The lower incisor enamel microstructure of the fossil rodent family Eomyidae was believed to be t... more The lower incisor enamel microstructure of the fossil rodent family Eomyidae was believed to be three‐layered and highly derived but rather uniform throughout the clade. Here, we describe a new four‐layered schmelzmuster in Eomyidae consisting of a three‐fold portio interna with longitudinal oriented, uniserial Hunter‐Schreger bands and a one‐fold portio externa, accounting for a unique enamel microstructure character combination in Rodentia. This new schmelzmuster type has developed early in eomyid evolution and is detectable already in the late Eocene (Chadronian) of North America. In European eomyids, it first occurs in the early Miocene (MN 3), implying that this four‐layered schmelzmuster was not present in all members of the family but restricted to species included in Eomyini and some genera currently considered Eomyidae incertae sedis within Eomyidae. Additionally, our analysis recognizes three taxa with schmelzmuster divergent from all other eomyids. Incisor enamel microstr...
Recent innovations and cost reductions in photogrammetry-based 3D modeling have enabled museum vi... more Recent innovations and cost reductions in photogrammetry-based 3D modeling have enabled museum visitors to create 3D models based on photographs exhibited in galleries without breaking museum policies. While several museums make 3D museum data available on sharing platforms, museum visitors publish unofficial 3D data belonging to museum exhibits using a photogrammetry-based approach. This study shows that photogrammetry-based 3D models can be generated without breaking conventional photo policies (i.e., no use of flash and tripods) and that museum visitors can create commercial products based on these models. 3D models certainly enhance scientific value and promote broader and deeper interests in the natural sciences; however, the rights of owners of museum pieces are ambiguous with regard to the dissemination of unofficial data. This also makes information attributable to the original specimen unclear, which can potentially lead to revenue loss. We propose a set of best practices f...
Vertebrates developed tooth replacement over 400 million years ago. Then, 200 million years later... more Vertebrates developed tooth replacement over 400 million years ago. Then, 200 million years later, the combination of vertical tooth replacement with the thecodont implantation (teeth in bone sockets) appeared a key morphological innovation in mammalian evolution. However, we discovered that an extinct fish taxon, Serrasalmimus secans, showed the same innovation in the lineage Serrasalmimidae, which survived the end Cretaceous mass extinction event. The carnassial teeth are known in both mammals and pycnodont fish, but these teeth do not share the same tissues or developmental processes. Therefore, this serrasalmimid pycnodont fish might have independently acquired mammal-like tooth replacement and implantation, indicating that the fish and mammals convergently evolved the carnassial dental morphologies at about the same time, approximately 60 My ago, in separate ecosystems.
<p>(A) Ln(length*width of m1). Symbols in A: 13.8 to 13 Ma, inverted orange triangle for &l... more <p>(A) Ln(length*width of m1). Symbols in A: 13.8 to 13 Ma, inverted orange triangle for <i>Antemus chinjiensis</i>; 11.6 to 11.2 Ma, purple diamond for <i>Progonomys hussaini</i> +?<i>Karnimata</i> sp.; 10.5 to 10.1 Ma, blue cross for <i>Karnimata</i> sp. + <i>Progonomys</i> sp.; 8.8 Ma, green cross for morphotype 7; 7.8 Ma, green cross for morphotype 8; 7.4 Ma, light blue square for <i>Parapelomys</i> sp.; other symbols as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0069308#pone-0069308-g002" target="_blank">Figure 2</a>. (B) 20th percentile and 80th percentile of Ln(length*width of m1). (C) van Dam's <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0069308#pone.0069308-vanDam1" target="_blank">[30]</a> index of M1, calculated as tooth width divided by the distance (lap in figure) between the posterior side of the lingual anterocone and that of protocone. The vertical bar at 2.2 shows the lower boundary of VD index to be predominantly grazers. Symbols in C: 12.4 Ma, purple diamond for near <i>Progonomys</i> sp.; 11.6 to 11.2 Ma, purple diamond for <i>Progonomys hussaini</i>; 11.2 Ma, blue circle for ?<i>Karnimata</i> sp.; 10.5 and 10.1 Ma, blue circle for <i>Karnimata</i> sp., red triangle for <i>Progonomys</i> sp.; 8.8 and 8.2 Ma, blue circle for <i>Karnimata</i> sp. (+ large <i>Karnimata</i> sp.); other symbols as in A. (D) Hypsodonty of M1, calculated as crown height divided by length. Symbols as in C. Error bars indicate 95% bootstrap confidence intervals. Red dotted lines connect two reference points, and blue dotted lines are parallel to the red line and have one reference point.</p
A general lineage concept is widely adopted in studies of species delimitation for extant taxa wi... more A general lineage concept is widely adopted in studies of species delimitation for extant taxa with DNA sequence data. In the general lineage concept, species are separately evolving metapopulations that acquire sets of properties during the process of speciation. Murine rodents from the Miocene Siwalik Group of Pakistan have an excellent fossil record showing temporal trends of morphological change, and are therefore ideal to observe the process of lineage divergence as fossil evidence. Here, we review the evolution of Siwalik murine rodents in the sense of the general lineage concept and draw lines of evidence for lineage separation. For currently available datasets, we applied the initial split criterion as well as three operational criteria (phenetic, diagnosable and ecological properties). In early Siwalik murine rodents, the acquisition of distinct phenetic properties emerges subsequent to the event of the evolutionary split. The phenetic evidence occurs closer in time to ‘true’ divergence, while distinct diagnosable and ecological properties fully arise later. Within a sequence of time-controlled samples, these observations explicitly show that phenetic properties (here, shape data and a combination of linear measurements) more precisely delimit the divergence of fossil species than does the fixation of diagnostic properties.
