Search

Trogontherium minus Newton, 1890 (Figs 4-6) MATERIAL EXAMINED. — Left mandibular fragment with incisor to m2 (IPB-HaR-5642), right maxillary fragment with P4 to M2 (IPB-HaR-5643). Isolated teeth: left dP4 (IPB-HaR-5650), left P4 (IPB-HaR-5645), right P4 (IPB-HaR-5649), right M1/2 (IPB- HaR-5652), left M1/2 (IPB-HaR-5646 and IPB-HaR-5647), right M3 (IPB-HaR-5644 and IPB-HaR-5651), left M3 (IPB- HaR-5648) and incisor fragment (IPB-HaR-5654). MEASUREMENTS. — See Table 2. DESCRIPTIONS i – HaR-5642 (Fig. 4) The specimen exhibits the only complete incisor presented here despite several fragments also being found. The rounded enamel band is finely wrinkled but does not show longitudinal grooves. The wear facet is slightly curved and runs from the tip of the incisor to the lower jaw symphysis. m1/2 – HaR- 5642 m 1 and HaR- 5642 m 2 (Fig. 4) The hypostriid reaches the base of the exposed tooth. No cement is in the striids. The anterior half of the tooth is higher than the posterior half. The paraflexid is curving anteriorly. The hypoflexid and mesoflexid seem to be “face to face” and meet at the middle of the tooth. The mesoflexid is horizontal and the hypoflexid seems to be oriented posteriorly. The metaflexid is oriented anteriorly. The rectangular shaped m1 is slightly worn. The tooth is dipping anteriorly (Fig. 4A, C). The labial side is shorter than the lingual. The entire height of the striids is exposed. The hypostriid closes at the end of the exposed tooth. There is no cement in the striids. The hypoflexid is curving posteriorly. The metaflexid is horizontal and reaches the middle of the tooth. The mesoflexid is short, slightly curving anteriorly. The paraflexid is curving anteriorly, almost reaching the anterior wall. The m2 is slightly worn. There is no cement in the striids. The tooth morphology identical with the m1. p4 – HaR-5642 (Fig. 4) The p4 is erupting. It has not reached the occlusal surface yet and is therefore completely unworn. There is no cement in the striids. The hypostriid reaches the base of the exposed tooth. The anterior half is higher than the posterior half. The paraflexid is curving anteriorly. The hypoflexid and mesoflexid seem to be “face to face” and meet at mid-length of the tooth. The mesoflexid is horizontal to the width and the hypoflexid seems to be oriented posteriorly. The metaflexid is oriented anteriorly. I – HaR-5654 (Fig. 5A) The figured incisor fragment shows the characteristic crenulations and the longitudinal lines. The other incisor fragments from this site which are not figured, also show these features although not as clearly as in this one. All fragments show a convex surface. dP4 – HaR-5650 (Fig. 5B) This medium worn tooth is very low crowned. The shape is close to triangular, although quite rounded. The anterior and posterior sides are rounded and the anterior one is wider. The parastria and the mesostria span the whole preserved height of the tooth, the metastria is almost worn off. The hypostria is longer than the others but does not reach the base of the tooth crown. The paraflexus is facing the hypoflexus although the hypoflexus ends slightly more anteriorly. The mesoflexus is open on both sides of the tooth and creates an indentation on the labial side. The metaflexus is curving anteriorly before dipping posteriorly (with a smaller angle). P4 – HaR-5643, HaR-5645 and HaR-5649 (Fig. 5 C-G) The three teeth are heavily worn with the hypoflexus closing. HaR-5643 is preserved in a bone fragment with two other teeth (Fig. 5 C-E). Shape is triangular, the anterior side is rounded and the labial side shorter than the lingual side. The hypostria is the only remaining stria. There is no cement in the fossettes nor the hypoflexus. The enamel of HaR-5649 (Fig. 5G) is wrinkled, which is more strongly visible on its antero-lingual side. The hypoflexus meets the parafossette. It is oriented anteriorly on HaR-5645 (Fig. 5F) and rather straight on HaR-5643 and HaR-5649. On this tooth the fossettes are also rather straight whereas they are more curved on HaR-5645. Both metafossette and mesofossette are parallel to the anterior wall except on HaR-5643 where they are tilting postero-labially. They are touching the outer walls of the tooth. The fossettes and the hypoflexus are more or less parallel to each other’s. The enamel of the anterior wall, on the posterior side of the fossettes and of the hypoflexus are thicker. On HaR-5645 and HaR-5649, the posterior root is broken off (Fig. 5F 1; G 1). M 1/2 – HaR-5643, HaR-5646, HaR-5647 and HaR-5652 (Figs 5 C-E; 6A-C) HaR-5643 (M 1 and M 2, Fig. 5 C-E), HaR-5646 (Fig. 6A) and 5647 (Fig. 6B) are heavily worn. On HaR-5643 and HaR-5647, the hypoflexus is not fully closed yet and the hypostria is still visible on HaR-5643 although shorter on the M 2 than on the M. HaR-5652 (Fig. 6C) is only slightly worn and is the only specimen still retaining striae. The parastria is really short and the mesostria a little longer. The metastria is not observable. On this specimen the hypostria is quite long, although not reaching the base of the tooth. Due to the early wear stage, this tooth still has a relatively triangular shape with a rounded anterior side, wider than the posterior side. The postero-buccal face, below the occlusal surface is damaged. The shape of the other four teeth is close to square with the anterior side rounded and the labial side shorter than the lingual. On HaR-5646 and 5647, the parafossette and the metafossette are small, although smaller on HaR-5647. They are also really small on the M 1 and M 2 on HaR-5643. The hypofossette touches the parafossette. The fossettes are more or less parallel to the anterior side. On HaR-5643, the fossettes are titling postero-lingually and more or less parallel to the hypoflexus. On these teeth, the hypoflexus is going anteriorly and meeting the parafossette. The parafossette and metafossette of the M 2 on HaR-5643 are bigger than in the M 1 and hence, the hypoflexus is shorter. The metafossette of HaR-5647 is a round island (Fig. 6B 2). On HaR-5652, only the metafossette is closed and it has a curving shape, pointing toward the anterior side. The hypoflexus is facing the paraflexus and the fold anterior to the hypoflexus is not as wide as the posterior fold. The mesoflexus is curving posteriorly, reaching the labial wall. There is no cement in the fossettes of all the specimens. On HaR-5646, two roots are preserved. An anterior one, wide, and a small, postero-lingual one (Fig. 6A 1). On HaR-5647, only one root is preserved, the postero-lingual one is broken off. On HaR-5652, no roots are formed but the base of the crown is visible on the anterior side. The roots of the M 2 on HaR-5643 are more exposed than for the M 1 and a postero-labial small root seem to have been broken off. M 3 – HaR-5644, HaR-5648 and HaR-5651 (Fig. 6 D-F) The shape of the specimens is elongated and triangular. The anterior side is rounded, and the posterior side is narrower than the anterior. HaR-5644 (Fig. 6D) and 5648 (Fig. 6E) are heavily worn with only the hypoflexus not closed. In these two teeth, the height of the hypostria, which is the only stria remaining, indicates that it is closing. HaR-5651 (Fig. 6F) is slightly to medium worn. Its parastria and mesostria are visible, although quite short. The metastria is worn off. The hypostria does not span the whole height of the tooth but is clearly visible and about twice the length of the parastria. The parafossette and metafossette of HaR-5644 and 5648 are rather small and about the same size. There is an additional posterior fossette of approximately the same size (Fig. 6D 1, E 1). The metafossette and the additional posterior fossette are oriented towards the postero-lingual side. On HaR- 5644, the hypoflexus is oriented towards the anterior side. On HaR-5648, the hypofossette meets the anterior side of the parafossette. The occlusal surface of HaR- 5651 is different from the other two teeth due to a difference in wear. On this tooth, the paraflexus is facing the hypoflexus and the fold anterior to the hypoflexus is not as wide as the posterior fold. The mesoflexus is open on the whole width of the tooth and forms a small indentation on the labial side. The metaflexus is closed but the metafossette is slightly open on the labial side indicating that the metaflexus was probably spanning the whole width of the occlusal surface. There is a small hole posteriorly, potentially indicating the presence of a posterior fossette. On HaR-5644, three roots are preserved. The anterior-most one is the widest and is curving like the anterior wall of the tooth. The antero-lingual one is small, erupting from the wider, most anterior root. The third one is located posteriorly. On HaR-5648, two roots are present. The anterior one is wide and following the anterior curve of the tooth. The posterior one is oval. On HaR-5651, no roots are preserved but the base of the crown is visible on the anterior side. REMARKS The right maxillary fragment HaR-5643 and the potentially corresponding M 3, HaR-5644, have been matched based on size, position, and degree of wear. The similarity in size and wear stages of the two upper tooth rows of Trogontherium (specimens HaR-5643 to HaR- 5648) indicate that they might have belonged to the same individual. The lack of longitudinal lines on the incisor of HaR-5642 is probably due to the fact that it is a juvenile specimen and therefore smaller and less developed (Hugueney et al. 1989). The attribution of our material to Trogontherium is based on several characteristics. These are the presence of elongated, cone