Confuciusornis
| Confuciusornis | ||||||||||||
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Live reconstruction of Confuciusornis sanctus |
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| Temporal occurrence | ||||||||||||
| Lower Cretaceous Period | ||||||||||||
| 125 to 110 million years | ||||||||||||
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| Scientific name | ||||||||||||
| Confuciusornis | ||||||||||||
| Hou , Zhou , Gu & Zhang , 1995 | ||||||||||||
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Confuciusornis is an ancient species of bird , the fossil remains of whichwere discoveredin sedimentary rocks of the Lower Cretaceous in the Chinese province of Liaoning . The completeness of numerous skeletons brought to light and well-preserved plumage - impressions make Confuciusornis one of the best known birds of the Mesozoic .
History of discovery and exploration
Even before feathered dinosaurs were found , which brought the People's Republic of China into the focus of paleontological research, the fossil remains of a bird about 30 centimeters tall were discovered in 1993 in the area around Sihetun and Jianshangou near the city of Beipiao , and in 1995 they were removed by a Chinese research group Lianhai Hou is described as “ Confuciusornis sanctus ” (“Holy Confucius Bird”). The site near Sihetun in particular has since proven to be very rich in bird fossils:
More than 1000 specimens of the genus Confuciusornis had been recovered there by the turn of the millennium. Confuciusornis sanctus was not the only species in the genus Confuciusornis : The research group named a total of three other species in 1997 and 1999, two of which, however, are controversial. With Liaoningornis in 1996 and Changchengornis in 1999, other new bird species were added from the same site. Unfortunately, many bird fossils were lost to science in the late 1990s due to the activities of predatory graves for paleontological research. By the time it was possible to protect the most important sites around Beipiao from illegal fossil hunters and traders, hundreds of specimens had been excavated and sold without having been scientifically examined.
In the first description of Confuciusornis was believed that the rock units of the Jehol Biota , to which the Fund layers in Sihetun and Jianshangou belong, would have a similar age as the Solnhofen limestone from which the primitive bird Archeopteryx comes. The results of radiometric dating of the rocks published in 1999 show, however, a lower age for the entire Jehol group ( Lower Cretaceous compared to Upper Jurassic ). The anatomically more modern bird Confuciusornis compared to Archeopteryx was therefore clearly the younger one.
Confuciusornis ' anatomy in comparison
Since the 1980s, when Archeopteryx was temporally and morphologically isolated from the other fossil birds known at the time, numerous mosaic forms have been discovered that filled the existing gap, Confuciusornis is one of them. Similar to the primitive bird, the appearance of Confuciusornis shows a striking mosaic of primitive features , i.e. those that were already developed in the ancestors of the birds (the theropod dinosaurs ), and derived features that were newly added in the course of bird evolution . They are listed in Table 1. "Non-bird-heropod" is an English term for theropod dinosaur in the conventional sense without including their descendants, the birds.
| Table 1: Ancestral and inferred characteristics in Confuciusornis compared to other groups | ||||
| anatomical feature |
theropod dinosaurs ("non-bird heropods") |
Archeopteryx | Confuciusornis | Higher birds (Ornithothoraces) |
|---|---|---|---|---|
| teeth | with many | + | - | with many chalk birds |
| two occipital openings (diapsid skull) | + | - | + | - |
| bony tail shortened, last caudal vertebrae fused to pygostyle |
with a few | - | + | + |
| Fork bone (furcula) | some ( boomerang-shaped ) |
boomerang-shaped | boomerang-shaped | acute-angled (V-shaped, fork-shaped) |
| Coracoid is long, strut-shaped |
- | - | + | + |
|
Breastbone (sternum) with sternum Kiel ( Carina ) |
- | - | - (but with some with a low crest) |
+ (for birds capable of flying) |
| Sternal ribs (ribs connected to the sternum) |
with some | - | + | + |
| Abdominal ribs (gastralia) | + | + | + | - |
| Ribs with a hooked process (uncinate process) |
with some | - | + | with many |
| Upper arm with an extensive perforated deltopectoral ridge ( autapomorphic ) |
- | - | + | - |
| Metacarpal bones I – III fused to form carpometacarpus |
- | - | + (Merging only near the wrist) |
+ |
| Metatarsal bones II – IV are fused to form the running leg (bird run, tarsometatarsus) |
with some | + | + | + |
| Metatarsal V present | + | + | + | - |
| asymmetrical flight springs | with some | + | + | + |
| Thumb wing (alula) | with a few | - | - | + |
The skull shows an unusual combination of features: the beak of Confuciusornis was edentulous, as in birds living today, while contemporary, more modern species of birds such as Liaoningornis and Yanornis still had teeth. In contrast, the temporal region was designed as in diapsid reptiles : two paired temple windows (the infratemporal and the supratemporal window ) were located behind the eye opening ( orbit ). In all other birds, including Archeopteryx , such temporal windows have not been demonstrated.