Els Casots is one of the richest fossil vertebrate sites of the Vallès-Penedès Basin (Catalonia, ... more Els Casots is one of the richest fossil vertebrate sites of the Vallès-Penedès Basin (Catalonia, 89 Spain). It was discovered in and excavated briefly during the 1990s, resulting in the 90 recovery of thousands of remains and the erection of several new mammal species. 91 Excavations resumed in 2018 and continue to date. Here we provide updated results regarding 92 the age, stratigraphy, biota and palaeoenvironment of the site. The age of the site is well 93 constrained to ~15.9 Ma thanks to recent bio-and magnetostratigraphic data, thus coinciding 94 with the onset of the Miocene Climatic Optimum (MCO). The stratigraphic succession at the 95 site area indicates lacustrine to palustrine environments with cyclically oscillating water level. 96 There are several fossiliferous layers that have yielded a vertebrate fauna comprising up to 74 97 different vertebrate species including amphibians, reptiles, birds and mostly mammals. The 98 finding of several articulated partial skeletons indicate that the site records an autochthonous 99 to parautochthonous assemblage. The abundance and completeness of the vertebrate remains 100 together with a well-constrained age and detailed stratigraphic and palaeoenvironmental data, 101 make els Casots a key site for understanding wetland ecosystems in southern Europe during 102 the MCO.
Recent innovations and cost reductions in photogrammetry-based 3D modeling have enabled museum vi... more Recent innovations and cost reductions in photogrammetry-based 3D modeling have enabled museum visitors to create 3D models based on photographs exhibited in galleries without breaking museum policies. While several museums make 3D museum data available on sharing platforms, museum visitors publish unofficial 3D data belonging to museum exhibits using a photogrammetry-based approach. This study shows that photogrammetry-based 3D models can be generated without breaking conventional photo policies (i.e., no use of flash and tripods), and that museum visitors can create commercial products based on these models. 3D models can enhance the value of science and promote broader and deeper interests in the natural sciences. However, the rights of owners of museum pieces are ambiguous with regard to the dissemination of unofficial data, and this also makes information attributable to the original specimen unclear, which can potentially lead to revenue loss. We propose a set of best practice...
Abiotic forces, including climate change, continental drift, and geographic barriers, have been v... more Abiotic forces, including climate change, continental drift, and geographic barriers, have been viewed as the major driver of macroevolutionary change in organisms, evidenced by various studies from empirical, ecological, phylogenetic, and paleontological approaches on different time/spatial scales and resolutions. On the other hand, biotic interactions such as predator-prey interactions, interspecific competition for food, density-dependent natural selection has been limitedly recognized as a factor for shaping evolutionary patterns. In vertebrates, biotic interactions can be directly observable in field studies. However, the nature of long generation times in animals makes it difficult to obtain general patterns of biotic interactions apart from seasonal variations in the relatively short-term studies. In vertebrate paleontology, despite the advantage of the long-term time scales, possible morphological diversification and/or constraints due to the presence of competitors or compe...