shaped upper M 3s, P4 substantially bigger than the molars and a wrinkled enamel on the incisors (Mayhew 1978) as shown in Fig. 6G. The taxonomy of smaller species of Trogontherium is very debated but we can safely attribute our material to Trogontherium minus based on stratigraphic age and on size. A comparison with data from different species found in the literature confirms this (Fig. 7). The P 4 in our material are larger than most T. minus which could be a result of wear or of the tendency of the Trogontherium lineage to increase in size (Stefen 2011). We also notice that while the length of our specimens matches the range for T. minus, they are wider and reach the lower width range of Trogontherium cuvieri that is visible in the figure 3 of Fostowicz-Frelik 2008. This is coherent with the age and the assumption that T. minus and T. cuvieri are two representatives in the same evolutionary lineage proposed by Mayhew (1978) who also stated that only one species of Trogontherium was present at a time. However, Hugueney et al. (1989) have shown that T. cuvieri and T. minus coexisted during the Late Pliocene/Early Pleistocene. Some argue against the lineage hypothesis based on a too great size disparity (Fostowicz-Frelik 2008). However, our specimens show that the size disparity might not be as big as previously thought when compared to the data in the literature (Fostowicz-Frelik 2008, Heinrich 1998). This is mainly observed in the P4s as the width of the M 1/2 is closer to others found in the literature (Hugueney et al. 1989, Newton 1890). The measurements used for comparison are the maximum occlusal surface and can vary with wear, therefore one of our specimens is much less wide than the rest (Fig. 7). The shape and appearance of the incisor are comparable to that of T. cuvieri described by Newton (1902), although much smaller, further confirming the attribution to T. minus. This species is rare (Hugueney et al. 1989) and less well known than T. cuvieri (Stefen 2011), which makes it hard to compare our material. As stated by Mörs et al. (1998), there are only a few previously reported occurrences of Trogontherium in Germany from the Miocene and Pliocene. T. minus was previously found in deposits from Hambach of the same age (Mörs et al. 1998). It was also reported from the Slovakian MN 16a locality of Hajnačka I (Sabol et al. 2006) and from the MN 16 of Podpusk-Lebyazh’e (Western Siberia) where the most complete material was found (Vislobokova 1996). Trogontherium aff. minus was reported by Pascari (2021) from the Pliocene of Musaitu in the Taraclia district (Moldova), but the published measurements are inconsistent and were therefore not used here for comparison. Apoltsev & Rekovets (2015) place T. minus in the sub-genus Euroxenomys. However, we follow Hugueney & Duranthon (2012) and Mörs & Tomida (2018) who only place the Miocene Euroxenomys minutus and Euroxenomys nanus in the genus Euroxenomys. Trogontherium is an extinct genus of beavers, found from the Late Miocene (Mayhew 1978) to the Late Pleistocene (Yang et al. 2021). T. minus seems to have been restricted to Europe (Yang et al. 2021). Unlike Castor, Trogontherium is subhypsodont (Hugueney 1999; Stefen 2011), and seems to have a more terrestrial lifestyle (Fostowicz-Frelik 2008). The lower jaw HaR-5642 belongs to a juvenile individual, according to its erupting P4 and the early wear stage of the two preserved molars. Tentative age determination was done based on the timing of eruption of the p4. Different possible ages have been found in the literature based on studies of recent Castor. According to Mayhew (1978) the premolars erupt between six to ten months after birth and according (Heinrich & Maul (2020) p4s come into wear around the end of the first year. Hugueney & Escuillié (1996) consider individuals of Steneofiber with erupting p4s to be yearlings which correspond to individuals one year old or in their second year. According to these authors, it seems that our individual was around one year old, although probably a little less. However, these estimates are to be taken with caution as we do not know the lifespan nor the postnatal development of fossil species (Stefen & Rummel 2003)., Published as part of Laere, Gaëlle Van & Mörs, Thomas, 2023, Beavers and flying squirrels (Rodentia: Castoridae, Pteromyini) from the Late Pliocene of Hambach 11 C, Germany, pp. 223-241 in Geodiversitas 45 (7) on pages 228-233, DOI: 10.5252/geodiversitas2023v45a7, http://zenodo.org/record/7867111, {"references":["NEWTON E. 1890. - On some new mammals from the Red and Norwich Crags. Quarterly Journal of the Geological Society 46 (1 - 4): 444 - 453. https: // doi. org / 10.1144 / GSL. JGS. 1890.046.01 - 04.29","HUGUENEY M., GUERIN C. & POIDEVIN J. - L. 1989. - Decouverte de Trogontherium minus Newton 1890 (Rodentia: Castoridae) dans le Villafranchien inferieur de Perrier-Etouaires (Puy-de- Dome, France): implications phylogenetiques. Comptes rendus de l'Academie des Sciences. Serie 2, Mecanique, Physique, Chimie, Sciences de l'univers, Sciences de la Terre 309 (7): 763 - 768. https: // gallica. bnf. fr / ark: / 12148 / bpt 6 k 56640789 / f 769. item","MAYHEW D. F. 1978. - Reinterpretation of the extinct beaver Trogontherium (Mammalia, Rodentia). Philosophical Transactions of the Royal Society of London. B, Biological Sciences 281 (983): 407 - 438. https: // doi. org / 10.1098 / rstb. 1978.0004","STEFEN C. 2011. - A brief overview of the evolution of European tertiary beavers. Baltic Forestry 17 (1): 148 - 153.","FOSTOWICZ-FRELIK L. 2008. - First record of Trogontherium cuvieri (Mammalia, Rodentia) from the middle Pleistocene of Poland and review of the species. Geodiversitas 30 (4): 765 - 778.","HEINRICH W. - D. 1998. - Evolutionary trends in Trogontherium cuvieri (Mammalia, Rodentia, Castoridae) and their implications, in VAN KOLFSCHOTEN T. & GIBBARD P. L. (eds), The Dawn of the Quaternary. Mededelingen Nederlands Instituut voor Toegepaste Geowetenschappen TNO 60: 573 - 578.","NEWTON E. T. 1902. - Trogontherium from a Pleistocene Deposit in the Thames Valley. Geological Magazine 9 (9): 385 - 388. https: // doi. org / 10.1017 / S 0016756800181324","MORS T., VON KOENIGSWALD W. VON & VON DER HOCHT F. 1998. - Rodents (Mammalia) from the late Pliocene Reuver Clay of Hambach (Lower Rhine Embayment, Germany). Mededelingen Nederlands Instituut voor Toegepaste Geowetenschappen TNO 60: 135 - 160.","SABOL M., KONECNY V., VASS D., KOVACOVA M., DURIsOVA A. & TUNYI I. 2006. - Early Late Pliocene site of Hajnacka I (Southern Slovakia) - geology, palaeovolcanic evolution, fossil assemblages and palaeoenvironment. Courier Forschungsinstitut Senckenberg 256: 261 - 274.","VISLOBOKOVA I. 1996. - The Pliocene Podpusk-Lebyazh'e mammalian faunas and assemblage, western Siberia. Palaeontographia Italica 83: 1 - 23.","PASCARI V. 2021. - The evolution of Castorids (Mammalia, Rodentia) in the Republic of Moldova, in UNGUREANU L., TODERAs I., ZUBCOV E., DERJANSCHI V., ERHAN D. & NISTREANU V. (eds), Sustainable use and protection of animal world in the context of climate change, Moldova. Xth international conference of zoologists, Chisinau, 2020, abstracts: 357 - 361. https: // doi. org / 10.53937 / icz 10.2021.58","APOLTSEV D. A. & REKOVETS L. I. 2015. - Beavers of the Genus Trogontherium (Castoridae, Rodentia) From the Late Miocene of Ukraine. Vestnik Zoologii 49 (6): 519 - 528. https: // doi. org / 10.1515 / vzoo- 2015 - 0062","HUGUENEY M. & DURANTHON F. 2012. - Les Castoridae (Rodentia) de Sansan, in PEIGNE S. & SEN S. (eds), Mammiferes de Sansan. Museum national d'Histoire naturelle, Paris: 95 - 118 (Memoires du Museum national d'Histoire naturelle; 203).","MORS T. & TOMIDA Y. 2018. - Euroxenomys nanus sp. nov., a minute beaver (Rodentia, Castoridae) from the Early Miocene of Japan. Paleontological Research 22 (2): 145 - 149. https: // doi. org / 10.2517 / 2017 PR 013","YANG Y., LI Q., NI X., CHENG X., ZHANG J., LI H. & JIN C. 2021. - Tooth micro-wear analysis reveals that persistence of beaver Trogontherium cuvieri (Rodentia, Mammalia) in Northeast China relied on its plastic ecological niche in Pleistocene. Quaternary International 591: 70 - 79. https: // doi. org / 10.1016 / j. quaint. 2021.01.004","HUGUENEY M. 1999. - Family castoridae, in ROSSNER G. E. & HEISSIG K. (eds), The Miocene Land Mammals of Europe. Verlag Dr. Friedrich Pfeil, Munich: 281 - 300.","CZERNIELEWSKI M. 2022. - Castoridae (Rodentia) from the Villafranchian site of Weze 2 in southern Po land. Geological Quarterly 66: 18. https: // doi. org / 10.7306 / gq. 1650","LANGEVELD B. 2013. - Trogontherium cuvieri Fischer (Castoridae) van het strand van Hoek van Holland en de Zandmotor (Zuid-Holland). Cranium 30 (1): 8 - 12. https: // natuurtijdschriften. nl / pub / 713239","STEFEN C. & RUMMEL M. 2003. - Trogontherium (Euroxenomys) minutum (Castoridae: Mammalia) from Petersbuch 50, Miocene, South Germany. Neues Jahrbuch fur Geologie und Palaontologie-Monatshefte 1: 11 - 34. https: // doi. org / 10.1127 / njgpm / 2003 / 2003 / 11","HEINRICH W. - D. & MAUL L. C. 2020. - Mortality profiles of Castor and Trogontherium (Mammalia; Rodentia, Castoridae), with notes on the site formation of the mid-Pleistocene Hominin locality Bilzingsleben II (Thunringa, Central Germany). Fossil Imprint 76 (1): 40 - 58. https: // doi. org / 10.37520 / fi. 2020.004","HUGUENEY M. & ESCUILLIE F. 1996. - Fossil evidence for the origin of behavioral strategies in early Miocene Castoridae, and their role in the evolution of the family. Paleobiology 22 (4): 507 - 513. https: // doi. org / 10.1017 / S 0094837300016493"]}

