The shrew opossums (Order Paucituberculata, infraclass Marsupialia) are small, shrew-like animals that live in South America. Only 3 genera, in one family, are known (Encyclopædia Britannica).
The most extensive recent work on the evolution of marsupials is the study by Beck et al (2022) that combines molecular data and craniodental morphological characters. The latter were taken solely from the cranium, mandible, and dentition because most of the fossil taxa are represented only by such craniodental material.
The phylogenetic analysis of the study by Beck et al (2022) is the basis for the following phylogenetic time tree:
The most extensive recent work on the evolution of marsupials is the study by Beck et al (2022) that combines molecular data and craniodental morphological characters. The latter were taken solely from the cranium, mandible, and dentition because most of the fossil taxa are represented only by such craniodental material.
The phylogenetic analysis of the study by Beck et al (2022) is the basis for the following phylogenetic time tree:
Figure 1. Time tree of the stem-Paucituberculata
The oldest known member of the stem-Paucituberculata is Evolestes sp., described from the Early Oligocene Unit 3 of the Upper Puesto Almendra Member of the Sarmiento Formation at site GBV-19 (“La Cantera” locality), Gran Barranca south of Lake Colhue-Huapi, Sarmiento Department, Chubut Province, Argentina (Beck et al, 2022). No images are available in the public domain, but several other members of the stem group are illustrated below (for a larger view, click on image):
Figure 2. Images of stem-Paucituberculata
The above images are ordered from most basal to most crownward, but there are too few of them to allow evolutionary trends to be suggested.
No fossils are known from the crown group of the Paucituberculata.
No fossils are known from the crown group of the Paucituberculata.
Reference
Beck, R. M., Voss, R. S., & Jansa, S. A. (2022). Craniodental morphology and phylogeny of marsupials. Bulletin of the American Museum of Natural History, 457(1), 1-352.
Image credits – stem-Paucituberculata
- Header (Grey-bellied shrew opossum, Caenolestes caniventer): jorgebrito, CC0, via Wikimedia Commons
- Figure 2 (Yalkaparidon coheni): Open Access article Archer, M., Beck, R., Gott, M., Hand, S., Godthelp, H., & Black, K. (2011). Australia's first fossil marsupial mole (Notoryctemorphia) resolves controversies about their evolution and palaeoenvironmental origins. Proceedings of the Royal Society B: Biological Sciences, 278(1711), 1498.
- Figure 2 (Stilotherium dissimile): Robert Bruce Horsfall, Public domain, via Wikimedia Commons
- Figure 2 (Acdestis oweni): Open Access article Chornogubsky Clerici, L., Abello, M. A., & Barmak, G. D. (2019). The Metatheria from the Río Santa Cruz (Santa Cruz Formation, Early-Middle Miocene, Argentina): History and new records.
- Figure 2 (Palaeothentes spp.): Open Access article Chornogubsky Clerici, L., Abello, M. A., & Barmak, G. D. (2019). The Metatheria from the Río Santa Cruz (Santa Cruz Formation, Early-Middle Miocene, Argentina): History and new records.