Here, we report a new 'discovery' of a desmostylian fossil in the geological collection a... more Here, we report a new 'discovery' of a desmostylian fossil in the geological collection at a national university in Japan. This fossil was unearthed over 60 years ago and donated to the university. Owing to the original hand-written note kept with the fossil in combination with interview investigation, we were able to reach two equally possible fossil sites in the town of Tsuchiyu Onsen, Fukushima. Through the interviews, we learned that the fossil was discovered during construction of a debris flow barrier and that it was recognized as a 'dinosaur' bone among the locals and displayed in the Village Hall before/until the town experienced a fire disaster in 1954. As scientific findings, the fossil was identified to be a right femur of <i>Paleoparadoxia</i> (Desmostylia), which shows well-preserved muscle scars on the surface. The age was estimated to be 15.9 Ma or younger in zircon-dating. This study shows an excellent case that historical and scientific significances could be extracted from long-forgotten uncatalogued specimens as long as the original information is retained with the specimens.
Fossil records generally inform paleobiologists about extinct taxa and rates of evolution measure... more Fossil records generally inform paleobiologists about extinct taxa and rates of evolution measured at the scale of millions of years. Good records that are densely sampled through time can reveal species level details such as longevity in local sections. Yet fossil data normally do not address details of lineage microevolution because the density through time of lineage sampling is insufficient to perceive patterns at a precision finer than 106 years in most cases. This study concerns details of a splitting event in the evolution of murine rodents, an event for which multiple fossil samples dated to a precision of 105 years fortuitously document the tempo and mode of origin of sister species, the stems of two extant tribes of mice. Evolution of early Murinae in the northern part of the biogeographically restricted Indian subcontinent between 11.6 and 10.5 Ma involved cladogenesis of two crown taxa, the extant tribes Murini and Arvicanthini. Large samples of fossil rodent teeth docum...
Clozapine, an atypical antipsychotic agent, has been reported to cause acute hyperglycemia. Howev... more Clozapine, an atypical antipsychotic agent, has been reported to cause acute hyperglycemia. However, the mechanism of clozapine-induced rapidly developing hyperglycemia is not well elucidated. To clarify the mechanism underlying clozapine-induced acute hyperglycemia, we investigated the effects of single intravenous administration of clozapine on the serum concentrations of glucose and several endogenous substances in rats. Male Wistar rats received an intravenous injection of saline (control) or clozapine 2.5, 5, 10 mg/kg. Blood samples were obtained periodically after clozapine administration to determine the serum concentrations of glucose, adrenaline, glucagon, insulin, corticosterone, and clozapine. The serum concentrations of glucose, adrenaline, and glucagon increased dose-dependently after the administration of clozapine at 2.5-10 mg/kg, and reached maxima at 5 mg/kg of clozapine. The serum concentration of corticosterone increased after the administration of clozapine, but ...
Here, we report a new 'discovery' of a desmostylian fossil in the geological collection a... more Here, we report a new 'discovery' of a desmostylian fossil in the geological collection at a national university in Japan. This fossil was unearthed over 60 years ago and donated to the university. Owing to the original hand-written note kept with the fossil in combination with interview investigation, we were able to reach two equally possible fossil sites in the town of Tsuchiyu Onsen, Fukushima. Through the interviews, we learned that the fossil was discovered during construction of a debris flow barrier and that it was recognized as a 'dinosaur' bone among the locals and displayed in the Village Hall before/until the town experienced a fire disaster in 1954. As scientific findings, the fossil was identified to be a right femur of (Desmostylia), which shows well-preserved muscle scars on the surface. The age was estimated to be 15.9 Ma or younger in zircon-dating. This study shows an excellent case that historical and scientific significances could be extracted fr...
Rodents are the most speciose group of mammals and display a great ecological diversity. Despite ... more Rodents are the most speciose group of mammals and display a great ecological diversity. Despite the greater amount of ecomorphological information compiled for extant rodent species, studies usually lack of morphological data on dentition, which has led to difficulty in directly utilizing existing ecomorphological data of extant rodents for paleoecological reconstruction because teeth are the most common or often the only micromammal fossils. Here, we infer the environmental ranges of extinct rodent genera by extracting habitat information from extant relatives and linking it to extinct taxa based on the phenogram of the cluster analysis, in which variables are derived from the principal component analysis on outline shape of the upper first molars. This phenotypic “bracketing” approach is particularly useful in the study of the fossil record of small mammals, which is mostly represented by isolated teeth. As a case study, we utilize extinct genera of murines and non-arvicoline cri...
