Collection Of Mammals Research Articles

Synonymy, redescription, molecular characterisation, and new distribution data of species of Stilestrongylus and Guerrerostrongylus (Nematoda, Heligmonellidae) parasitic in sigmodontine rodents from Argentina and Uruguay: a collection-based survey

In this study, we review the taxonomic status of the parasitic nematodes Stilestrongylus oryzomysi and Guerrerostrongylus uruguayensis (Heligmonellidae), which had been described only once from sigmodontine rodents from Argentina and Uruguay, respectively. To this aim, we examined 38 complete helminth sets deposited in the Helminthological Collection of the Museo de La Plata (MLP-He), Argentina, including type material of G. uruguayensis, S. oryzomysi, and a closely related species, Stilestrongylus azarai. We also examined voucher rodent specimens deposited in the Mammal Collection of the Museo de La Plata (MLP-Mz) to assess the identity of the symbiotypes and other rodent hosts. Based on these observations, S. oryzomysi is proposed as a junior synonym of S. azarai; the identity of the symbiotype of S. oryzomysi and Trichofreitasia lenti (Heligmonellidae) is emended from Oligoryzomys flavescens to Akodon azarae; G. uruguayensis is proposed as a junior synonym of Guerrerostrongylus zeta; S. azarai is redescribed based on type and voucher material; and the latter species and G. zeta are molecularly characterised using the ITS+ gene. We extend the geographic distribution of S. azarai to include Uruguay and provide a new host record for T. lenti (A. azarae, type host species), a new host record for G. zeta in Argentina (O. flavescens), and the first record of helminths for Oligoryzomys nigripes in Uruguay.

Article 74.7.3 of the Code continues to destabilise zoological nomenclature: repeated lectotypification of Lemmus obensis bungei (Rodentia: Cricetidae)

In 2023, B. Kryštufek and G.I. Shenbrot published a paper in which they proposed to consider invalid 20 lectotype designations based on the specimens in the collection of mammals at the Zoological Institute of the Russian Academy of Sciences (St Petersburg). They also designated a lectotype for Lemmus obensis bungei Vinogradov, 1926. We argue that the authors’ decision was based on an incorrect interpretation of Article 74.7.3 and some other Articles and Recommendations of the International Code of Zoological Nomenclature. The history of Article 74.7.3 is briefly reviewed to highlight its destabilising nature and to draw attention to this within the zootaxonomic community.

Updating the fauna and age of the Neogene-Quaternary large mammal sites of Greece

The Neogene-Quaternary continental deposits cover large areas of Greece and several fossil mammal sites have been discovered in the country. There are several collections of large fossil mammals for this time span, which provide important data for the fauna biochronology, correlations, palaeoecology and palaeogeography of the area. The last lists with the fauna, age and biochronology of the Greek large mammal localities were given in 2006 for the Neogene and in 2001 for the Quaternary. Extensive research over the last twenty years provided several new localities, and many data and information were published. Therefore, an updating of the lists was more than necessary, and the present article deals with it; it covers the time span untill June 2023. Lists include all faunal information as the systematic classification, chronology, biostratigraphic correlation of the faunas, and main bibliography. It is worth mentioning that some of the Greek localities are key-localities for the Eastern Mediterranean region, e.g., Pikermi, Axios Valley, Villafranchian collection. These faunas are important for the comparison and identification of new collections, correlations, palaeoecology, and palaeogeography of Neogene European mammals.

Bats (Mammalia: Chiroptera) from two priority areas for biodiversity conservation in the Brazilian Amazon and range extension for Carollia benkeithi (Phyllostomidae)

Abstract Amazonian tropical forests host the highest bat diversity in South America. The central area Brazilian Amazon encompasses one of the largest pristine areas within this biome, where Amanã and Mamirauá Sustainable Development Reserves (SDRs) are located. These two reserves hold the status of Priority Areas for Biodiversity Conservation due to their high biological relevance. The aim of this study was to identify the bat species richness within these SDRs to minimize the Wallacean shortfall of the chiropterofauna in the Amazon. A total of 274 specimens, collected 20 years ago and housed in the mammal collection at the Museu Paraense Emílio Goeldi, were sorted and identified. They are distributed across four families, 18 genera, and 26 species: Artibeus planirostris and Carollia perspicillata were the most abundant vouchers. We identified a range extension for Carollia benkeithi and a possible new taxon for the genus Micronycteris.