Castor fiber Linnaeus, 1758 (Fig. 3) MATERIAL EXAMINED. — Left m1/2 (IPB-HaR-5641), left P4 (IPB- HaR-5637 and IPB-HaR-5640), left M1/2 (IPB-HaR-5638 and IPB-HaR-5639), incisor fragment (IPB-HaR-5653). MEASUREMENTS. — See Table 1. DESCRIPTIONS I – HaR-5653 (Fig. 3A). A fragment of an incisor exhibits the smooth enamel and a rather flattened surface with both lateral edges curved. N m1/2 – HaR-5641 (Fig. 3B) Unworn tooth germ showing the original cusp configuration. Rectangular shape, the labial side is slightly shorter than the lingual side. There is a small cusplet on the labial side of the protoconid, below the occlusal surface (Fig. 3B 2). All the striids reach the base of the tooth. There is some cement in the striids. The metaconid is the highest cusp, followed by the paraconid. The hypoflexid and metaflexid are “face to face”. The hypoflexid is oriented posteriorly. The paraflexid and mesoflexid are oriented anteriorly. No roots are developed. P4 – HaR-5637 and HaR-5640 (Fig. 3C, D) HaR-5637 (Fig. 3C) is slightly worn and preserved in a maxillary fragment with no other tooth in situ whereas HaR-5640 (Fig. 3D) has an occlusal surface too damaged to determine a wear stage. There is clearly cement in the striae. On HaR- 5637, they all seem to run through the entire height of the tooth. This is not the case on HaR-5640 where the end of the parastria is visible and the mesostria seems to be closing. The anterior and posterior sides are slightly rounded. The lingual side is shorter than the labial. Although on HaR-5640, the outer wall is damaged, it seems that its posterior side was flatter than that of HaR-5637. The hypoflexus and the paraflexus are “face to face”. On HaR-5637, the hypoflexus is curving anteriorly. The mesoflexus and paraflexus are curving anteriorly, then posteriorly and are parallel to each other. The mesoflexus and metaflexus almost reach the posterior wall. On HaR-5640, the mesoflexus is broken but seems to be curving posteriorly and the metaflexus is not preserved. HaR-5637 does not have formed roots, the base is still open. On HaR-5640, this part is not preserved. M 1/2 – HaR-5638 and HaR-5639 (Fig. 3E, F) Both teeth are slightly worn. The shape is square with the anterior side slightly rounded and the lingual side slightly smaller than the labial side. Both characteristics are less marked than on the P4. The hypostria runs through the entire height of the tooth. On the labial side, the parastria is the shortest on HaR-5638 and the mesostria the longest almost reaching the end of the tooth crown. On HaR-5639 the metastria is the shortest and the parastria and mesostria are about the same length. There is clearly cement in the striae. The paraflexus and hypoflexus are “face to face”. On HaR-5638, they are both oriented towards the anterior side and on HaR-5639, the hypoflexus is going anteriorly and the paraflexus is rather straight and horizontal. The mesoflexus changes orientation mid-way to go toward the posterior side and almost reaches the posterior wall, the angle of the curve is close to 90° on HaR-5639. On this tooth, the metaflexus is dipping anteriorly at its mid-point whereas on HaR-5638, the metaflexus is going slightly posteriorly but is relatively straight and reaches the end of the mesoflexus. The enamel of the hypoflexus is thickened on its anterior side and so is the enamel of the mesoflexus. Both do not have roots. REMARKS The attribution to Castor fiber was made based on the observation of several characters. Firstly, the smooth enamel of the incisor and its almost flat face (Newton 1902; Fostowicz-Frelik 2008; Cuenca-Bescós et al. 2015) but also the presence of cement (Mayhew 1978) and the lack of roots (Rekovets et al. 2009) as well as the fact that the hypostria runs down the entire height of the tooth, unlike in Trogontherium (Fostowicz-Frelik 2008). Moreover, the size and morphology of the specimens are coherent with other finds, for example from Early Pleistocene sites in Romania and Spain (Olteţ River Valley, Gran Dolina and Sima del Elefante) and from the Middle Pleistocene of Portugal (Gruta da Aroeira) (Cuenca-Bescós et al. 2015; 2021; Terhune et al. 2020) and with recent specimens (personal observations in the collections of the NRM). Castor fiber has previously been reported from the Late Pliocene of Hambach 11 (MN 16a) by Mörs et al. (1998). It was also found in the Late Pliocene (MN 16a) Slovakian locality of Hajnačka I (Sabol et al. 2006). Castor fiber is one of two species of Castor still present today (Stefen 2011). The genus Castor appears in the European fossil record during the Late Miocene (Hugueney 1999), and is already present in Germany at this time (Cuenca-Bescós et al. 2015). The species Castor fiber appears in the middle Villafranchian (Barisone et al. 2006). The quasi absence of wear on HaR-5641 indicates that it belonged to a really young individual, less than five months old according to the tooth pattern (Stefen 2009)., Published as part of Laere, Gaëlle Van & Mörs, Thomas, 2023, Beavers and flying squirrels (Rodentia: Castoridae, Pteromyini) from the Late Pliocene of Hambach 11 C, Germany, pp. 223-241 in Geodiversitas 45 (7) on page 226, DOI: 10.5252/geodiversitas2023v45a7, http://zenodo.org/record/7867111, {"references":["NEWTON E. T. 1902. - Trogontherium from a Pleistocene Deposit in the Thames Valley. Geological Magazine 9 (9): 385 - 388. https: // doi. org / 10.1017 / S 0016756800181324","FOSTOWICZ-FRELIK L. 2008. - First record of Trogontherium cuvieri (Mammalia, Rodentia) from the middle Pleistocene of Poland and review of the species. Geodiversitas 30 (4): 765 - 778.","CUENCA-BESCOS G., ROSELL ARDEVOL J., MORCILLO-AMO A., GALINDO-PELLICENA M. A., SANTOS E. & COSTA R. M. 2015. - Beavers (Castoridae, Rodentia, Mammalia) from the Quaternary sites of the Sierra de Atapuerca, in Burgos, Spain. Quaternary International 433: 263 - 277. https: // doi. org / 10.1016 / j. quaint. 2015.10.072","MAYHEW D. F. 1978. - Reinterpretation of the extinct beaver Trogontherium (Mammalia, Rodentia). Philosophical Transactions of the Royal Society of London. B, Biological Sciences 281 (983): 407 - 438. https: // doi. org / 10.1098 / rstb. 1978.0004","REKOVETS L., KOPIJ G. & NOWAKOWSKI D. 2009. - Taxonomic diversity and spatio-temporal distribution of late Cenozoic beavers (Castoridae, Rodentia) of Ukraine. Acta Zoologica Cracoviensia - Series A: Vertebrata 52 (1): 95 - 105. https: // doi. org / 10.3409 / azc. 52 a _ 1 - 2.95 - 105","CUENCA-BESCOS G., SANZ M., DAURA J. & ZILHAO J. 2021. - The fossils of Castor fiber from the middle Pleistocene site of Gruta da Aroeira (Portugal) and human-beaver interaction. Quaternaire 32: 1 - 10. https: // doi. org / 10.4000 / quaternaire. 14975","TERHUNE C. E., CURRAN S., CROITOR R., DRsGUsIN V., GAUDIN T., PETCULESCU A., ROBINSON C., ROBU M. & WERDELIN L. 2020. - Early Pleistocene fauna of the Oltet River Valley of Romania: Biochronological and biogeographic implications. Quaternary International 553: 14 - 33. https: // doi. org / 10.1016 / j. quaint. 2020.06.020","MORS T., VON KOENIGSWALD W. VON & VON DER HOCHT F. 1998. - Rodents (Mammalia) from the late Pliocene Reuver Clay of Hambach (Lower Rhine Embayment, Germany). Mededelingen Nederlands Instituut voor Toegepaste Geowetenschappen TNO 60: 135 - 160.","SABOL M., KONECNY V., VASS D., KOVACOVA M., DURIsOVA A. & TUNYI I. 2006. - Early Late Pliocene site of Hajnacka I (Southern Slovakia) - geology, palaeovolcanic evolution, fossil assemblages and palaeoenvironment. Courier Forschungsinstitut Senckenberg 256: 261 - 274.","STEFEN C. 2011. - A brief overview of the evolution of European tertiary beavers. Baltic Forestry 17 (1): 148 - 153.","HUGUENEY M. 1999. - Family castoridae, in ROSSNER G. E. & HEISSIG K. (eds), The Miocene Land Mammals of Europe. Verlag Dr. Friedrich Pfeil, Munich: 281 - 300.","BARISONE G., ARGENTI P. & KOTSAKIS T. 2006. - Plio-Pleistocene evolution of the genus Castor (Rodentia, Mammalia) in Europe: C. fiber plicidens of Pietrafitta (Perugia, Central Italy). Geobios 39 (6): 757 - 770. https: // doi. org / 10.1016 / j. geobios. 2005.10.004","STEFEN C. 2009. - Intraspecific variability of beaver teeth (Castoridae: Rodentia). Zoological Journal of the Linnean Society 155 (4): 926 - 936. https: // doi. org / 10.1111 / j. 1096 - 3642.2008.00467. x"]}