Murid rodents (Rodentia: Myomorpha: Muroidea: Muridae) represent the most diverse and abundant ma... more Murid rodents (Rodentia: Myomorpha: Muroidea: Muridae) represent the most diverse and abundant mammalian group. In this study, we reconstruct a dated phylogeny of the family using a multilocus dataset (six nuclear and nine mitochondrial gene fragments) encompassing 160 species representing 82 distinct murid genera from four extant subfamilies (Deomyinae, Gerbillinae, Lophiomyinae, and Murinae). In comparison with previous studies on murid or muroid rodents, our work stands out for the implementation of multiple fossil constraints within the Muridae thanks to a thorough review of the fossil record. Before being assigned to specific nodes of the phylogeny, all potential fossil constraints were carefully assessed; they were also subjected to several cross-validation analyses. The resulting phylogeny is consistent with previous phylogenetic studies on murids, and recovers the monophyly of all sampled murid subfamilies and tribes. Based on nine controlled fossil calibrations, our inferre...
Corrected placement of Mus-Rattus fossil calibration forces precision in the molecular tree of ro... more Corrected placement of Mus-Rattus fossil calibration forces precision in the molecular tree of rodents." Scientific Reports 5 (1): 14444.
In Asia, the first find of an eomyid rodent was reported almost one century after the first studi... more In Asia, the first find of an eomyid rodent was reported almost one century after the first studies of the family Eomyidae in North America and Europe. Since then, eomyid rodents have been increasingly found in Asia particularly over the past two decades. Here, we review the Asian record of this family at the genus level. Currently, 22 species within 14 genera were reported from Asia, including seven endemic genera and rare materials of apeomyine eomyids. Eomyids emphasize the palaeogeographic importance of Asia in considering intercontinental dispersal events of small mammals. With newly compiled data for Asian eomyids, we also compare genus-level diversity trends through time among North America, Europe, and Asia. Despite data standardizations limited with respect to potential biases in the fossil record, we found that the Asian eomyid diversity closely follows ecological shifts induced by climate changes. In general, Asian eomyid genera disappeared earlier than their European cou...
Fossil rodents are generally scarce in the Miocene of Japan. However, as much as three taxa of eo... more Fossil rodents are generally scarce in the Miocene of Japan. However, as much as three taxa of eomyid rodents had been reported from the early Miocene Nakamura Formation (ca. 18.5 Ma) in Gifu Prefecture, central Japan. In this study, we revisit one of them-the small-sized taxon-and assign this material to a new genus, Japaneomys, which is so far known only from the type locality. The new genus is closely related to but distinguished from Asianeomys, which is more widely distributed in Central and East Asia, by having: (i) more bunodont cheek teeth with lower lophids, yet complete transverse lophids; (ii) two-rooted p4; (iii) anterior lobe narrower than posterior lobe on m1, correspondingly synclinid I shorter and shallower than synclinid IV; (iv) hypolophid anteriorly concave on m1. Japaneomys shows a derived but peculiar four-layered enamel microstructure with longitudinally oriented Hunter-Schreger bands, compared to three-layered microstructure in typical eomyid rodents. A phylogenetic analysis indicates that Japaneomys is more basal than Asianeomys and likely diverged in the late Oligocene when Japan was still part of the eastern margin of continental Asia, suggesting that certain small mammal populations could have undergone allopatric speciation isolated from inner-continental regions of Asia.
The lower incisor enamel microstructure of the fossil rodent family Eomyidae was believed to be t... more The lower incisor enamel microstructure of the fossil rodent family Eomyidae was believed to be three‐layered and highly derived but rather uniform throughout the clade. Here, we describe a new four‐layered schmelzmuster in Eomyidae consisting of a three‐fold portio interna with longitudinal oriented, uniserial Hunter‐Schreger bands and a one‐fold portio externa, accounting for a unique enamel microstructure character combination in Rodentia. This new schmelzmuster type has developed early in eomyid evolution and is detectable already in the late Eocene (Chadronian) of North America. In European eomyids, it first occurs in the early Miocene (MN 3), implying that this four‐layered schmelzmuster was not present in all members of the family but restricted to species included in Eomyini and some genera currently considered Eomyidae incertae sedis within Eomyidae. Additionally, our analysis recognizes three taxa with schmelzmuster divergent from all other eomyids. Incisor enamel microstr...
Recent innovations and cost reductions in photogrammetry-based 3D modeling have enabled museum vi... more Recent innovations and cost reductions in photogrammetry-based 3D modeling have enabled museum visitors to create 3D models based on photographs exhibited in galleries without breaking museum policies. While several museums make 3D museum data available on sharing platforms, museum visitors publish unofficial 3D data belonging to museum exhibits using a photogrammetry-based approach. This study shows that photogrammetry-based 3D models can be generated without breaking conventional photo policies (i.e., no use of flash and tripods) and that museum visitors can create commercial products based on these models. 3D models certainly enhance scientific value and promote broader and deeper interests in the natural sciences; however, the rights of owners of museum pieces are ambiguous with regard to the dissemination of unofficial data. This also makes information attributable to the original specimen unclear, which can potentially lead to revenue loss. We propose a set of best practices f...