The flight apparatus of Confuciusornis was more advanced than that of Archeopteryx : The breastbone (sternum) in some specimens shows a flat crest that is reminiscent of the sternum keel (carina) of modern birds. An extensive sternum keel has been developed in all recent birds capable of flying as the starting point for the most important flight muscles for wing upstroke and downstroke . The coracoid, which is elongated compared to Archeopteryx , also shows the remodeling of the shoulder muscles in the direction of modern birds.
The rib cage of Confuciusornis was reinforced by hooked processes on the ribs and by so-called sternal ribs , i.e. rib elements connected to the sternum. The wishbone, on the other hand, as in Archeopteryx and various (non-bird) theropods, did not have a fork- shaped shape , but a boomerang- like shape.
In graphic reconstructions (see also the picture in the box above) Confuciusornis's hand looks rather primitive. Indeed, which were metacarpal bone ( metacarpal ) II and III near the wrist together with the crescent-shaped carpal bones to a Carpometacarpus fused. In modern birds, the fusions of the hand are so extensive that only one phalanx of the first finger is free to move: The "thumb" carries the so-called corner or thumb wing ( alula ), which is important for manipulating the air flow during certain flight maneuvers . According to current knowledge , Confuciusornis and Archeopteryx did not yet have such a thumb wing . With one exception ( Microraptor ), this feature is only developed in birds of the more highly developed group Ornithothoraces such as Eoalulavis ("formerly Alula bird").
The upper arm of Confuciusornis ends in an extensive pectoral ridge that has an oval opening. This opening, the function of which is unclear, was believed to be an autapomorphy , i.e. the exclusive feature of this genus. In 2002 the bird Sapeornis was described, which also comes from the rocks of the Jehol group and had a similar upper arm window. Accordingly, this trait may be more common among early birds than first thought.
Important innovations that distinguished Confuciusornis (and Sapeornis ) from even more primitive birds such as Archeopteryx , Rahonavis and Jeholornis were the shortening of the bony tail and the formation of a pygostyle by fusing the last caudal vertebrae. Such a modification of the tail skeleton was advantageous for flight navigation.
Systematics
Species of the genus Confuciusornis
Of the six species of the genus Confuciusornis described so far, two are invalid in the opinion of the research group headed by Luis M. Chiappe: Confuciusornis suniae and Confuciusornis chuonzhous are based on the misinterpretation of intraspecific differences of Confuciusornis sanctus . All specimens that were assigned to the two species belonged to C. sanctus like the majority of all finds .
Confuciusornis dui , the fourth species described in 1999, differs from C. sanctus in, among other things, the proportions of the hands, the shape and characteristics of several skull elements and the shape of the sternum and the ribs attached to the sternum. Two more species were described in 2009 and 2010, Confuciusornis feducciai named after the American paleornithologist Alan Feduccia and Confuciusornis jianchangensis .
Genera of the Confuciusornithidae family
The Confuciusornithidae family includes, in addition to Confuciusornis, the genus Changchengornis , which differs from the former in, among other things, a shorter beak, the lack of an upper arm window, the shape of some shoulder girdle elements and the length of the backward-facing first toe ( hallux ). The longer hallux is an indication that Changchengorni's branches could grip better than Confuciusorni's .