Laere, Gaëlle Van, Mörs, Thomas (2023): Beavers and flying squirrels (Rodentia: Castoridae, Pteromyini) from the Late Pliocene of Hambach 11C, Germany. Geodiversitas 45 (7): 223-241, DOI: 10.5252/geodiversitas2023v45a7

A list of 40 species is presented of the rodents and insectivores collected during a 15-year period from the Republic of Mordovia. The dataset contains more than 24,000 records of rodent and insectivore species from 23 districts, including Saransk. A major part of the data set was obtained during expedition research and at the biological station. The work is based on the materials of our surveys of rodents and insectivorous mammals conducted in Mordovia using both trap lines and pitfall arrays using traditional methods.

Modern beavers (Castor) are prolific ecosystem engineers and dramatically alter the landscape through tree harvesting and dam building. Little is known, however, about the evolutionary drivers of their woodcutting behaviour. Here we investigate if early woodcutting behaviour in Castoridae was driven by nutritional needs. We measured stable carbon and nitrogen isotopes (δ13C and δ15N) of coeval subfossil plants and beaver collagen (Dipoides sp.) from the Early Pliocene, High Arctic Beaver Pond fossil locality (Ellesmere Island), in order to reconstruct Dipoides sp. diet. Isotopic evidence indicates a diet of woody plants and freshwater macrophytes, supporting the hypothesis that this extinct semiaquatic beaver engaged in woodcutting behaviour for feeding purposes. In a phylogenetic context, the isotopic evidence implies that woodcutting and consumption of woody plants can be traced back to a small-bodied, semiaquatic Miocene castorid, suggesting that beavers have been consuming woody plants for over 20 million years. We propose that the behavioural complex (swimming, woodcutting, and consuming woody plants) preceded and facilitated the evolution of dam building. Dam building and food caching behaviours appear to be specializations for cold winter survival and may have evolved in response to late Neogene northern cooling.

Five castorid teeth from the (early) middle Miocene locality Gracanica in Bosnia-Herzegovina, probably originating from lower lacustrine lignite-rich deposits, were available for study. These teeth from the upper jaw are similar in preservation, wear stage, and size and may represent only one single individual. Due to their size and morphology (mainly state of hypsodonty and closing hypostria in P4), they are referred to Stenefiber depereti. Since a semiaquatic lifestyle is assumed for Steneofiber, it may be assumed that the teeth are of autochthonous origin.

