Pawsitively prehistoric

First described from Laos in 2005, the Laotian rock rat Laonastes aenigmamus quickly gained fame as one of the most remarkable “living fossil” discoveries in modern mammalogy.

A. Abramov (Zoological Institute RAS) with Laonastes aenigmamus in Laos in 2008

The Laotian rock rat is a small, nocturnal rodent inhabiting rugged karst landscapes (Jenkins et al. 2005; Nguyen et al. 2014). Its robust body, dense fur and long, squirrel-like tail reflect adaptation to a rocky, largely scansorial lifestyle. Despite its modest

appearance, Laonastes represents one of the most surprising zoological findings of recent

decades and has attracted broad interest from systematists and paleontologists.

Morphological and molecular data show that Laonastes is the only extant representative of the rodent family Diatomyidae, previously known exclusively from Oligocene – Miocene fossils and thought to have been extinct 11 million years (Jenkins et al. 2005; Dawson et al. 2006; Huchon et al. 2007). Laonastes is separated from the closest living rodent family by 44 million years. This unexpected survival of an ancient lineage — sometimes called the “Lazarus effect” — has made Laonastes a key taxon for understanding deep splits among rodent clades and the biogeographic history of Southeast Asia.

Today, we present a chromosome-length genome assembly of Laonastes aenigmamus (2n=36) from Vietnam, generated using a combination of long-read sequencing and Hi-C scaffolding. The assembly provides a crucial genomic resource for exploring the evolutionary history of Diatomyidae, testing hypotheses about cryptic species diversity within Laonastes, and examining patterns of genome conservation and rearrangement over tens of millions of years.

The data was generated from the fibroblast cell line LAON2m prepared from a tail sample of male Laonastes sp. collected in Thuong Hoa, Quang Binh, Vietnam, and provided by Alexey V. Abramov (Zoological Institute RAS).

References

• Dawson MR, Marivaux L, Li CK, Beard KC, Métais G. Laonastes and the "Lazarus effect" in recent mammals. Science. 2006 Mar 10;311(5766):1456-8. doi: 10.1126/science.1124187. PMID: 16527978.

• Huchon D, Chevret P, Jordan U, Kilpatrick CW, Ranwez V, Jenkins PD, Brosius J, Schmitz J. Multiple molecular evidences for a living mammalian fossil. Proc Natl Acad Sci U S A. 2007 May 1;104(18):7495-9. doi: 10.1073/pnas.0701289104. Epub 2007 Apr 23. PMID: 17452635; PMCID: PMC1863447.

• Jenkins PD, Kilpatrick CW, Robinson MF, Timmins RJ. (2005): Morphological and molecular investigations of a new family, genus and species of rodent (Mammalia: Rodentia: Hystricognatha) from Lao PDR. Systematics and Biodiversity 2(4): 419—454. doi:10.1017/S1477200004001549 (HTML abstract). Erratum: Systematics and Biodiversity 3(3):343. doi:10.1017/S1477200005001775

• Nguyen DX, Nguyen NX, Nguyen DD, Dinh TH, Le DT, Dinh DH. Distribution and habitat of the Laotian Rock Rat Laonastes aenigmamus Jenkins, Kilpatrick, Robinson & Timmins, 2005 (Rodentia: Diatomyidae) in Vietnam. Biodivers Data J. 2014 Dec 25;(2):e4188. doi:10.3897/BDJ.2.e4188. PMID: 25589873; PMCID: PMC4290499.

Life at the freezing edge

The fact that any small, cold blooded animal such as the insects can sustain temperatures below the freezing point of water has to be one of the most remarkable features of animal evolution. Even more impressive, the “snow fly” Chionea alexandriana is part of an elite group of insects that can maintain high levels of activity at sub-freezing temperature, and can often be spotted running on the snow-covered ground at temperatures between +3 and -5°C.

Image created by Sarah Becan for the Gallio Lab

To investigate the molecular adaptations that make this cold tolerance possible, we assembled the chromosome-length genome of the snow fly Chionea alexandriana. The assembly was created using a combination of PacBio HiFi and Hi-C sequencing from a a single male individual collected in the La Bohn Gap (47.55317, -121.24306). The work was supported in part by a grant from the Trienens Institute for Sustainability and Energy at Northwestern University (to Marco Gallio) and from the Crafoord foundation (to Marcus Stensmyr).

The analysis of the genome revealed several molecular adaptations including antifreeze proteins that prevent ice crystal formation, genetic pathways enabling cellular thermogenesis, and modifications to sensory and stress-response systems that enhance tolerance to extreme cold. You can read more about this work in

Capek M, Suhendra R, Yang Z, Omer AD, Weisz D, Dudchenko O, Tuthill J, Lieberman Aiden E, Kath WL, Para A, Stensmyr M and Gallio M. Coordinated molecular and physiological adaptations enable active behavior at subfreezing temperature in the snow fly Chionea alexandriana. Current Biology. 2026. https://doi.org/10.1016/j.cub.2026.02.060

Explore the interactive Hi-C contact map for the snow fly below, and check out the assembly page for more details and fasta links.

Furtress of solitude

In the Pilbara region of Western Australia lives the western pebble mouse (Pseudomys

chapmani), a rarely seen rodent that excavates a complex subterranean burrow system in the rocky substrate. These tunnels are topped with distinctive “fortress-style” pebble mounds composed of thousands of excavated pebbles that likely persist on this arid landscape for hundreds to thousands of years. Although their exact function remains unknown, they are thought to protect the mice from extreme desert conditions, including both intense heat and freezing temperatures.

Photo: A western pebble mound mouse (Pseudomys chapmani) next to a mound burrow entrance;

provided by Aline Gibson Vega.

Western pebble mice are typically solitary, however in the rare instances when outback conditions become hospitable during good years following major cyclonic activity, multiple females will live communally in a mound to cooperatively rear their offspring.

The western pebble mouse was only first discovered in 1980, 16 years after the first mines were established in the iron-rich Pilbara region. As mining activity has increased, so has the concern for this elusive species. Today, the Western Australian Department of Biodiversity, Conservation and Attractions declares the western pebble mouse to be a Priority 4 (taxa in need of monitoring) species.

Today, we release the chromosome-length genome of the western pebble mouse created using a combination of PacBio HiFi and Hi-C sequencing from a male sample collected at the Western Australian Museum.

This work was funded by an Australian Research Council to Renée Firman (University of Western Australia) and Dustin Rubenstein (Columbia University).

Explore the interactive Hi-C contact map for the western pebble mouse below, and check out the assembly page for more details and fasta links.