Common features of all members of the Confuciusornithidae family are the absence of teeth, the almost square shape of the deltopectoral ridge on the upper arm, the V-shaped rear edge of the sternum and the proportions of the hand claws.
The bird fossils described as Jinzhouornis in 2001 also come from the rocks of the Jehol group and can be assigned to the Confuciusornithidae family. So far there is no detailed description of this genus in English.
Relationships of Mesozoic Birds
| Aves (Avialae, birds) |
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( Cladogram based on Zhou 2004.)
The members of the Confuciusornithidae family belong to the most primitive forms within the Pygostylia group . In the ornithothoraces, the more highly developed representatives of this group, the number of vertebrae ( thoracals ) is reduced and the first finger forms a thumb wing (alula) (see also point 2 ). All representatives of modern bird orders are descendants of this group.
Flight ability and way of life
The flight ability of Confuciusornis is assessed differently by the various palaeornithological working groups. Confuciusornis had large, curved claws on its hands and feet. Based on this observation, the idea is that the Confuciusornis flying machine was not powerful enough to take off from the ground. Instead, Confuciusornis climbed trees with the help of his claws to begin the flapping flight from free fall .
This view contradicts that of the hind unspecialized and compared to recent on trees live birds was poorly adapted to the gripping of branches. In addition, the long flight springs may have been a hindrance when climbing. Opponents of the theory of the climbing Confuciusornis consider the various adaptations of the skeleton to the flight of birds to be sufficient, for example, to take off from the ground from the run. According to Peters and Qiang, the idea that Confuciusornis was only able to fly to a limited extent is absurd in view of the large wings. The latter also suggest that the representatives of the genus were good glider pilots .
Lianhai Hou's working group believes it is likely that Confuciusornis was a herbivore. Dalsätt and others, on the other hand, described a 2006 specimen of Confuciusornis sanctus from the Jiufotang Formation, which provided direct evidence of the type of diet: Several vertebrae and ribs of the teleostier Jinanichthys in the lower neck and front chest area of the bird skeleton indicate that Confuciusornis among other things ate fish. The fish bones were believed to be part of a ball of spits that the bird choked up shortly before it died. Dalsätt and others interpret the beak morphology of Confuciusornis as that of an omnivore similar to the recent crows - in their view, fish were a common part of the diet alongside seeds and / or other parts of plants.
Mass occurrences of Confuciusornis skeletons in the lake deposits at the Sihetun site indicate that the birds may have flocked to the shores of lakes. If there are more than 40 specimens per 100 square meters in some of the layers, the cause could have been the common death as a result of a natural disaster: In one of the frequent volcanic ash falls , the individuals died at the same time and their carcasses were washed into the lake from the lakeshore . From this theory it follows that individuals of the genus Confuciusornis, similar to representatives of many recent bird species, lived together in groups or met temporarily.
Sex dimorphism and mating behavior
The specimens of Confuciusornis differ in their fletching : About five to ten percent of the individuals have impressions of a pair of elongated tail feathers. According to various editors, one explanation for this difference could be gender. If this theory is correct, the earliest evidence of sexual dimorphism would be in birds.
The behavioral consequences of such a gender difference would be manifold: There could have been a form of partner choice in which individuals of one gender displayed their plumage in front of individuals of the other. If the males were the ones with the long tail feathers, the unequal ratio of the numbers of individuals indicates that there was a form of polygyny (" polygyny "). The laborious choice of the sexual partner by the female is, among other things, expedient and economical if the male takes part in brood care , for example protecting the clutch of the females he mates.
The difference in the fletching makes it clear that the birds of the Lower Cretaceous Period were likely to have had complex social behavior.
Growth and development
The evolution of growth patterns in birds has been studied using the limb bones of Confuciusornis sanctus and other early birds. Due to the constant growth of a bone from the inside out ( accretion ), changes in growth during the development of an individual can be traced in a similar way as with tree rings (see dendrochronology ). The differentiation of growth phases is made when analyzing a bone cross section under the microscope.
