| Alcmonavis | |
|---|---|
 | |
| Holotype specimen | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Clade: | Avialae |
| Genus: | †Alcmonavis Rauhutet al., 2019 |
| Type species | |
| †Alcmonavis poeschli Rauhutet al., 2019 | |
Alcmonavis is a basalgenus ofavialandinosaur that during theLate Jurassic lived in the area of presentGermany. The only named species in the genus isAlcmonavis poeschli. Its only known fossil was originally reported as a specimen ofArchaeopteryx.
Amateur paleontologist Roland Pöschl systematically excavates the Alte Schöpfel quarry on the Schaudiberg, at Mühlheim nearMörnsheim inBavaria. In November 2017, he discovered a slab showing a right wing of a primordial bird. The piece was prepared by Uli Leonhardt.[1] In 2018, it was reported as a thirteenth specimen ofArchaeopteryx. Subsequent research, however, indicated that it represented a species new to science.
In 2019, thetype speciesAlcmonavis poeschli was named and described by Oliver Walter Mischa Rauhut, Helmut Tischlinger and Christian Foth. The generic name combines the old Celtic name of theAltmühl River meandering through the region of the find, Alcmona, with aLatinavis, "bird". Thespecific name honours Pöschl as discoverer.[1]
Theholotype, specimenSNSB-BSPG 2017 I 133, has been found in a layer of theMörnsheim Formation dating from the earlyTithonian. It consists of a nearly complete but only partially articulated right wing. The fossil is part of the collection of theBayerische Staatssammlung für Paläontologie und Geologie after being purchased by the Bavarian state.[1]
The length of the holotype was estimated at 111% of that of the largest knownArchaeopteryx specimen, the Solnhofener exemplar. The estimated humerus length is about nine centimetres.
Noautapomorphies, unique derived traits, ofAlcmonavis could be established. However, a unique combination of traits that in themselves are not unique was indicated. The humerus has a large deltopectoral crest, the expansion of which exceeds the shaft width. The upper side of the humerus makes an angle of 38° with the lower shaft. The ulna has a single and clearly distinct oval depression in its upper articulation surface, next to a small laterally projected process. The lower end of the ulna is slightly asymmetrically expanded. The radius at its top has a large crest-like process for the attachment of themusculus biceps brachii. The radius has a groove running along the inner side of its shaft. The secondmetatarsal is considerably more robust than the first or third metatarsal. The first phalanx of the first finger shows a longitudinal groove. The first phalanx of the second finger is very robust with an oval instead of flattened cross-section. The first phalanx of the second finger is warped around its long axis. The hand claws possess well-developed bosses for the flexor tendons, which processes are expanded at the palmar side.[1]
Rauhutet al (2019) placedAlcmonavis in abasal position in theAvialae, just aboveArchaeopteryx in the evolutionary tree. Thecladogram below displays the results of theirphylogenetic analyses.[1]
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