The work presents the first results of annual monitoring of a beaver population on the territory of Ostrovtsovskaya Lesostep' (State Nature Reserve Privolzhskaya Lesostep', Penza region). In 2014–2017 all water-courses and water-bodies, including the River Khoper, River Selimutka, River Yuzhnaya and several oxbows of the Khoper were investigated twice a year for assessing the beaver abundance using the method of settlements capacity. The mean density of dams was 7.7 dams/km of watercourse, the maximum was on the River Yuzhnaya – 10.8 dams/km, and the minimum was on the River Selimutka – 5.5 dams/km. During the study period 10 to 13 beaver settlements were observed, the total abundance of beavers tends to decrease (from 42 to 30 animals). The present density of beavers and a lack of food resources limit a further increase of the species abundance.

The article presents research on the population density of the Eurasian beaver in the large, medium and small rivers of the Republic of Mordovia. The population density of the beaver in the large rivers of the region varies from 0.45 to 0.62 colonies per km (average 0.52). The population density in medium rivers ranges from 0.36 to 0.48 colonies per km (average 0.4). In small rivers, population density ranges from 0.2 to 0.94 colonies per km (average 0.46). The total number of beavers in the region is about 17,000 individuals as at 2016.

The Eurasian beaver, Castor fiber is known from the Pleistocene in Europe, although there are references to the presence of the genus Castor since the Miocene, ca. 10 Ma. Beavers are present in the Iberian Peninsula since the Pliocene, though the first appearance of Castor fiber took place in the Early Pleistocene levels of the localities of the Sierra de Atapuerca, where the fossil beaver remains are found in the lower levels of Sima del Elefante and Gran Dolina (Early Pleistocene), Galeria de las Estatuas (Late Pleistocene) and Portalon (Holocene). The presence of fossil beavers suggests humid and mild climatic conditions in the Early Pleistocene levels of Gran Dolina and Sima del Elefante. During the Middle Pleistocene, although conditions for beavers seemed favourable, they disappeared from Atapuerca, appearing again during the Late Pleistocene and the Holocene.

The present paper contains information on a new beaver colony discovered in the Chornyi mochar tract, which is located in the lowland part of Transcarpathia (= Zakarpattia Region). This rodent species disappeared from the territory of Transcarpathia most likely in the 18th century. Its first reappearance was recorded in 2003. Since, the Eurasian beaver has demonstrated a rapid expansion, primarily along the main rivers. The discovered by us colony allows to suggest that the beaver is continuing its dispersal, entering far into the main river’s tributaries and other shallower water bodies. Consequently, we are witnessing not only the expansion of the species’ geographical range, but also the enlargement of the number of habitat types occupied by the animal. The possibilities and supposed consequences of the species’ further expansion within the tract are shown as well.

The large Miocene beavers (Castoridae) Anchitheriomys Roger, 1898, and Amblycastor Matthew, 1918, have been often considered as synonyms (Flynn and Jacobs 2008). Most recently, they have been distinguished as separate genera based on the morphology of the dentary: Amblycastor restricted to North America and Anchitheriormys limited to Eurasia (Mors and Hulbert 2010). However, the dentary that was cited as evidence for the separation lacks cheek teeth and its specific identification cannot be verified. In addition, a previously undescribed specimen from the type area of “Amblycastor” fluminis Matthew, 1918, demonstrates that the morphologies used to separate these genera are not consistent with the North American specimens; thus, the two genera are synonymous and the North American species should be referred to Anchitheriomys.

Beavers are well-known for their ability to fell large trees through gnawing. Yet, despite this impressive behavior, little information exists on their masticatory musculature or the biomechanics of their jaw movements. It was hypothesized that beavers would have a highly efficient arrangement of the masticatory apparatus, and that gnawing efficiency would be maintained at large gape. The head of an American beaver, Castor canadensis, was dissected to reveal the masticatory musculature. Muscle origins and insertions were noted, the muscles were weighed and fiber lengths measured. Physiological cross-sectional areas were determined, and along with the muscle vectors, were used to calculate the length of the muscle moment arms, the maximum incisor bite force, and the proportion of the bite force projected along the long axis of the lower incisor, at occlusion and 30° gape. Compared to other sciuromorph rodents, the American beaver was found to have large superficial masseter and temporalis muscles, but a relatively smaller anterior deep masseter. The incisor bite force calculated for the beaver (550–740 N) was much higher than would be predicted from body mass or incisor dimensions. This is not a result of the mechanical advantage of the muscles, which is lower than most other sciuromorphs, but is likely related to the very high percentage (>96 %) of bite force directed along the lower incisor long axis. The morphology of the skull, mandible and jaw-closing muscles enable the beaver to produce a very effective and efficient bite, which has permitted beavers to become highly successful ecosystem engineers.

Tesakov, Alexey S., Titov, Vadim V., Simakova, Alexandra N., Frolov, Pavel D., Syromyatnikova, Elena V., Kurshakov, Sergey V., Volkova, Natalia V., Trikhunkov, Yaroslav I., Sotnikova, Marina V., Kruskop, Sergey V., Zelenkov, Nikita V., Tesakova, Ekaterina M., Palatov, Dmitry M. (2017): Late Miocene (Early Turolian) Vertebrate Faunas And Associated Biotic Record Of The Northern Caucasus: Geology, Taxonomy, Palaeoenvironment, Biochronology. Fossil Imprint 73 (3-4): 383-444, DOI: 10.2478/if-2017-0021, URL: http://dx.doi.org/10.2478/if-2017-0021

This is the first study to describe the results of measurement of three information parameters of morphological diversity (entropy, the measure of organization, and the Kullback-Leibler divergence) in the course of postnatal development of the skull in the populations of two rodent species (greater mole rat (Spalax microphthalmus Guld.) and Eurasian beaver (Castor fiber (L.)). The terms “morphosystem” and “morphological space” and its structure are introduced. Within the framework of the developed approach, “morphological diversity” is considered as a variable associated with the morphological space structure. Testing the hypothesis of the dominance of self-organization processes and an increase in the organization of the morphological diversity of the skull in the course of ontogeny showed its inconsistency. The morphosystem of the skull of the studied species undergoes transitions between more organized and less organized states, periodically approaching and departing from the “steady state.” Such dynamics characterizes the morphosystem of the skull as a dynamic and nonlinear system.

A large sample of microvertebrates from the Sarmatian s. str. of Gratkorn (Austria, Styria) has recently been recovered. The recovered rodent fauna is diverse and includes a few castorid remains that are described here. Such remains comprise isolated teeth, a palate and a fragmentary skull that are ascribed to the small-sized beaver Euroxenomys minutus minutus (Von Meyer, 1838). These finds are discussed with regard to the Austrian Miocene castorid record.

Palaeocastorine beavers were diverse members of the burrowing fauna of the Oligocene of North America best known from the Great Plains and the Great Basin. Palaeocastorines are also found in the northern Rocky Mountains. Several specimens of Capacikala, Euhapsis, and Palaeocastor have been reported from Montana within the Cabbage Patch beds fauna. New occurrences of palaeocastorine beavers from the Fort Logan Formation of central Montana show that the fauna there included Palaeocastor fossor, Capacikala sp., Palaeocastor sp., and three specimens of a species previously known only from the John Day Formation of Oregon: Palaeocastor peninsulatus. The three specimens include crania and associated postcrania forming an ontogenetic series from a juvenile to a mature adult. Careful examination of these specimens shows that morphological changes throughout ontogeny are associated with increased burrowing ability in adults. Palaeocastor peninsulatus is a scratch-digger with few cranial adaptations to burrowing susceptible to change with maturity. Dental characters, however, are modified with wear and vary greatly across individuals of similar wear stage. Cranial morphology thus appears to be a reliable source of taxonomic information in palaeocastorines unlike dental material. These new specimens provide evidence for increased chisel-tooth digging in adults compared to juveniles as is observed throughout the evolution of palaeocastorines. This study demonstrates the need for future work focusing on intraspecific variation to help better define species boundaries among palaeocastorines and improve phylogenetic analyses.