New record of Myotis ciliolabrum (Merriam, 1886) (Mammalia, Chiroptera) from the State of Mexico, Mexico

Myotis ciliolabrum (Merriam, 1886) is an insectivorous bat of the family Vespertilionidae and has a wide distribution from British Columbia, Alberta, and Saskatchewan in Canada, most of the western and central United States of America to central Mexico. In this study, we report one of the southernmost records from State of Mexico, based on two females collected in 1980 and stored in the Mammals Collection of the Universidad Autonóma Metropolitana. These records increases the knowledge on the distribution of this rare bat in Mexico.

Олег Яценя — натураліст, колектор, таксидерміст

An essay about a researcher from Kyiv who was a naturalist, traveller, collector, museum worker, and was interested in all manifestations of nature. As an employee of both the Zoological Museum of Kyiv University and the academic zoological museum, he collected materials in Kyiv, Cherkasy, Odesa, Crimea, Azerbaijan (especially Lankaran), and Turkmenistan (Kushka et al.) His mammal collections relate to different groups of micromammals, and in general he collected materials on all possible vertebrate groups. The researcher has only a few scientific works, and he was more interested in naturalism: collecting, hunting, aquarium, clubs, and youth naturalist groups.

Юрій Прожига — колектор зоологічних колекцій

An essay about a researcher who made a significant contribution to the formation of zoological collections and faunal research in Zhytomyr and Kyiv zoological centres. Yuriy Prozhyha collected numerous specimens of mammals, birds, and insects in various locations, primarily in the vicinity of Zhytomyr and several districts of Zhytomyr region (1914–1922, 1929–1932), as well as in Kyiv (1928) and Uzbekistan (1929). His mammal collections include 116 osteological specimens housed in the Paleontological Department of NMNH, NAS of Ukraine. He also wrote two articles on beavers (1928, 1929) and a book on plant protection from pests (1931).

Mammalian type material from Cameroon in the Museum für Naturkunde Berlin

Historical data, combined with current data on species distribution, are a valuable resource for tracking changes in biodiversity and can potentially be applied to developing models in conservation biology and designing and assessing conservation strategies. Historical data supporting current knowledge on the natural history of the African continent are primarily held in Western museums. The Zoologisches Museum Berlin (ZMB), which is today part of the Museum für Naturkunde Berlin (MfN), is the primary source of reference for zoological collections from former German colonial territories including Cameroon. Here, we document for the first time a catalogue of the type material in the mammal collection of the MfN from the point of view of a geographical region. The type collection includes 91 type specimens identified in the catalogues as originating from German ‘Kamerun’ and which correspond to 31 described species, of which 12 are currently accepted (valid) species names. Of the 31 described species, 21 are represented by holotypes, three para-holotype series, one para-lectotype series and six syntype series. We hope that this first analysis of zoological objects, based on geographical location, will lead to similar research on other geographical locations of collection. This could provide more information on the provenance of collections and on colonial collecting practices, as well as contribute to the accessibility of collections in Western museums.

Колекції Миколи Дюкова та Віктора Дребенцова у Національному науково-природничому музеї (Київ)

The history of collections that became part of the academic zoological collection prior to the Second World War and which is now being housed in the National Museum of Natural History (NMNH), NAS of Ukraine was studied. The specimens in this collection had probably been kept in zoological centres of Kharkiv before. The collected specimens and their label data are considered as an important source for an entire series of reconstructions, such as the history of species, the history of research, the biographies of researchers, and the history of collections and museums. Along with bibliographic search and mentions of finds of species and their collectors, such data are promising for the reconstruction of important pages in the history of scientific research and scientific institutions. All such approaches were used to investigate the history of research related to the names of Mykola Diukov and Viktor Drebentsov (Drebentsiv) — two researchers who were not included in the list of the hundred most famous mammalogists of Ukraine (review of 2022), but turned out to be iconic persons. Their scientific careers turned out to be closely related to the Kharkiv plant protection centres, and both researchers carried out active research and collection work in the Kharkiv region and in a number of southern regions of Ukraine in the 1920s and early 1930s. The destinies of both of researchers took sharp turns during the period of Stalinist repressions in Ukraine (Union for the Freedom of Ukraine trial, Holodomor, political purges, etc.), and both left not only Kharkiv, but also Ukraine: Diukov ended up in Dagestan working in the plant protection system, whereas Drebentsov in Murmansk at the polar institute, and later in the regional museum of local history. In the new places, the researchers continued their zoological practices, collecting and organizing collections of vertebrate animals (mainly mammals and birds) and achieved a high level of recognition: Diukov became one of the key zoologists and nature popularisers in Dagestan, and so did Drebentsov in Murman. Their destinies turned out differently: M. Diukov was eventually repressed (spent five years in concentration camps) and went missing, whereas V. Drebentsov became a recipient of various state awards. The names of both researchers should be included in the registers of zoologists who formed the foundations of modern knowledge and collections. The authors associate the preservation and transfer of their collections with the activities of O. Myhulin, who in 1938 published the monograph “Mammals of the Ukrainian SSR”, which is largely based on the analysis of mammal collections.