The bony cortex of Confuciusornis consists of fast-growing, well-perfused inner cortical tissue, which resembles the fibrolamellar tissue of today's birds, and a slowly growing outer cortical tissue. The latter was internally more zoned and interspersed with fewer blood vessels, it represents the later growth of the bird. In 2003, De Ricqlès and others used bone histological studies to show that Confuciusornis was fully grown in 20 weeks or a little less. This time span is long compared to most recent bird species, but a little shorter than the often larger coelurosaurs . Apparently, early birds achieved a reduction in adult body size ( dwarfism ) by shortening the early phase of rapid growth, which is represented by the inner cortical tissue, compared to their dinosaur ancestors.
The evidence of fibrolamellar tissue in Confuciusornis nevertheless shows that, contrary to previously assumed, primitive birds (like their ancestors and descendants) showed phases of rapid growth; so they already had a sufficiently high metabolism to maintain high growth rates. The slowly growing bone tissue of the enantiornithiformes , which was initially considered to be an example of primeval birds, apparently represents a subsequent slowdown in growth that was not yet present in the first birds and in Confuciusornis . Very high growth rates, as shown by modern birds, then emerged secondarily in the course of the Cretaceous period .
A special development strategy is also being discussed as a possible cause for slow growth rates in early birds: Fossil embryos of the chalk bird Gobipteryx show a well-developed ossified wing skeleton, which allows the conclusion that representatives of this genus and perhaps primeval birds in general were extremely precocious and already fleeing nest could fly shortly after hatching. According to this theory, much of the juvenile's energy would be used to fly and would therefore not be available for growth. This condition would only be overcome in bird species that carried out intensive brood and offspring care. As a result, the young birds do not have to be able to fledge and survive without the help of their parents immediately after birth, but can invest a large part of the energy absorbed through food in growth.
The importance of Confuciusornis as an element of Jehol- avifaunae
In the following stratigraphic table the find layers of the Jehol group and the bird species described in each case are listed from older (below) to younger (above) .
| Table 2: composition of the Jehol- avifaunae in stratigraphic sequence | ||||
| formation | Layer member | primeval birds | Ornithothoraces | |
| Enantiornithes | Ornithurae | |||
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Jiufotang formation |
Confuciusornis sp., Sapeornis chaoyangensis, Jeholornis prima |
Sinornis santanensis, Longchengornis sanyanensis, Cuspirostrisornis houi, Largirostrornis sexdentorius, Boluochia zhengi, Longipteryx chaoyangensis |
Chaoyangia beishanensis, Yanornis martini, Yixianornis grabaui, Songlingornis linghensis |
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Yixian formation |
Jingangshan layers |
Confuciusornis sp. | --- | --- |
| Dawangzhangzi layers |
Confuciusornis sp. |
Liaoxiornis delicatus, Liaoxiornis sp., Jibeinia luanhera |
--- | |
| Jianshangou layers |
Confuciusornis sanctus, Confuciusornis dui, Changchengornis hengdaoziensis |
Protopteryx fengningensis, Eoenantiornis buhleri |
Liaoningornis longiditris | |
In contrast to the other bird genera, Confuciusornis occurred in the sediments of the Jehol group for more than 15 million years, i.e. almost during the entire formation period. This observation shows that, despite its comparatively poorly developed flight characteristics , Confuciusornis was able to prevail against competing birds with more advanced blueprints .
In the sequence, however, there is a trend towards more developed birds. At the latest during the formation of the Jiufotang Formation , the enantiornithes dominated , a group that dominated many ecosystems until they became extinct at the end of the Cretaceous Period . Interestingly, the bird species Jeholornis , which was even more similar to the primordial bird Archeopteryx than Confuciusornis , did not appear until the end of the Jehol group's educational period.