The pattern of morphological variability in translocated groups of mammals has been studied based on the example of two beaver subspecies (Castor fiber orientoeuropaeus and Castor fiber belorussicus) with the documented history of population formation. The variability in the quantitative and quantitative traits in the formed populations is not characterized by a single direction. The main trend is an increase in the diversity of adaptive norms in relation to body sizes. A slightly marked increase is observed in the level of fluctuating asymmetry, a reduction in polymorphisms in nonmetric traits, and an increase in the percentage of rare aberrations that may be associated with inbreeding taking place during the formation of prapopulations. The results of this study allow this intraspecific differentiation to be considered an effect of adaptive variability (adaptatiogenesis) or subspecies hybridization. As for stochastic processes (gene drift and founder effect), they seem to have no significant effect on the morphological variability. The differences between non-metric and metric traits indicate the peculiarity of population groups.

Don E. Wilson, Thomas E. Lacher, Jr, Russell A. Mittermeier (2016): Castoridae. In: Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I. Barcelona: Lynx Edicions: 150-168, ISBN: 978-84-941892-3-4, DOI: http://doi.org/10.5281/zenodo.6584880

Don E. Wilson, Thomas E. Lacher, Jr, Russell A. Mittermeier (2016): Castoridae. In: Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I. Barcelona: Lynx Edicions: 150-168, ISBN: 978-84-941892-3-4, DOI: http://doi.org/10.5281/zenodo.6584880

1. Eurasian Beaver Castor fiber French: Castor d'Europe / German: Eurasischer Biber / Spanish: Castor euroasiatico Other common names: European Beaver Taxonomy. Castor fiber Linnaeus, 1758, “Habitat in Europa, Afiee, Americ.” Eight subspecies have been recognized based on geography and morphological differences. However, recent analysis of both mtDNA and nDNA suggests that there are only two phlyogroups, a western and an eastern group, and neither can be considered a separate subspecies. Monotypic. Distribution. N, C & E Europe, from Scandinavia and Russia to S France (Rhone Delta), extensive and small isolated populations in W & C Siberia, and in the Amur Basin, Russian Far East, and small relic populations in the Altai region of SW Mongolia and NWChina. Descriptive notes. Head—body 800-900 mm, tail 200-300 mm; weight 15-20 kg (rarely, 30-40 kg). Eurasian Beavers are the second largest rodent species (tied with the North American Beaver, C. canadensis) and the largest European rodent. There is no physical sexual dimorphism. Eurasian Beavers are stocky, robust rodents with relatively massive skeletons. Fronts of incisors are reddish-orange, caused byiron concentration for strength. Coat color ranges from light brown to darker reddish-brown to almost black; brownish color is most common. Eurasian Beavers have long guard hairs and dense underfur. Many other physical adaptations are associated with their aquatic habits. Eurasian Beavers have small forelimbs and hands, with powerful digging claws, and webbed hindfeet. Ears and nose can close; eyes have a membrane that covers them when diving. Tail is prominent and dorsal-ventrally flattened, and it can be more or less oval-shaped depending on geographical location. Habitat. Associated with all types of freshwater wetlands, from large rivers to small streams, lakes, and ponds, and also along wetland systems associated with agricultural land such as irrigation canals and fishponds. Eurasian Beavers are most closely associated with wetlands that contain species in the family Salicaceae (e.g. willows, Salix spp., and aspens and poplars, both Populus spp.), but theyare also found in areas that lack these species. They also use ponds and lakes that contain water lilies (Nuphar spp. and Nymphaea spp., Nymphaeaceae), which might be related to sodium availability. Eurasian Beavers are found from lowland areas to mountainous regions; in mountain areas, stream gradient limits colonization. They can tolerate human activity and are found living in large rivers in cities (e.g. Vienna) and on rivers with industrial sites (e.g. Switzerland). Widths of riparian borders along streams and rivers are probably associated with habitat use. Food and Feeding. Eurasian Beavers eat a variety ofriparian woody and herbaceous plants. They are generalist herbivores but can be highly specialization in their food selection. They prefer willows and aspens but also eat other deciduous species including maples (Acer spp., Aceraceae); alders (Alnus spp.) and birches (Betula spp., both Betulaceae); and oaks (Quercus spp., Fagaceae). They might seasonally eat evergreens such as pines (Pinus spp.), firs (Abies spp.), and hemlocks (7suga spp., all Pinaceae). They also seasonally eat many species of herbaceous plants. Eurasian Beavers take trees that are much larger than theyare as food items, but they primarily eat branches, bark with associated cambium layer, and leaves. They have associated gut micro-biota that helps with some cellulose digestion. Cutting of trees and woody vegetation is most pronounced in autumn but can occur in all seasons. Across their distribution, Eurasian Beavers build food caches of branches in autumn that they eat during winter—variable depending on geographical location. Although they use most riparian species, woody and herbaceous, they concentrate on a few species, to some degree, for the majority oftheir diet. Breeding. Eurasian Beavers breed once a year, and females come into estrus in December-May, with a peak in January-February. Estrus lasts 12-24 hours, and iffertilization does not occur, females come into estrus again. Gestation is 100-110 days, and young are born in spring or early summer. Litter size is 1-6 young but averages 2. Males and females become reproductively active at 2-3 years of age. Eurasian Beavers are socially monogamous if not genetically monogamous, and form pair bonds thatlast for years. Rarely, multiple pregnant females have been reported in one family group. Copulation might occur in the water or in the lodge or burrow. Eurasian Beavers live 8-15 years in the wild—relatively long for a rodent. Activity patterns. Eurasian Beavers are nocturnal, becoming active in the evening (17:00-19:00 h) and remaining active until morning (06:00-08:00 h). They might return to their daytime rest site (lodge or burrow) many times during an activity period. When active, theypatrol their territory, swim, feed, and groom. Interactions with other family members do occur, most often among adults and young. In autumn, they are active cutting woody vegetation, building a food cache, and putting mud and branches on their lodges. Movements, Home range and Social organization. Eurasian Beavers live in family groups (a mated pair of adults, young-of-the-year, and yearlings). They are territorial and mark territorial boundaries with scent mounds. They move within their territories and might even move between territories in spring and summer. Movements tend to be only a few hundred meters. Two-year-old Eurasian Beavers generally disperse from their natal areas in spring, summer, or autumn. These movements average 5-10 km but might be longer depending on quality ofavailable habitat and density of the population. There is some indication that females disperse farther than males, but this might not be consistent. Home ranges are usually represented as linear lengths of shoreline occupied and are 0-5-1-5 km. Eurasian Beavers tend to forage within 30 m of the shoreline, although forays of 100 m or more are observed. Movements within a territory are dependent of habitat quality. Adults are dominant to young individuals within a family, and no consistent dominance of one sex over the other has been documented. There is evidence that Eurasian Beavers recognize anal gland secretions or castoreum scents oftheir family members and nearest neighbors more than less familiar individuals and react more strongly to unfamiliar scent. Status and Conservation. Classified as Least Concern on The IUCN Red List. The Eurasian Beaver has come back from near extinction across its distribution due to conservation efforts, hunting bans, and active reintroduction programs. It was regionally extinct by the end of the 19" century and existed in small populations in isolated refugia in Central Europe, Norway, and Russia. From an estimated 1200 individuals in the early 1900s, the Eurasian Beaver has increased to a conservative estimate of 700,000 individuals, and mostlikely, the overall population has more than one million individuals due to these efforts. Eurasian Beavers were valued for their fur, meat, and castoreum (exudates from castor sacs) for medicinal purposes. Composition of castoreum is influenced by diet and reportedly contains a large amount of salicylic acid, an active ingredient in aspirin. Castoreum has been used to treat headaches, pains, and digestive disorders. Numerous place names that refer to beavers across Europe attest to their long association with humans. Viable populations now exist throughout western and central Europe, and hunting seasons are allowed in many countries. Introduction efforts have brought the Eurasian Beaver back from the brink of extinction, and recent reintroduction efforts are underway in new areas such as Spain and the UK. Historical distributions include Portugal, Italy, and the South Balkan region including Turkey, but no populations currently exist there. A measure of the return of the Eurasian Beaver is the number of complaints of damage due to flooding caused by beaver dams that impound water and raise the water table. Loss of timber and flooding of agricultural land are occurring in areas where Eurasian Beavers had been absent from the landscape for hundreds of years. Impacts of increasing and spreading beaver populations on agriculture, other land uses, human structures, managed forests, roadways, road culverts, and railway beds, and how humans will learn to live with these impacts, are continuing concerns. Nevertheless, the successful return of the Eurasian Beaver andits ability to increase and enhance wetland function represent a conservation success story. Eight geographical subspecies of the Eurasian Beaver have been traditionally recognized based on geographic distribution and morphological differences. However, recent genetic analysis does not support subspecies status for any of the geographical groups in Eurasia. The Chinese/Mongolian form (historically considered the subspecies birulai) and the Tuva form (historically considered the subspecies tuvinicus) are the most vulnerable to local extinction given their small population sizes and distribution. There is still the possibility for human activity to negatively impact the Eurasian Beaver, especially because human use of water sources and wetlands might not be compatible with sustainable beaver populations. The issue of genetic purity of the Eurasian Beaver in various locations is also an ongoing conservation issue. Introduced populations of North American Beavers exist in Finland, Russian Karelia, Russian Far East (Kamchatka and Sakhalin Island). It is also possible that North American Beavers are present in Luxembourg, France, Germany, and Austria due to animals escaping from zoos or animal parks. A number of active projects are underway to use genetic methods to identify North American Beavers and remove them as competitors to the native Eurasian species. The similarity in form and behavior between the two beaver species creates concern that the invasive North American Beaver might be a competitor with the native Eurasian Beaver. Bibliography. Biedrzycka et al. (2014), Busher & Dzieciolowski (1999), Busher & Hartman (2009), Coles (2006), Danilov et al. (2011a, 2011b), Dewas et al. (2012), Doboszynska & Zurowski (1983), Durka et al. (2005), Frosch et al. (2014), Gabrys & Wazna (2003), Gard (1961), Halley & Rosell (2002), Hartman (1994, 1996), Horn, Durka et al. (2011), Horn, Prost et al. (2014), Jenkins & Busher (1979), Kuehn et al. (2000), Lahti & Helminen (1974), Lavrov & Orlov (1973), Mors & Stefen (2010), Nolet & Rosell (1998), Parker et al. (2012), Richard (1967, 1973, 1980, 1983), Rosell & Pedersen (1999), Rosell & Schulte (2004), Rosell & Sun Lixing (1999), Rosell et al. (2005), Sharpe & Rosell (2003), Sjoberg & Ball (2011), Troszynski (1975), Wilsson (1968, 1971)., Published as part of Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Castoridae, pp. 150-168 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions on pages 166-167, DOI: 10.5281/zenodo.6584880