Pleistocene South American native ungulates (Notoungulata and Litopterna) of the historical Roth collections in Switzerland, from the Pampean Region of Argentina

The fossil collections made by early explorers in South America have been fundamental to reveal the past diversity of extinct mammals and unravel their evolutionary history. One important early explorer in South America was the Swiss-Argentine palaeontologist Kaspar Jacob Roth, known as Santiago Roth (1850, Herisau, Switzerland-1924, Buenos Aires, Argentina), who made significant collections of fossil mammals that are housed in museums in Europe and Argentina. The important collections of Roth in Switzerland include iconic Pleistocene megafauna from the Pampean Region (Argentina). The palaeontological significance of the Pampean Region relies on its abundant record of fossil vertebrates that documents diversity dynamics and paleoenvironmental change in southern South America, serving as the basis for the South American biostratigraphical scale of the late Neogene and Quaternary. The South American native ungulates (SANUs) were hoofed placental mammals that radiated in South America. The clades Notoungulata and Litopterna include, among others, the last representatives of SANUs megafauna in the continent. We revise and describe for the first time the SANUs specimens from the Pampean Region of the Roth collections in Switzerland. The collections include two species of notoungulates (Toxodon cf. T. platensis and Mesotherium cristatum) and one litoptern species (Macrauchenia patachonica). The occurrences are restricted to the early and middle Pleistocene (pre-Lujanian Stages/Ages). Although the SANUs diversity in the Roth collections is low in comparison with other groups (e.g., xenarthrans), some of the specimens are very complete, including skulls and postcranial remains. The completeness of the Ma. patachonica material allows an update and reinterpretation of some of the details of the dentition and the postcranial skeleton of this iconic species. In addition to its historical importance, the SANU specimens from the Roth collections provide important information to study the paleobiology and evolution of South American megafauna and evaluate hypotheses about their extinction in the continent.

Long-Read Sequencing Reveals Rapid Evolution of Immunity- and Cancer-Related Genes in Bats.

Bats are exceptional among mammals for their powered flight, extended lifespans, and robust immune systems and therefore have been of particular interest in comparative genomics. Using the Oxford Nanopore Technologies long-read platform, we sequenced the genomes of two bat species with key phylogenetic positions, the Jamaican fruit bat (Artibeus jamaicensis) and the Mesoamerican mustached bat (Pteronotus mesoamericanus), and carried out a comprehensive comparative genomic analysis with a diverse collection of bats and other mammals. The high-quality, long-read genome assemblies revealed a contraction of interferon (IFN)-α at the immunity-related type I IFN locus in bats, resulting in a shift in relative IFN-ω and IFN-α copy numbers. Contradicting previous hypotheses of constitutive expression of IFN-α being a feature of the bat immune system, three bat species lost all IFN-α genes. This shift to IFN-ω could contribute to the increased viral tolerance that has made bats a common reservoir for viruses that can be transmitted to humans. Antiviral genes stimulated by type I IFNs also showed evidence of rapid evolution, including a lineage-specific duplication of IFN-induced transmembrane genes and positive selection in IFIT2. In addition, 33 tumor suppressors and 6 DNA-repair genes showed signs of positive selection, perhaps contributing to increased longevity and reduced cancer rates in bats. The robust immune systems of bats rely on both bat-wide and lineage-specific evolution in the immune gene repertoire, suggesting diverse immune strategies. Our study provides new genomic resources for bats and sheds new light on the extraordinary molecular evolution in this critically important group of mammals.