Vertebrates developed tooth replacement over 400 million years ago. Then, 200 million years later... more Vertebrates developed tooth replacement over 400 million years ago. Then, 200 million years later, the combination of vertical tooth replacement with the thecodont implantation (teeth in bone sockets) appeared a key morphological innovation in mammalian evolution. However, we discovered that an extinct fish taxon, Serrasalmimus secans, showed the same innovation in the lineage Serrasalmimidae, which survived the end Cretaceous mass extinction event. The carnassial teeth are known in both mammals and pycnodont fish, but these teeth do not share the same tissues or developmental processes. Therefore, this serrasalmimid pycnodont fish might have independently acquired mammal-like tooth replacement and implantation, indicating that the fish and mammals convergently evolved the carnassial dental morphologies at about the same time, approximately 60 My ago, in separate ecosystems.
<p>(A) Ln(length*width of m1). Symbols in A: 13.8 to 13 Ma, inverted orange triangle for &l... more <p>(A) Ln(length*width of m1). Symbols in A: 13.8 to 13 Ma, inverted orange triangle for <i>Antemus chinjiensis</i>; 11.6 to 11.2 Ma, purple diamond for <i>Progonomys hussaini</i> +?<i>Karnimata</i> sp.; 10.5 to 10.1 Ma, blue cross for <i>Karnimata</i> sp. + <i>Progonomys</i> sp.; 8.8 Ma, green cross for morphotype 7; 7.8 Ma, green cross for morphotype 8; 7.4 Ma, light blue square for <i>Parapelomys</i> sp.; other symbols as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0069308#pone-0069308-g002" target="_blank">Figure 2</a>. (B) 20th percentile and 80th percentile of Ln(length*width of m1). (C) van Dam's <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0069308#pone.0069308-vanDam1" target="_blank">[30]</a> index of M1, calculated as tooth width divided by the distance (lap in figure) between the posterior side of the lingual anterocone and that of protocone. The vertical bar at 2.2 shows the lower boundary of VD index to be predominantly grazers. Symbols in C: 12.4 Ma, purple diamond for near <i>Progonomys</i> sp.; 11.6 to 11.2 Ma, purple diamond for <i>Progonomys hussaini</i>; 11.2 Ma, blue circle for ?<i>Karnimata</i> sp.; 10.5 and 10.1 Ma, blue circle for <i>Karnimata</i> sp., red triangle for <i>Progonomys</i> sp.; 8.8 and 8.2 Ma, blue circle for <i>Karnimata</i> sp. (+ large <i>Karnimata</i> sp.); other symbols as in A. (D) Hypsodonty of M1, calculated as crown height divided by length. Symbols as in C. Error bars indicate 95% bootstrap confidence intervals. Red dotted lines connect two reference points, and blue dotted lines are parallel to the red line and have one reference point.</p
A general lineage concept is widely adopted in studies of species delimitation for extant taxa wi... more A general lineage concept is widely adopted in studies of species delimitation for extant taxa with DNA sequence data. In the general lineage concept, species are separately evolving metapopulations that acquire sets of properties during the process of speciation. Murine rodents from the Miocene Siwalik Group of Pakistan have an excellent fossil record showing temporal trends of morphological change, and are therefore ideal to observe the process of lineage divergence as fossil evidence. Here, we review the evolution of Siwalik murine rodents in the sense of the general lineage concept and draw lines of evidence for lineage separation. For currently available datasets, we applied the initial split criterion as well as three operational criteria (phenetic, diagnosable and ecological properties). In early Siwalik murine rodents, the acquisition of distinct phenetic properties emerges subsequent to the event of the evolutionary split. The phenetic evidence occurs closer in time to ‘true’ divergence, while distinct diagnosable and ecological properties fully arise later. Within a sequence of time-controlled samples, these observations explicitly show that phenetic properties (here, shape data and a combination of linear measurements) more precisely delimit the divergence of fossil species than does the fixation of diagnostic properties.