2. North American Beaver Castor canadensis French: Castor du Canada / German: Kanadischer Biber / Spanish: Castor americano Other common names: American Beaver, Canadian Beaver Taxonomy. Castor canadensis Kuhl, 1820, “Ad fretum Hudsoni, [Hudson Strait or Bay],” Canada. Twenty-four subspecies have been described and used in the past, but extreme exploitation and mixing of populations during reintroductions seem to make these meaningless. More genetic analysis of both mtDNA and nDNA will require a reevaluation of the concept of geographic subspecies based on morphological differences. There is currently no genetic evidence to support subspecies in the North American species. Monotypic. Distribution. North America, from the Mackenzie River Delta, Northwest Territories, Canada, S throughout Canada and USA, excluding peninsular Florida and arid parts of the SW, to N Mexico (Baja California to Tamaulipas). North American Beavers have been introduced into Europe (Finland, Russia, Central Europe), Russian Far East (Kamchatka and Sakhalin Island), and Tierra del Fuego, Argentina. Descriptive notes. Head—body 800-900 mm, tail 200-300 mm; weight 15-20 kg (rarely, 30-40 kg). The North American Beavers is the second largest rodent species in the world (tied with the Eurasian Beaver, C. fiber) and the largest North American rodent. Sexes are externally similar, with no sexual dimorphism. North American Beavers are stocky, robust rodents with relatively massive skeletons. Fronts of incisors are reddishorange, caused by iron concentration for strength. Coat color ranges from light brown or blonde to darker reddish-brown to almost black. Reddish-brown color, called Algonquin, is most common; very dark to blackish fur is rare in natural populations. Fur consists of long, course guard hairs and soft, dense underfur. Underfur was processed into felt for the European hat industry that flourished from the late 16™ century to the mid-19" century. Other physical adaptations are associated with their aquatic habits. North American Beavers have small forelimbs and hands, with powerful digging claws, and completely webbed hindfeet. Ears and nose can close like valves; eyes have a membrane that covers them when diving. Tail is prominent and dorsal-ventrally flattened, oval-shaped, and brownish black in color. Tail is scaly in appearance, with sparse fine hairs; it is darker and hairs more prominent in young individuals. Habitat. Associated with all types of freshwater wetlands from large rivers to small streams, lakes, and ponds and along wetland systems associated with agricultural land such as irrigation canals. North American Beavers are most closely associated with wetlands that contain species in the family Salicaceae (e.g., willows, Salix spp., and aspens and poplars, both Populus spp.), but they are also found in areas that lack these species. They are found in ponds and lakes that contain waterlilies (Nuphar and Nymphaea, Nymphaeaceae), which might be related to sodium availability. North American Beavers occur from lowland areas to mountainous regions up to tree line (elevations of 2000-2500 m). In mountain areas, stream gradient limits colonization. They can tolerate human activity and are found living on ponds and large rivers in cities (e.g. Chicago and Washington D.C.) and on rivers in more historically industrial areas (e.g. Martinez, California). Food and Feeding. North American Beavers eat a variety of riparian woody and herbaceous plants. They are generalist herbivores but can be highly specialization in their food selection, usually relying on 2-5 species for the bulk of their diets regardless of plant diversity. They prefer willows and aspen but also eat many other deciduous species including maples (Acer spp., Aceraceae); alders (Alnus spp.) and birches (Betula spp., both Betulaceae); oaks (Quercus spp., Fagaceae); black walnut (Juglans nigra, Juglandaceae); and a variety of fruit bearing trees. They might seasonally eat evergreens such as pines (Pinus spp.), firs (Abies spp.), and hemlocks (75uga spp., all Pinaceae). They eat herbaceous plants seasonally, taking more in spring and summer than in other seasons. North American Beavers, like Eurasian Beavers, take trees that are much larger than they are as food items, but they primarily eat branches, bark with associated cambium layer, and leaves. They have associated gut micro-biota that helps in partial cellulose digestion. Cutting of tree and woody vegetation is most pronounced in autumn but can occur during all seasons. Across their distribution, North American Beavers build food caches of branches from woody species in autumn that they eat in winter when plant productivity is low and mobility is restricted by snow and ice. Breeding. North American Beavers breed once a year, and females come into estrus in December—May, with a peak in January-February. Estrusis 12-24 hours, and if fertilization does not occur, females might come into estrus again. Gestation is 100-110 days, and young are born in spring or early summer. Littersize is 1-6 young but averages 2—4. Males and females become reproductively active at 2-3 years of age. North American Beavers are socially monogamous, if not genetically monogamous, and form pair bonds that last for years. Rarely, multiple pregnant females have been reported in one family group, usually associated with high densities or populations under extreme exploitation. Copulation occurs in the water in a ventral-ventral position or in a lodge or burrow. North American Beavers live 8-15 years in the wild—relatively long for a rodent. Survival is slightly lower for young individuals but generally similar for all age classes. Activity patterns. North American Beavers are nocturnal, becoming active in the evening (17:00-19:00 h) and remaining active until morning (06:00-08:00 h). They might return to their daytime rest site (lodge or burrow) many times during an activity period. When active, they patrol their territory and dams, swim, feed, and groom. Interactions outside of the rest site with other family members are observed, although they are not common. Most often interactions are among adults and young individuals, especially young-of-the-year. North American Beavers are relatively inactive in winter, and in extreme northern parts of their distribution, they might exhibit a type of winter torpor with little or no movement, although thisis still highly speculative. Over much of their northerly distribution, mobility is restricted by snow and ice in winter. In autumn, they are active cutting woody vegetation, building a food cache, and putting mud and branches on their lodges for insulation and protection. Movements, Home range and Social organization. North American Beaverslive in family groups (a mated pair of adults, young-of-the-year, and yearlings from the previous year), often called a colony. They are territorial and mark territorial boundaries with scent mounds. They move throughouttheir territories and might even move between territories during spring and summer. Movements tend to be only a few hundred meters. Two-year-old beavers generally disperse from their natal areas in spring, summer, or autumn. Dispersal movements are 5-10 km, but they might be longer depending on availability of quality habitat and density of the population. There is some indication that females disperse farther than males, but this might not be consistent for all populations. Home ranges are usually represented as linear lengths of shoreline occupied and are 0-5-1-5 km. North American Beavers tend to forage within 30 m of the shoreline although longer forays of 100 m or more are observed, usually for preferred foods like aspen. Adults are dominant to young individuals within a family, and no consistent dominance of one sex over the other within an age group has been consistently documented. Young individuals most often initiate social interactions. There is evidence that beavers recognize anal gland secretions and castoreum scents of their family members and nearest neighbors more than less familiar individuals and react more strongly to unfamiliar scent. Evidence is clearer for this in the Eurasian Beaver, but given their morphological and behavioral similarities,it should also be true for the North American Beaver. Status and Conservation. Classified as Least Concern on The IUCN Red List. The North American Beaver currently has a stable population across its distribution. It was the target of the European fur trade from the late 16" century to the mid-19" century. In many areas of the USA, populations were extirpated and regionally extinct by the end of the 19" century or beginning of the 20" century. In Canada, populations remained more stable but were still depleted from historical numbers. Overall population of the North American Beaver is estimated to have been 60-400 million before the arrival of Europeans. In the early 17" century, 50,000-80,000 beaver skins/year were exported from the eastern USA, which led to rapid decline in the population and fueled westward expansion of European interests in North America. Exploration of western North America was primarily the result of the search for fur, particularly beaver fur. By the mid-19"™ century in North America, up to 260,000 km? of wetlands were drained and converted to agriculture and other uses, which reduced available beaver habitat. Populations of North American Beavers are now stable or growing, and reintroduction efforts and a reduction in trapping pressure have allowed them to recolonize much,if not all, of their historical distribution in North America. Current population estimate in North America is 6-12 million beavers. In North America, beavers were primarily hunted and trapped for their fur, although castor sacs and castoreum were used for medicinal purposes in the past. Numerous place names that refer to beavers across North America and that the beaver is the one of the national animals of Canada attest to its importance to humans in North America. Increasing beaver populations across North America has increased the number of conflicts with humans. Dam construction and digging activities by beavers can damage human structures and influence land-use patterns. Loss of timber and agricultural land is occurring in areas where for centuries beavers were absent from the landscape. Impacts of increasing and spreading beaver populations on agriculture, other land uses, human structures, managed forests, roadways, road culverts, and railway beds, and how humans will learn to live with these impacts, are continuing concerns. Nevertheless, the successful return of the North American Beaver and its ability to increase and enhance wetland function represent a conservation success story. Human activity can still negatively impact the North American Beaver, especially because human use of water sources might not be compatible with sustainable beaver populations. Increased interest in use of fur on a global scale, primarily in China, might return beaver fur to a valuable economic resource in the future. Bibliography. Aleksiuk (1970), Baker & Hill (2003), Barisone et al. (2006), Basey (1999), Belovsky (1984), Bradt (1938), Brenner (1962), Brooks et al. (1980), Buech (1995), Busher (1975, 1980, 1991, 1996, 2007), Busher & Dzieciolowski (1999), Busher & Hartman (2009), Busher & Jenkins (1985), Busher & Lyons (1999), Busher et al. (1983), Chabreck (1958), Coles (1970), Crawford et al. (2009), Doucet & Fryxell (1993), Fryxell & Doucet (1993), Hall, E.R. & Kelson (1959), Hall, J.G. (1960), Hill (1982), Hodgdon (1978), Hodgdon & Lancia (1983), Hodgdon & Larson (1973), Jenkins (1975, 1981), Jenkins & Busher (1979), Korth (2001, 2008), Kuehn et al. (2000), Lancia (1979), Lancia & Hodgdon (1983), Larson & Gunson (1983), MacArthur (1989), McEwing et al. (2014), Miller Schwarze & Schulte (1999), MillerSchwarze & Sun Lixing (2003), Naiman & Melillo (1984), Naiman, Johnston & Kelley (1988), Naiman, Melillo & Hobbie (1986), Nixon & Ely (1969), Northcott (1971), Novakowski (1969), Osborn (1953), Patenaude & Bovet (1983), Potvin & Bovet (1975), Rosell & Schulte (2004), Rosell & Sun Lixing (1999), Schulte (1998), Schulte & Muller-Schwarze (1999), Schulte et al. (1995), Seton (1929), Shadle (1956), Stegeman (1954), Stephenson (1969), Sun Lixing & MillerSchwarze (1997 1998a, 1998b), Svendsen (1989), Taylor (1970), Tevis (1950), Townsend (1953), Warren (1927), Westbrook et al. (2006), Whitfield et al. (2015)., Published as part of Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Castoridae, pp. 150-168 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions on pages 167-168, DOI: 10.5281/zenodo.6584880