Classifying Colonial Objects in Museum Collections with Machine Learning and Historical Knowledge

Many natural history collections and museums in Europe were established in the late 18th and early 19th century. Their development is inseparably linked to colonial expansion and significant parts of their collections are of colonial origin. The Museum für Naturkunde Berlin (MfN) preserves a large natural history collection comprising zoological, paleontological, mineralogical, geological, and botanical objects as well as an institutional archive and a library. Especially in the period from 1884 to 1919, when the German Reich had colonies in Africa, the Pacific and China, the Zoological Museum of today's MfN played a prominent role in imperial politics. By a decision of the Federal Council in 1889 (Bundesratsbeschluss) and an addendum to this resolution in 1891, the museum received all zoological objects from expeditions financed by the state as well as the materials collected by colonial officials (Anonymous 1890,Kaiser 2023). The disclosure and digital transformation of museum collections worldwide will significantly improve digital access for all stakeholders. Opening up the (digital) collections is also considered crucial for the role of museums in mobilising participation and societal change. However, the mere size of the MfN collection, estimated to comprise approximately 30 million objects, poses additional challenges. How can we identify the objects from colonial contexts among these millions and how do we tag them? A recent project, "Colonial Provences of Nature",*1 led by historians at MfN, designed a decision tree to identify collection objects from the colonial past in which relevant categories of information and critical metadata were determined to confirm a colonial acquisition context (Kaiser et al. 2023). In this talk we will present our approach and preliminary results towards automatisation of the decision-making process in the mammals collection at MfN. This subcollection offers a suitable case study for testing how machine learning algorithms and historical knowledge can be used to classify colonial items based on their geographical provenance and acquisition time. Several specimens were indeed acquired during German colonial rule in Africa, Asia and Oceania between the 1880s and the end of World War I. The metadata associated with these objects are available in the institutional collection management system and they can be extracted and cleaned to generate a dataset for training and testing decision trees (Alpaydin 2020). The research of suitable classifying algorithms has a dual scope. The first is to compare the algorithmic decision boundaries with the rule-based decision tree drawn by the MfN historians interested in identifying and tagging collection objects from colonial contexts. The second aim is to develop automated procedures for labelling objects in the museum collections as colonial/non-colonial and add this information to the standard taxonomic metadata raising awareness on the complex political history of the specimens available at MfN.

Identification of species of the genus Sylvaemus of northeastern Ukraine by metric characters

The reliable identification of representatives of the genus Sylvaemus is compli-cated by the huge coincidence of external and metrical characters, as well as by the fact that in most of their range, mice are in conditions of sympatry or even syntopy Moreover, identification is complicated by opposite clinal variability in size and geographic variability in fur colouration. The species are also similar in karyotypes, so their reliable identification is usually possible only based on biochemical or molecular analysis. The craniological collection of small mam-mals of O. V. Zorya and collection specimens of the Museum of Nature of V. N. Karazin Kharkiv National University were studied. In total, 436 speci-mens of three species of the genus Sylvaemus were analysed: Sylvaemus ura-lensis, Sylvaemus sylvaticus, and Sylvaemus tauricus. Analysed were 14 odon-tometric and 23 craniological characters. Among the metric characters, three odontometrical—width of first upper molar (WM1), length of second lower molar (LM2), length of lower molar row (LM123)—and seven craniometrical characters—length of first upper molar (LM1), length of foramen incisivum (LFI), length of upper molar row (LUM), width of choana (WCH), height of skull including bulla tympanica (HBCB), length of lower molar row (LLM), length of mandible (LM)—made the greatest contribution to the differentiation of mice of the genus Sylvaemus. Width of first upper molar (WM1), length of first lower molar (LM1), length of second lower molar (LM2), length of brain-case (LBC), least interorbital constriction (LIOC), width of braincase (WBC), distance between incisor and M3 (LIM3), length of upper molar row (LUM), condylobasal length of skull (CBL), palatal length (LPP), greatest length of skull (GLS), and length of lower molar row (LLM) are the least variable metric char-acters. Scatterplots linking LLM/CBL, LUM/CBL, and LUM/GLS appeared to be the most suitable for differentiating the specimens, with minimal overlap of species in the morphospace. In north-eastern Ukraine, the best distribution of mice of the genus Sylvaemus was obtained as a result of the analysis based on both odontometrical and craniological characters, when the correctness of the classification was 100%.

