Haenamichnus

Haenamichnus Temporal range: Campanian 81–79  Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Trackway of H. sp. (A), and holotype of H. uhangriensis (B and C)
Trace fossil classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Order:	† Pterosauria
Suborder:	† Pterodactyloidea
Family:	† Azhdarchidae
Ichnofamily:	† Agadirichnidae
Ichnogenus:	† Haenamichnus Hwang et al., 2002
Type ichnospecies
†Haenamichnus uhangriensis Hwang et al., 2002

Haenamichnus is an ichnogenus of probable azhdarchid pterosaurs from the Late Cretaceous (Campanian) of South Korea. The type and only ichnospecies is H. uhangriensis, representing the largest known trace fossil made by a pterosaur.

Discovery and naming

In 2002, paleontologists Koo-Geun Hwang, Min Huh, Martin Lockley, David Unwin and Joanna Wright named the type ichnospecies Haenamichnus uhangriensis, based on fossil tracks they found in the Uhangri Formation of South Korea. The ichnogeneric name means 'trace of Haenam County', while the ichnospecific name is in reference to the Uhangri Formation. ^[1] The age of the Uhangri Formation is estimated around 81 to 79 million years ago during the Campanian stage. ^[2] Some Campanian azhdarchid tracks found in the Cerro del Pueblo Formation of Mexico and the Wapiti Formation of Canada might belong to this ichnogenus. ^{[3] [4]}

Formerly assigned ichnospecies

A putative second ichnospecies, H. gainensis, was reported from the Early Cretaceous (Albian) Haman Formation, but this ichnotaxon is now reassigned to as the archosaur trace fossil Batrachopus cf. grandis, made by either a bipedal crocodylomorph or therizinosaur. ^{[5] [6]}

Classification

The trackmaker of Haenamichnus uhangriensis is probably a large azhdarchid pterosaur, ^[1] likely reaching 10 m (33 ft) in wingspan, 3 m (9.8 ft) in height and 145 kg (320 lb) in body mass, more than ten times heavier than the Kori bustard. ^{[7] [8]} Meanwhile, much common and smaller Haenamichnus sp. tracks from the Uhangri Formation is consistent with medium-sized azhdarchids reaching 5–6 metres (16–20 ft) in wingspan. ^[1]

Azhdarchids are the only group of pterosaurs to which trackways have been assigned, including Haenamichnus which matches this group in shape, age, and size. One long trackway of this kind shows that azhdarchids walked with their limbs held directly underneath their body, and along with the morphology of their feet indicates they were more proficient on the ground than other pterosaurs. According to Witton, their proportions indicate they were not good swimmers on the other hand, and though they could probably launch from water, they were not as good at this as some other pterosaur groups. ^[9]

Haenamichnus was initially classified within the ichnofamily Pteraichnidae, ^[1] but Masrour et al. (2018) included both Agadirichnus and Haenamichnus within their newly proposed ichnofamily, Agadirichnidae. ^[10] Although it is notable for being the largest known pterosaur track, because the type series is rather poorly preserved and lacks stable shape, a redescription with more specimens of this ichnogenus might be required to confirm its ichnotaxonomic validity. ^[11]

See also

• Timeline of pterosaur research
• Ichnology
• Pterosaur ichnogenera

References

1. Hwang, K.G.; Huh, M.; Lockley, M.; Unwin, D.; Wright, J.L. (2002). "New pterosaur tracks (Pteraichnidae) from the Late Cretaceous Uhangri Formation, SW Korea" (PDF). Geological Magazine. 139 (4): 421–435. doi:10.1017/S0016756802006647. S2CID   54996027.
2. Kim, C.B.; Kim, J.M.; Huh, M. (2008). "Age and stratification of dinosaur eggs and clutches from Seonso Formation, South Korea" (PDF). Journal of the Korean Earth Science Society. 29 (5): 386–395. doi:10.5467/JKESS.2008.29.5.386.
3. Witton, Mark P.; Naish, Darren; McClain, Craig R. (28 May 2008). "A Reappraisal of Azhdarchid Pterosaur Functional Morphology and Paleoecology". PLOS ONE. 3 (5): e2271. Bibcode:2008PLoSO...3.2271W. doi: 10.1371/journal.pone.0002271 . PMC   2386974 . PMID   18509539.
4. Bell, P.R.; Fanti, F.; Sissons, R. (2013). "A possible pterosaur manus track from the Late Cretaceous of Alberta". Lethaia. 46 (2): 274–279. doi:10.1111/let.12006.
5. Kim, Kyung Soo; Lockley, Martin G.; Lim, Jong Deock; Bae, Seul Mi; Romilio, Anthony (2020-06-11). "Trackway evidence for large bipedal crocodylomorphs from the Cretaceous of Korea". Scientific Reports. 10 (1): 8680. Bibcode:2020NatSR..10.8680K. doi:10.1038/s41598-020-66008-7. ISSN   2045-2322. PMC   7289791 . PMID   32528068.
6. Sennikov, Andrey Gerasimovich (December 2021). "The Plantigrade Segnosaurians: Sloth Dinosaurs or Bear Dinosaurs?". Paleontological Journal. 55 (10): 1158–1185. doi:10.1134/S0031030121100087.
7. Witton, M.P. (2010). "Pteranodon and beyond: The history of giant pterosaurs from 1870 onwards". Geological Society London Special Publications. 343 (1): 313–323. Bibcode:2010GSLSP.343..313W. doi:10.1144/SP343.19. S2CID   128801077.
8. Kubo, T. (2011). "Estimating body weight from footprints: Application to pterosaurs". Cretaceous Research. 299 (1–2): 197–199. Bibcode:2011PPP...299..197K. doi:10.1016/j.palaeo.2010.11.001.
9. Witton, M. P. (2013). Pterosaurs: Natural History, Evolution, Anatomy (1st ed.). Princeton University Press. pp. 255–257. ISBN   978-0-691-15061-1.
10. Masrour, M.; de Ducla, M.; Billon-Bruyat, J.-P.; Mazin, J.-M. (2018). "Rediscovery of the Tagragra Tracksite (Maastrichtian, Agadir, Morocco): Agadirichnus elegans Ambroggi and Lapparent 1954 is Pterosaurian Ichnotaxon". Ichnos. 25 (4): 285–294. doi:10.1080/10420940.2017.1386661.
11. Xing, Lida; Díaz-Martínez, Ignacio; Lallensack, Jens N.; Kim, Kyung Soo; Buckley, Lisa G.; Romilio, Anthony; Piñuela, Laura; Wang, Donghao; Chen, Qiyan; Yang, Qing; Chou, Chunyong; Yin, Hang; Jin, Yufei (2025). "Cretaceous vertebrate tracks". Vertebrate Ichnology: 479–747. doi:10.1016/B978-0-443-13837-9.00002-0.