Els Casots is one of the richest fossil vertebrate sites of the Vallès-Penedès Basin (Catalonia, ... more Els Casots is one of the richest fossil vertebrate sites of the Vallès-Penedès Basin (Catalonia, 89 Spain). It was discovered in and excavated briefly during the 1990s, resulting in the 90 recovery of thousands of remains and the erection of several new mammal species. 91 Excavations resumed in 2018 and continue to date. Here we provide updated results regarding 92 the age, stratigraphy, biota and palaeoenvironment of the site. The age of the site is well 93 constrained to ~15.9 Ma thanks to recent bio-and magnetostratigraphic data, thus coinciding 94 with the onset of the Miocene Climatic Optimum (MCO). The stratigraphic succession at the 95 site area indicates lacustrine to palustrine environments with cyclically oscillating water level. 96 There are several fossiliferous layers that have yielded a vertebrate fauna comprising up to 74 97 different vertebrate species including amphibians, reptiles, birds and mostly mammals. The 98 finding of several articulated partial skeletons indicate that the site records an autochthonous 99 to parautochthonous assemblage. The abundance and completeness of the vertebrate remains 100 together with a well-constrained age and detailed stratigraphic and palaeoenvironmental data, 101 make els Casots a key site for understanding wetland ecosystems in southern Europe during 102 the MCO.
Recent innovations and cost reductions in photogrammetry-based 3D modeling have enabled museum vi... more Recent innovations and cost reductions in photogrammetry-based 3D modeling have enabled museum visitors to create 3D models based on photographs exhibited in galleries without breaking museum policies. While several museums make 3D museum data available on sharing platforms, museum visitors publish unofficial 3D data belonging to museum exhibits using a photogrammetry-based approach. This study shows that photogrammetry-based 3D models can be generated without breaking conventional photo policies (i.e., no use of flash and tripods), and that museum visitors can create commercial products based on these models. 3D models can enhance the value of science and promote broader and deeper interests in the natural sciences. However, the rights of owners of museum pieces are ambiguous with regard to the dissemination of unofficial data, and this also makes information attributable to the original specimen unclear, which can potentially lead to revenue loss. We propose a set of best practice...
Abiotic forces, including climate change, continental drift, and geographic barriers, have been v... more Abiotic forces, including climate change, continental drift, and geographic barriers, have been viewed as the major driver of macroevolutionary change in organisms, evidenced by various studies from empirical, ecological, phylogenetic, and paleontological approaches on different time/spatial scales and resolutions. On the other hand, biotic interactions such as predator-prey interactions, interspecific competition for food, density-dependent natural selection has been limitedly recognized as a factor for shaping evolutionary patterns. In vertebrates, biotic interactions can be directly observable in field studies. However, the nature of long generation times in animals makes it difficult to obtain general patterns of biotic interactions apart from seasonal variations in the relatively short-term studies. In vertebrate paleontology, despite the advantage of the long-term time scales, possible morphological diversification and/or constraints due to the presence of competitors or compe...
Here, we report a new 'discovery' of a desmostylian fossil in the geological collection a... more Here, we report a new 'discovery' of a desmostylian fossil in the geological collection at a national university in Japan. This fossil was unearthed over 60 years ago and donated to the university. Owing to the original hand-written note kept with the fossil in combination with interview investigation, we were able to reach two equally possible fossil sites in the town of Tsuchiyu Onsen, Fukushima. Through the interviews, we learned that the fossil was discovered during construction of a debris flow barrier and that it was recognized as a 'dinosaur' bone among the locals and displayed in the Village Hall before/until the town experienced a fire disaster in 1954. As scientific findings, the fossil was identified to be a right femur of <i>Paleoparadoxia</i> (Desmostylia), which shows well-preserved muscle scars on the surface. The age was estimated to be 15.9 Ma or younger in zircon-dating. This study shows an excellent case that historical and scientific significances could be extracted from long-forgotten uncatalogued specimens as long as the original information is retained with the specimens.
Fossil records generally inform paleobiologists about extinct taxa and rates of evolution measure... more Fossil records generally inform paleobiologists about extinct taxa and rates of evolution measured at the scale of millions of years. Good records that are densely sampled through time can reveal species level details such as longevity in local sections. Yet fossil data normally do not address details of lineage microevolution because the density through time of lineage sampling is insufficient to perceive patterns at a precision finer than 106 years in most cases. This study concerns details of a splitting event in the evolution of murine rodents, an event for which multiple fossil samples dated to a precision of 105 years fortuitously document the tempo and mode of origin of sister species, the stems of two extant tribes of mice. Evolution of early Murinae in the northern part of the biogeographically restricted Indian subcontinent between 11.6 and 10.5 Ma involved cladogenesis of two crown taxa, the extant tribes Murini and Arvicanthini. Large samples of fossil rodent teeth docum...