Notes on mammals collected on the 1885 Geographical Society of Australasia’s Expedition to New Guinea

In 1885 the Geographical Society of Australasia sent the steam launch Bonito to chart the Fly and Strickland Rivers (now in Western Province, Papua New Guinea). The Expedition spent five months in New Guinea with the primary objectives of survey and biological exploration. The type locality of the murid rodent Melomys muscalis froggatti Troughton, 1937, described from a single specimen obtained during the Expedition, is localized to the region of the base camp at Observation Bend, Strickland River, based on the original Expedition maps and the unpublished diary reminiscence of the collector W. W. Froggatt. A review of the mammal collection obtained during that Expedition has not been reported previously, perhaps due to the poor surviving documentation. Several months after the Expedition returned to Sydney, Australian Museum curator E. P. Ramsay prepared a list of 22 mammal specimens received by the Museum. Twenty specimens attributed to the Expedition were not entered into the collection registers until 1913, half of which are likely to be incorrectly associated with the Expedition. Most specimens were registered with very limited data about collection date and locality. Of the 22 specimens originally received by Ramsay, eight rodents and two flying foxes (Pteropus spp.) have not been located in the Collection, but might remain unrecognized as specimens with no data. It is possible that additional mammal specimens were sent by the Geographical Society of Australasia to other institutions at the conclusion of the Expedition.

Arctic Quaternary Mammal Collections in the Museums of Yakutsk (Yakutia, East Siberia, Russia)

Many Ice Age fossil mammals remains are found in Yakutia, which occupies most of Eastern Siberia. In the city of Yakutsk, various museum and scientific institutions hold collections and exhibits of Quaternary mammals collected at different times in different locations in the Arctic zone of Yakutia. These collections mostly represents the Late Pleistocene Mammoth Fauna, and are housed in the Emelyan Yarosslavsky’s Yakutsk State Museum of History and Culture of the Peoples of the North, the Mammoth Museum, the Geological Museum of Diamond and Precious Metals Geology Institute, Siberian Branch of Russian Academy of Sciences, and the Department of the Mammoth Fauna study, Academy of Sciences of the Sakha (Yakutia) Republic. These collections include woolly mammoth skeletons, other fragments of mammoths, woolly rhinoceros and horse carcasses, whole carcasses of steppe bison, cave lion cubs, and other fossil mammals, many bones and teeth of various mammals of the Mammoth Fauna. The study of these fossil mammal remains allow identification of features of their anatomy and morphology, as well as reconstruction of the ecological conditions at the time they were alive.

Checklist of the Mammal Collection Preserved at the University of Palermo under the Framework of the National Biodiversity Future Center

The latest reorganization of the Vertebrate collections preserved at the “Pietro Doderlein” Museum of Zoology of the University of Palermo (Italy) has made it possible to draw up a check-list of the Mammal taxa present in the stuffed (M), fluid-preserved (ML) and anatomical (AN) collections. The intervention was planned under the National Biodiversity Future Center (NBFC) agenda, focused on the enhancement of Italian natural history museums. The growing interest in museum collections strongly demands databases available to the academic and policy world. In this paper, we record 679 specimens belonging to 157 specific taxa arranged in 58 families and 16 orders. Most of the species (75.1%) come from the Palaearctic Region (southern Mediterranean and North Africa), with a minority of taxa coming from the Afrotropical (7.8%), Neotropical (4.6%), Indo-Malayan (3.4%) and Australasian (1%) regions. Among the 24% of the taxa listed in the IUCN categories as threatened (VU, EN, CR, RE) the specimens of the Sicilian wolf, a regional endemic subspecies that became extinct in the last century, stand out. Even if small (<1000 specimens), the collection of mammals of the Museum of Zoology is an important asset for research on biodiversity in the Mediterranean area, representing an international reference for those wishing to conduct morphological and genetic studies in this area.

Xenarthrans of the collection of Santiago Roth from the Pampean Region of Argentina (Pleistocene), in Zurich, Switzerland

The present work concerns xenarthrans from the collection of Santiago (Kaspar Jakob) Roth (1850–1924) housed at the Palaeontological Institute and Museum of the University of Zurich, one of the most important collections of Pleistocene mammals from Argentina in Europe. Roth was a paleontologist originally from Switzerland who prospected and collected a large amount of Pleistocene megafauna of the Pampean Region of Argentina. The xenarthrans are the main representatives of this collection in Zurich, with 150 specimens. Since 1920, this material has not been revised and is under studied. The present investigation corresponds to a taxonomic revision resulting in 114 reassignments, leading to document xenarthran diversity and discuss their paleoecologies. The high diversity reflects the paleoecology of the Pampean Region during the Pleistocene, with the various abiotic events that impacted the paleoenvironment of this region. Within the Cingulata, the Pampean Region fauna was probably dominated by glyptodonts with a high representation of Glyptodontinae and Neosclerocalyptinae while within the sloths the highest diversity and abundance is found in the Mylodontinae and Scelidotheriinae. These four clades represent both species with high ecological tolerance (e.g., Glyptodon munizi; Catonyx tarijensis) and ecologically highly specialized species (e.g., Neosclerocalyptus paskoensis; Scelidotherium leptocephalum). The presence of such ecological diversity underlines the status of the Pampean Region as a major interest for paleoecological and paleoenvironmental reconstruction.

