Calciavis
| Calciavis Temporal range:Eocene
| |
|---|---|
Scientific classification
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Infraclass: | Palaeognathae |
| Order: | †Lithornithiformes |
| Family: | †Lithornithidae |
| Genus: | †Calciavis Nesbitt et al. 2016 |
| Species | |
Calciavisis an extinct genus of bird from theEoceneofWyoming.It is alithornithid,a member of a lineage of flyingpalaeognaths,distantly related to modernratites.Like many other fossils from theGreen River Formation,its are exceptionally well preserved, bearing impressions of skin and feathers.[1]
Discovery and description
[edit]The original specimen ofCalciavis,AMNH 30578,was found in theFossil Butte Memberof theGreen River Formation,Wyoming,dating to around 51 million years ago. It is an exceptionally well preserved specimen, preserving most of the post-cranial skeleton aside from the femur and associated pelvic region, as well as soft-tissue impressions of feathers, skin,foot scalesand claw sheaths. Another specimen,AMNH 30560,was found in the vicinity, composed of a similarly complete most mostly disarticulate skeleton.
It is diagnosed by several features of the skull and pelvis as well as havingmetatarsalsIV and II subequal in distal extent. It differs from the contemporaryPseudocrypturusby a shorter skull - inCalciavisthe skull is shorter than the humerus, while in inverse happens inPseudocrypturus-, as well as a proportionally narrowercoracoidshaft and longertarsometatarsus,fromLithornis promiscuusin aspects of theischium,and fromParacathartesin a less curved and more gracile scapular blade.
Feather imprints show abundantplumagewith long primaries and remiges. In AMNH 30578 most of it is damaged due to post-mortem decomposition, with disorganised patches in the pectoral and pelvic region and the left wing traces and impressions being damaged, but the right wing is mostly intact, even showing evidence ofbarbules;in AMNH AMNH 30560 a wing is similarly well preserved. It is unclear if it had a tail, as the left wing feathers block the caudal region in AMNH 30578, but other lithornithids lack tail feathers.
Phylogeny
[edit]Calciavisis recovered as a sister taxa toPseudocrypturus,as sister-taxa to all other lithornithids.[citation needed]
Ecology
[edit]Studies suggest that there was bare minimum of two species-level lithornithids in theGreen River Formationat a given time, suggesting a high local diversity.Calciavisindeed co-existed directly at least withPseudocrypturus,and though both genera/species are the only currently diagnosable lithornithids several other contemporary species probably belong to separate species. Comparisons with other palaeognaths render the possibility of both birds being different sexes of the same species unlikely, and bothCalciavisspecimens belong to adult birds, not juveniles ofPseudocrypturus.
As mentioned above, skull and limb proportions are different among both species, implying that they occupied different ecological niches.
Flight
[edit]A recent study onCalciavisvindicates previous statements of competent flying in lithornithids, indicating that not only they were capable of sustained flapping but also migratory behaviour.[2]
See also
[edit]References
[edit]- ^Nesbitt, Sterling J.; Clarke, Julia A., The anatomy and taxonomy of the exquisitely preserved Green River Formation (early Eocene) lithornithids (Aves) and the relationships of Lithornithidae. (Bulletin of the American Museum of Natural History, no. 406), 2016-06-30
- ^Torres, Christopher R.; Norell, Mark A.; Clarke, Julia A. (2019)."Estimating Flight Style of Early Eocene Stem Palaeognath BirdCalciavisgrandei(Lithornithidae) ".The Anatomical Record.doi:10.1002/ar.24207.PMID31313482.
