Ascendonanus

Ascendonanus
Temporal range: Early Permian, ~290 Ma
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Skull of Ascendonanus reconstructed in lateral view
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Synapsida
Family:
†Varanopidae
Genus:
†Ascendonanus

Spindler et al., 2018
Type species
†Ascendonanus nestleri
Spindler et al., 2018

Ascendonanus (meaning "climbing dwarf") is an extinct genus of varanopid amniote from the Early Permian of Germany.[1] It is one of the earliest specialized arboreal (tree-living) tetrapods currently known and outwardly resembled a small lizard. The animal was about 40 cm long, with strongly curved claws, short limbs, a slender, elongated trunk, and a long tail. It would have preyed on insects and other small arthropods.[1][2]

The taxonomic position of varanopids is currently debated between synapsids (related to mammals, the most widely accepted idea) and diapsids (related to reptiles). The fossils of Ascendonanus are of special scientific importance because they include remains of skin, scales, scutes, bony ossicles, and soft-tissue body outlines, which could indicate that some of the oldest relatives of mammals had a scaly "reptilian-type" appearance.

The related small varanopid Eoscansor, recently described from New Mexico, was also adapted to climbing, very likely in trees, but dates from 15 million years earlier during the Pennsylvanian subperiod of the Carboniferous, indicating that climbing varanopids have a longer history and were likely widespread.[3]

Ascendonanus was named and described in 2018 from remains of five individuals that were discovered in the Chemnitz petrified forest, an Early Permian tropical fossil forest preserved under the city of Chemnitz, Germany. A Pompeii-like pyroclastic volcanic eruption 291 million years ago[4] buried the forest and created the Zeisigwald Tuff Horizon in the uppermost Leukersdorf Formation (late Sakmarian/early Artinskian transition stage), preserving some of the animals that lived there in exceptional detail in a bottom layer of volcanic ash.[1]

The type species name Ascendonanus nestleri honors Knut Nestler, a long-time local supporter (deceased) of the Chemnitz Museum of Natural History (Museum für Naturkunde Chemnitz (MNC)), where the specimens of Ascendonanus are stored.[1]

  1. ^ a b c d Frederik Spindler; Ralf Werneburg; Joerg W. Schneider; Ludwig Luthardt; Volker Annacker; Ronny Rößler (2018). "First arboreal 'pelycosaurs' (Synapsida: Varanopidae) from the early Permian Chemnitz Fossil Lagerstätte, SE Germany, with a review of varanopid phylogeny". PalZ. 92 (2): 315–364. doi:10.1007/s12542-018-0405-9. S2CID 133846070.
  2. ^ Ascendonanus nestleri • First Arboreal 'Pelycosaurs' (Synapsida: Varanopidae) from the early Permian Chemnitz Fossil Lagerstätte, SE Germany http://novataxa.blogspot.com/2018/03/ascendonanus.html
  3. ^ Lucas, Spencer G.; Rinehart, Larry F.; Celeskey, Matthew; Berman, David S. (2022). "A SCANSORIAL VARANOPID EUPELYCOSAUR FROM THE PENNSYLVANIAN OF NEW MEXICO". Annals of Carnegie Museum. 87 (3): 167–205. doi:10.2992/007.087.0301. S2CID 250015681.
  4. ^ Ludwig Luthardt; Mandy Hofmann; Ulf Linnemann; Axel Gerdes; Linda Marko; Ronny Rößler (2018). "A new U-Pb zircon age and a volcanogenic model for the early Permian Chemnitz Fossil Forest". International Journal of Earth Sciences. 107 (7): 2465–2489. Bibcode:2018IJEaS.107.2465L. doi:10.1007/s00531-018-1608-8. S2CID 133884490.