Ornithorhynchoidea

Ornithorhynchoids Temporal range: Late Cretaceous (Cenomanian)–present PreꞒ Ꞓ O S D C P T J K Pg N
Two extant ornithorhynchoids: the short-beaked echidna (above) and platypus (below)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Monotremata
Superfamily:	Ornithorhynchoidea Flannery et al., 2024
Families
† Opalionidae Ornithorhynchidae Tachyglossidae
Range of extant ornithorhynchoids

Ornithorhynchoidea is a superfamily of egg-laying mammals containing the only living monotremes, the platypus and the echidnas, as well as their closest fossil relatives, to the exclusion of more primitive fossil monotremes of uncertain affinity. ^[1]

The clade was defined in 2024 following the discovery of some fossil monotremes from the Late Cretaceous (Cenomanian)-aged Griman Creek Formation of Lightning Ridge Australia, which appeared to be more closely related to extant monotremes than to co-occurring early monotremes such as Steropodon and Kollikodon . ^{[1] [2]}

Taxonomy

Opalios , the only described member of the extinct family Opalionidae, is considered the most basal ornithorhynchoid due to its unique combination of ancestral and derived traits. ^[1]

The presence of the probable stem-ornithorhynchids Dharragarra and Patagorhynchus in the Late Cretaceous implies that the divergence between the platypus and echidnas may have occurred during this time. ^[1] However, genetic estimates tend to prefer a Cenozoic divergence between these two extant groups. ^{[3] [4]}

Although most members of this group—extinct and extant—are known from Australia, at least two ornithorhynchid-like forms reached southern South America during the Maastrichtian (Patagorhynchus) and early Paleocene ( Monotrematum ). ^{[5] [6]}

The following genera are known:

• Superfamily Ornithorhynchoidea Flannery et al., 2024
  • Family † Opalionidae Flannery et al., 2024
    • Genus † Opalios Flannery et al., 2024
  • Family Ornithorhynchidae Gray, 1825
    • Genus ?† Dharragarra Flannery et al., 2024
    • Genus ?† Monotrematum Pascual et al., 1992
    • Genus † Obdurodon Woodburne & Tedford, 1975
    • Genus ?† Patagorhynchus Chimento et al., 2023
    • Genus Ornithorhynchus Blumenbach, 1800
  • Family Tachyglossidae Gill, 1872
    • Genus † Megalibgwilia Griffiths, Wells & Barrie, 1991
    • Genus † Murrayglossus Flannery et al., 2022
    • Genus Tachyglossus Illiger, 1811
    • Genus Zaglossus Gill, 1877

They can be distinguished from other fossil monotremes by their twisted-shaped dentaries, with the lingual surfaces being dorsoventrally flattened (aside from in echidnas). ^[1]

References

1. Flannery, Timothy F.; McCurry, Matthew R.; Rich, Thomas H.; Vickers-Rich, Patricia; Smith, Elizabeth T.; Helgen, Kristofer M. (2024-05-26). "A diverse assemblage of monotremes (Monotremata) from the Cenomanian Lightning Ridge fauna of New South Wales, Australia". Alcheringa: An Australasian Journal of Palaeontology . 48 (2): 319–337. Bibcode:2024Alch...48..319F. doi: 10.1080/03115518.2024.2348753 . ISSN   0311-5518.
2. de Kruijff, Peter (2024-05-26). "'Echidnapus' fossil of potential echidna and platypus ancestor may point to Australian 'age of monotremes'". ABC News . Archived from the original on 2024-05-27. Retrieved 2024-05-27.
3. Phillips MJ, Bennett TH, Lee MS (October 2009). "Molecules, morphology, and ecology indicate a recent, amphibious ancestry for echidnas". Proceedings of the National Academy of Sciences of the United States of America. 106 (40): 17089–94. Bibcode:2009PNAS..10617089P. doi: 10.1073/pnas.0904649106 . PMC   2761324 . PMID   19805098.
4. Zhou, Yang; Shearwin-Whyatt, Linda; Li, Jing; Song, Zhenzhen; Hayakawa, Takashi; Stevens, David; Fenelon, Jane C.; Peel, Emma; Cheng, Yuanyuan; Pajpach, Filip; Bradley, Natasha; Suzuki, Hikoyu; Nikaido, Masato; Damas, Joana; Daish, Tasman (2021-04-06). "Platypus and echidna genomes reveal mammalian biology and evolution". Nature. 592 (7856): 756–762. Bibcode:2021Natur.592..756Z. doi:10.1038/s41586-020-03039-0. hdl: 2440/130050 . ISSN   1476-4687. PMC   8081666 . PMID   33408411.
5. Flannery, Timothy F.; Rich, Thomas H.; Vickers-Rich, Patricia; Ziegler, Tim; Veatch, E. Grace; Helgen, Kristofer M. (2022-01-02). "A review of monotreme (Monotremata) evolution". Alcheringa: An Australasian Journal of Palaeontology . 46 (1): 3–20. Bibcode:2022Alch...46....3F. doi: 10.1080/03115518.2022.2025900 . ISSN   0311-5518.
6. Chimento, Nicolás R.; Agnolín, Federico L.; Manabe, Makoto; Tsuihiji, Takanobu; Rich, Thomas H.; Vickers-Rich, Patricia; Novas, Fernando E. (2023-02-16). "First monotreme from the Late Cretaceous of South America". Communications Biology. 6 (1): 146. doi:10.1038/s42003-023-04498-7. ISSN   2399-3642. PMC   9935847 . PMID   36797304.