The name-bearing type is essential for the objective identification of a taxonomic name: the message from the lectotypification of Lemmus obensis bungei

Abstract We looked at lectotype designations by Baranova and Gromov from among syntypes in the Mammal Collection of the Zoological Institute of the Russian Academy of Sciences (ZIN) in St. Petersburg, Russia. We identified 20 lectotypifications, published in 2003, which do not accord to Articles 74.7.3 and/or 74.1.3 of the Code and are therefore invalid. Particularly instructive is the case of Lemmus obensis bungei Vinogradov, B.S. (1924). Two new interesting lemmings from Siberia. Ann. Mag. Nat. Hist. 9: 186–188, since its syntypes originated from two allopatric phylogenetic lineages which were classified as distinct nominal taxa. Because the act of lectotypification by Baranova and Gromov does not contain an express statement of deliberate designation as is requested by the amended Article 74.7.3 of the Code, their designation is not valid. To secure the nomenclatural stability of Siberian lemmings we designate voucher ZIN 11,025 (skin and skull from Sagastyr Island) as the lectotype of Lemmus obensis bungei. The name bungei thus defined is a junior synonym of Lemmus lemmus sibiricus (Kerr, R. (1792). The animal kingdom […] of the celebrated Sir Charles Linnæus. Class I. Mammalia, J. Murray, London) with a range at the shores of the Arctic Ocean, between the Northern Dvina and Lena Rivers. We furthermore provide a list of all invalid lectotypifications of hamsters (Cricetinae) and voles (Arvicolinae) based on ZIN syntypes.

Tasmanian bandicoots as fungal dispersers: A comparison in mycophagy between the southern brown bandicoot (Isoodon obesulus) and the eastern barred bandicoot (Perameles gunnii)

Mycophagous mammals perform important ecosystem services through their dispersal of mycorrhizal fungi (particularly truffles). In order to better understand the role of Tasmanian bandicoots in these associations, we examined the stomach and scat contents of specimens of southern brown bandicoots (Isoodon obesulus) and eastern barred bandicoots (Perameles gunnii) preserved in the mammal collections of the Queen Victoria Museum and Art Gallery. Our study shows that fungi are consumed by both species and that these mammals likely play a key role in ecosystem function through their dispersal of mycorrhizal fungal spores.

Determination of age in representatives of the genus Sylvaemus by the degree of molar wear

Various methods are used to identify representatives of the genus Sylvaemus, most of which are metric. In order to exclude anomalies in further calculations and to minimize allometric variations associated with the growth of animals, it is necessary to take into account age as an important factor of variability. Usually, a number of criteria are used to determine the age and describe the growth of mice: measurements of body and skull parameters, body weight, the degree molar wear, and the weight of the lens of the eye. Length is a more consistent guide for determining the age of mice than body weight, which usually ceases to be directly related to age after reaching adult size. Age can also be determined by the fusion of the epiphysis with the diaphysis in the bones of the limbs and by the degree of development of the thymus. Most often, teeth are used to determine age. Among such age criteria, we distinguish eruption and replacement of teeth sets, tooth growth in length, overgrowth of the tooth pulp cavity, tooth wear, and annual layers in the tooth tissues. Usually, the age of mice is determined by the degree of molar wear. Some authors do not consider this method universal due to individual feeding habits of animals and other environmental factors. The order of wear of tooth rows can sometimes change, and the degree of wear of the right and left tooth rows can also differ. The craniological collection of small mammals of O. V. Zorya, collected in the territory of Kharkiv Oblast, Ukraine, was studied. In total, 198 specimens of three species of the genus Sylvaemus were analysed: Sylvaemus uralensis, Sylvaemus sylvaticus, and Sylvaemus tauricus. Analysed were 14 odontometric and 23 craniological characters. Among the metric characters, four odontometric (LM2, WM1, LM2, LM123) and nine craniological characters (LIOC, LD, LFI, LPP, WCH, GLS, DI, LLM, LM) made the greatest contribution to the age group differentiation of mice of the genus Sylvaemus. Among the features that contributed the most to the differentiation, length measurements prevailed. LLM, LM123, LPP, LIOC, and GLS are the least variable metric characters. It is not possible to divide the sample of mice of the genus Sylvaemus into age groups based on odontometric and craniological character since the ranges of values of metric characters overlap.