Clozapine, an atypical antipsychotic agent, has been reported to cause acute hyperglycemia. Howev... more Clozapine, an atypical antipsychotic agent, has been reported to cause acute hyperglycemia. However, the mechanism of clozapine-induced rapidly developing hyperglycemia is not well elucidated. To clarify the mechanism underlying clozapine-induced acute hyperglycemia, we investigated the effects of single intravenous administration of clozapine on the serum concentrations of glucose and several endogenous substances in rats. Male Wistar rats received an intravenous injection of saline (control) or clozapine 2.5, 5, 10 mg/kg. Blood samples were obtained periodically after clozapine administration to determine the serum concentrations of glucose, adrenaline, glucagon, insulin, corticosterone, and clozapine. The serum concentrations of glucose, adrenaline, and glucagon increased dose-dependently after the administration of clozapine at 2.5-10 mg/kg, and reached maxima at 5 mg/kg of clozapine. The serum concentration of corticosterone increased after the administration of clozapine, but ...
Here, we report a new 'discovery' of a desmostylian fossil in the geological collection a... more Here, we report a new 'discovery' of a desmostylian fossil in the geological collection at a national university in Japan. This fossil was unearthed over 60 years ago and donated to the university. Owing to the original hand-written note kept with the fossil in combination with interview investigation, we were able to reach two equally possible fossil sites in the town of Tsuchiyu Onsen, Fukushima. Through the interviews, we learned that the fossil was discovered during construction of a debris flow barrier and that it was recognized as a 'dinosaur' bone among the locals and displayed in the Village Hall before/until the town experienced a fire disaster in 1954. As scientific findings, the fossil was identified to be a right femur of (Desmostylia), which shows well-preserved muscle scars on the surface. The age was estimated to be 15.9 Ma or younger in zircon-dating. This study shows an excellent case that historical and scientific significances could be extracted fr...
Rodents are the most speciose group of mammals and display a great ecological diversity. Despite ... more Rodents are the most speciose group of mammals and display a great ecological diversity. Despite the greater amount of ecomorphological information compiled for extant rodent species, studies usually lack of morphological data on dentition, which has led to difficulty in directly utilizing existing ecomorphological data of extant rodents for paleoecological reconstruction because teeth are the most common or often the only micromammal fossils. Here, we infer the environmental ranges of extinct rodent genera by extracting habitat information from extant relatives and linking it to extinct taxa based on the phenogram of the cluster analysis, in which variables are derived from the principal component analysis on outline shape of the upper first molars. This phenotypic “bracketing” approach is particularly useful in the study of the fossil record of small mammals, which is mostly represented by isolated teeth. As a case study, we utilize extinct genera of murines and non-arvicoline cri...
Murid rodents (Rodentia: Myomorpha: Muroidea: Muridae) represent the most diverse and abundant ma... more Murid rodents (Rodentia: Myomorpha: Muroidea: Muridae) represent the most diverse and abundant mammalian group. In this study, we reconstruct a dated phylogeny of the family using a multilocus dataset (six nuclear and nine mitochondrial gene fragments) encompassing 160 species representing 82 distinct murid genera from four extant subfamilies (Deomyinae, Gerbillinae, Lophiomyinae, and Murinae). In comparison with previous studies on murid or muroid rodents, our work stands out for the implementation of multiple fossil constraints within the Muridae thanks to a thorough review of the fossil record. Before being assigned to specific nodes of the phylogeny, all potential fossil constraints were carefully assessed; they were also subjected to several cross-validation analyses. The resulting phylogeny is consistent with previous phylogenetic studies on murids, and recovers the monophyly of all sampled murid subfamilies and tribes. Based on nine controlled fossil calibrations, our inferre...
Corrected placement of Mus-Rattus fossil calibration forces precision in the molecular tree of ro... more Corrected placement of Mus-Rattus fossil calibration forces precision in the molecular tree of rodents." Scientific Reports 5 (1): 14444.
In Asia, the first find of an eomyid rodent was reported almost one century after the first studi... more In Asia, the first find of an eomyid rodent was reported almost one century after the first studies of the family Eomyidae in North America and Europe. Since then, eomyid rodents have been increasingly found in Asia particularly over the past two decades. Here, we review the Asian record of this family at the genus level. Currently, 22 species within 14 genera were reported from Asia, including seven endemic genera and rare materials of apeomyine eomyids. Eomyids emphasize the palaeogeographic importance of Asia in considering intercontinental dispersal events of small mammals. With newly compiled data for Asian eomyids, we also compare genus-level diversity trends through time among North America, Europe, and Asia. Despite data standardizations limited with respect to potential biases in the fossil record, we found that the Asian eomyid diversity closely follows ecological shifts induced by climate changes. In general, Asian eomyid genera disappeared earlier than their European cou...