Family CASTORIDAE (BEAVERS) • Large, robust, semi-aquatic rodents with dorso-ventrally flattened tails about one-quarter of the total body length, small forelimbs, and webbed hindfeet. • 100-120 cm. • Palearctic and Nearctic Regions. • All types of freshwater wetlands from streams and ponds to large rivers and lakes. • 1 genus, 2 species, 2 taxa. • No species threatened; none Extinct since 1600., Published as part of Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Castoridae, pp. 150-168 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions on page 150, DOI: 10.5281/zenodo.6584880

In the context of the present monograph on the late Miocene vertebrate locality of Kucukcekmece, this paper aims to provide a detailed analysis of rodent, lagomorph and insectivore remains. The Kucukcekmece fauna includes three species of rodents (Byzantinia bayraktepensis Unay, 1980, Spalacidae indet. and Chalicomys jaegeri Kaup, 1832), one lagomorph (Ochotona ozansoyi Sen, 2003) and two insectivores (Schizogalerix sp. and Crusafontina cf. endemica Gibert, 1975). This assemblage is far from reflecting the complete spectrum of these groups in the community of the region. Several common late Miocene taxa are not represented in the material, which was collected by hand picking on the outcrops, not by screen washing of sediment. Among the species recovered, B. bayraktepensis and O. ozansoyi are known elsewhere in latest Astaracian (MN8) and early Vallesian (MN9) localities. The other taxa found at Kucukcekmece are common elements of European Vallesian faunas. Abundance of the beaver C. jaegeri sugge...