See also : paleornithology
literature
General, history
- Ursula B. Göhlich, Gerald Mayr: A visit to Confuciusornis & Co. in northeast China. In: Nature and Museum. 131, No. 11, 2001, pp. 401-409.
- Erik Stokstad: Exquisite Chinese Fossils Add New Pages to Book of Life. In: Science . 291, No. 5502, 2001, pp. 232-236, doi : 10.1126 / science.291.5502.234 .
- Carl C. Swisher III, Yuan-Qing Wang, Xiao-Lin Wang, Xing Xu, Yuan Wang: Cretaceous age for feathered dinosaurs of Liaoning, China. In: Nature . 400, No. 6739, 1999, pp. 58-61, doi : 10.1038 / 21872 .
- Zhong-He Zhou, Lianhai Hou: The Discovery and Study of Mesozoic Fossil Birds in China. In: Luis M. Chiappe, Lawrence M. Witmer (Eds.): Mesozoic Birds. Above the Heads of the Dinosaurs. University of California Press, Berkeley 2002, ISBN 0-520-20094-2 , pp. 160-182.
Anatomy, systematics, phylogenesis
- Luis M. Chiappe, Shu'an Ji, Qiang Ji, Mark A. Norell: Anatomy and Systematics of the Confuciusornithidae (Theropoda: Aves) from the Late Mesozoic of Northeastern China. (PDF; 9.7 MB) In: Bulletin of the American Museum of Natural History. No. 242, 1999, p. 98.
- Dieter Stefan Peters: An almost complete skeleton of a primeval bird from China. In: Nature and Museum. 126, No. 9, 1996, pp. 198-302.
- Dieter Stefan Peters, Ji Qiang: The diapsid temporal construction of the Chinese fossil bird Confuciusornis. In: Senckenbergiana lethaea. 78, No. 1-2, 1998, pp. 153-155, doi : 10.1007 / BF03042766 .
- Andrea Goernemann: Osteology of a copy of Confuciusornis from the lower chalk of West Liaoning, China. In: Archeopteryx. 17, 1999, pp. 41-54.
- Andrzej Elzanowski, Albrecht Manegold , Dieter Stefan Peters: Redescription of a skull of Confuciusornis sanctus. In: Archeopteryx. 23, 2005, pp. 51-55.
- Lianhai Hou, Zhong-He Zhou, Larry D. Martin, Alan Feduccia: A beaked bird from the Jurassic of China. In: Nature. 377, No. 6550, 1995, pp. 616-618, doi : 10.1038 / 377616a0 .
- Qiang Ji, Luis M. Chiappe, Shu'an Ji: A new Late Mesozoic confuciusornithid bird from China. In: Journal of Vertebrate Paleontology. 19, No. 1, 1999, pp. 1-7.
- Larry D. Martin, Zhong-He Zhou, Lian-Hai Hou, Alan Feduccia: Confuciusornis sanctus compared to Archeopteryx lithographica . In: Natural Sciences. 85, No. 6, 1998, pp. 286-289, doi : 10.1007 / s001140050501 .
- Qicheng Wu: Fossil Treasures from Liaoning. Geological Publishing House, Beijing 2002, ISBN 0-520-20094-2 .
- Zhong-He Zhou: The origin and early evolution of birds: discoveries, disputes and perspectives from fossil evidence. In: Natural Sciences. 91, No. 10, 2004, pp. 455-471, doi : 10.1007 / s00114-004-0570-4 .
Flight ability, way of life, social behavior, reproduction
- Luis M. Chiappe, Shu'an Ji, Qiang Ji, Mark A. Norell: see above
- J. Dalsätt, Z. Zhou, F. Zhang, P. G. P. Ericson: Food remains in 'Confuciusornis sanctus' suggest a fish diet. In: Natural Sciences. 93, No. 9, 2006, doi : 10.1007 / s00114-006-0125-y .
- J. David Ligon: The Evolution of Avian Breeding Systems. Oxford University Press, Oxford 1999, ISBN 0-19-854913-X .
