indicated by the slender pygostyle, its tail plumage was probably short as in the Enantiornithes
Enantiornithes
Enantiornithes is an extinct group of primitive birds. They were the most abundant and diverse avialans of the Mesozoic. Almost all retained teeth and clawed fingers on each wing, but otherwise looked much like modern birds externally. Over 50 species of Enantiornithines have been named, but some...
and Confuciusornis, with at most two to four long tail feathers. The reduced fingers suggest that it might have had an alula
Alula
The alula, or bastard wing, is a small projection on the anterior edge of the wing of modern birds. The alula is the freely moving first digit, a bird's "thumb," and is typically covered with three to five small feathers, with the exact number depending on the species...
. Not being well-adapted to flapping flight, Sapeornis probably was a glider and/or soarer that preferred more open country compared to the Enantiornithes and other predominantly woodland birds, although it was able to perch on branches. The small gastroliths, overall large size, and the inferred habitat indicate that Sapeornis was most likely a herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
, possibly eating plant seeds and fruits.
Comparisons between the scleral ring
Sclerotic ring
Sclerotic rings are rings of bone found in the eyes of several groups of vertebrate animals, except for mammals and crocodilians. They can be made up of single bones or small bones together. They are believed to have a role in supporting the eye, especially in animals whose eyes are not spherical,...
s of Sapeornis and modern birds and reptiles indicate that it may have been diurnal, similar to most modern birds.
Classification and species
In 2008, Yuan named a new specimen related to Sapeornis as Didactylornis jii. Yuan concluded that Didactylornis differed from Sapeornis in the proportions of the foot and number of wing and foot bones. However, the relevant portions of the specimen were badly crushed, and later authors concluded that these differences were based on misinterpretation of the poorly preserved specimen. In a 2010 survey of Chinese fossil birds, Li and colleagues considered Didactylornis a synonym of Sapeornis chaoyangensis. OmnivoropteryxOmnivoropteryx
Omnivoropteryx is a genus of primitive flying bird from the early Cretaceous Upper Jiufotang Formation of China...
and Shenshiornis
Shenshiornis
Shenshiornis is a genus of primitive bird which existed in China during the early Cretaceous period. It is known from one partial skeleton recovered from he Jiufotang Formation of Liaoning province, dating to . The type species is Shenshiornis primita...
are also likely synonymous with Sapeornis.