Fossil rodents are generally scarce in the Miocene of Japan. However, as much as three taxa of eo... more Fossil rodents are generally scarce in the Miocene of Japan. However, as much as three taxa of eomyid rodents had been reported from the early Miocene Nakamura Formation (ca. 18.5 Ma) in Gifu Prefecture, central Japan. In this study, we revisit one of them-the small-sized taxon-and assign this material to a new genus, Japaneomys, which is so far known only from the type locality. The new genus is closely related to but distinguished from Asianeomys, which is more widely distributed in Central and East Asia, by having: (i) more bunodont cheek teeth with lower lophids, yet complete transverse lophids; (ii) two-rooted p4; (iii) anterior lobe narrower than posterior lobe on m1, correspondingly synclinid I shorter and shallower than synclinid IV; (iv) hypolophid anteriorly concave on m1. Japaneomys shows a derived but peculiar four-layered enamel microstructure with longitudinally oriented Hunter-Schreger bands, compared to three-layered microstructure in typical eomyid rodents. A phylogenetic analysis indicates that Japaneomys is more basal than Asianeomys and likely diverged in the late Oligocene when Japan was still part of the eastern margin of continental Asia, suggesting that certain small mammal populations could have undergone allopatric speciation isolated from inner-continental regions of Asia.
WINDOWS INTO SAUROPSID AND SYNAPSID EVOLUTION, 2023
Louis L. Jacobs developed the outlines of murine evolution through original fieldwork in the Siwa... more Louis L. Jacobs developed the outlines of murine evolution through original fieldwork in the Siwalik Hills of the Potwar Plateau in northern Pakistan. His discovery of middle Miocene age Antemus, an early stem murine, unveiled the roots of the modern mouse radiation of the later Miocene. He developed a hypothesis on the early late Miocene divergence of extant murine lineages, and included fossil Progonomys in the modern Mus lineage. A younger Miocene Siwalik locality produced a species close to the living house mouse. Louis named it Mus auctor and, as an early record of ~6.5 Ma on the present time scale, it seemed to define the emergence of modern mice. Since then, we have explored more thoroughly the Siwalik sequence and studied its series of rodent assemblages, including newer collections that antedate Mus auctor. We were surprised to discover a very small species of Mus older than Mus auctor and falling into the interval of 7.2 to 8.0 Ma. Morphometric analysis established it as a member of the modern genus and, although preceding Mus auctor, the new species proved more derived in some characters. Jacobs’ hypotheses that Progonomys is in the Mus lineage and that Mus auctor is readily transformed from Progonomys appear to be validated. However, before Mus auctor was in place, a derived species of Mus, formally named here, was present on the Potwar Plateau. The center of evolution of the genus Mus was likely in southeastern Asia, and from time to time the Potwar Plateau sampled the periphery of that evolution. It is Jacobs’ vision that led to this discovery, and we take this opportunity to explore in his honor the phylogenetic context of this new species.
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Papers by Yuri Kimura
the Potwar Plateau in northern Pakistan. His discovery of middle Miocene age Antemus, an early stem murine, unveiled the
roots of the modern mouse radiation of the later Miocene. He developed a hypothesis on the early late Miocene divergence of
extant murine lineages, and included fossil Progonomys in the modern Mus lineage. A younger Miocene Siwalik locality produced
a species close to the living house mouse. Louis named it Mus auctor and, as an early record of ~6.5 Ma on the present
time scale, it seemed to define the emergence of modern mice. Since then, we have explored more thoroughly the Siwalik
sequence and studied its series of rodent assemblages, including newer collections that antedate Mus auctor. We were surprised
to discover a very small species of Mus older than Mus auctor and falling into the interval of 7.2 to 8.0 Ma. Morphometric
analysis established it as a member of the modern genus and, although preceding Mus auctor, the new species proved more
derived in some characters. Jacobs’ hypotheses that Progonomys is in the Mus lineage and that Mus auctor is readily transformed
from Progonomys appear to be validated. However, before Mus auctor was in place, a derived species of Mus, formally
named here, was present on the Potwar Plateau. The center of evolution of the genus Mus was likely in southeastern Asia, and
from time to time the Potwar Plateau sampled the periphery of that evolution. It is Jacobs’ vision that led to this discovery, and
we take this opportunity to explore in his honor the phylogenetic context of this new species.