- Dieter Stefan Peters, Qiang Ji: Did Confuciusornis have to climb? In: Journal of Ornithology. 140, No. 1, 1999, pp. 41-50.
- David J. Varricchio, Frankie D. Jackson: Origins of avian reproduction: answers and questions from dinosaurs. In: Palaeovertebrata. 32, No. 2-4, 2003, pp. 149-169.
Growth, individual development
- Anusuya Chinsamy, Andrzey Elzanowski: Evolution of growth patterns in birds. In: Nature. 412, No. 6845, 2001, pp. 402-403 doi : 10.1038 / 35086650 .
- Kevin Padian, Armand J. de Ricqlès, John R. Horner: Dinosaurian growth rates and bird origins. In: Nature. 412, 2001, pp. 405-408, doi : 10.1038 / 35086500 .
- AJ de Ricqlès, K. Padian, J. R. Horner, E.-T. Lamm, N. Myhrvold: Osteohistology of Confuciusornis sanctus (Theropoda: Aves). In: Journal of Vertebrate Paleontology 23, No. 2, pp. 373-386.
Biostratigraphy of the Jehol group
- Xiao-lin Wang et al. a .: Vertebrate Biostratigraphy of the Lower Cretaceous Yixian Formation in Lingyuan, Western Liaoning and its neighboring southern Nei Mongol (Inner Mongolia), China. In: Vertebrata PalAsiatica. 38, No. 2, 2000, pp. 81-99.
- Zhonghe Zhou, Paul M. Barett, Jason Hilton: An exceptionally preserved Lower Cretaceous ecosystem. In: Nature. 421, No. 6925, 2003, pp. 807-814, doi : 10.1038 / nature01420 .
Individual evidence
- ↑ L. Hou, Z. Zhou, Y. Gu, H. Zhang: Confuciusornis sanctus, a new Late Jurassic sauriurine bird from China. In: Chinese Science Bulletin. 40, No. 18, 1995, pp. 1545-1551.
- ↑ LM Chiappe, J. Shu'an, J. Qiang, M. Norell: Anatomy and Systematics of the Confuciusornithidae (Theropoda: Aves) from the Late Mesozoic of Northeastern China. (PDF; 9.7 MB) In: Bulletin of the American Museum of Natural History. No. 242, 1999, p. 98.
- ↑ Z. Zhang, C. Gao, Q. Meng, J. Liu, L. Hou and G. Zheng. 2009. Diversification in an Early Cretaceous avian genus: evidence from a new species of Confuciusornis from China. Journal of Ornithology 150 (4): 783-790
- ↑ L. Li, J.-q. Wang, and S.-l. Hou. 2010. A new species of Confuciusornis from Lower Cretaceous of Jianchung, Liaoning, China. Global Geology 29 (2): 183-187
- ↑ Dieter Stefan Peters, Ji Qiang: The diapsid temporal construction of the Chinese fossil bird Confuciusornis. In: Senckenbergiana lethaea. 78, No. 1-2, 1998, pp. 153-155, doi : 10.1007 / BF03042766 .
- ↑ L. Hou, L. D. Martin, Z. Zhou, A. Feduccia, F. Zhang: A diapsid skull in a new species of the primitive bird 'Confuciusornis'. In: Nature. 399, 1999, p. 680, doi : 10.1038 / 21411 .
- ↑ J. Dalsätt, Z. Zhou, F. Zhang, P. G. P. Ericson: Food remains in 'Confuciusornis sanctus' suggest a fish diet . In: Natural Sciences. 93, No. 9, 2006, doi : 10.1007 / s00114-006-0125-y .
- ↑ A. J. de Ricqlès et al. a .: Osteohistology of Confuciusornis sanctus (Theropoda: Aves). In: Journal of Vertebrate Paleontology. 23, No. 2, 2003, pp. 373-386.
- ↑ Anusuya Chinsamy, Andrzey Elzanowski: Evolution of growth patterns in birds. In: Nature. 412, No. 6845, 2001, pp. 402-403 doi : 10.1038 / 35086650 .
