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Large-sized species of Ctenodactylidae from the Valley of Lakes (Mongolia): An update on dental morphology, biostratigraphy, and paleobiogeography

Adriana Oliver and Gudrun Daxner-Höck

Plain Language Abstract

We have studied three species of rodents from Mongolia Yindirtemys deflexus, Yindirtemys suni and Yindirtemys birgeri. They differ by size and morphology of the teeth. Yindirtemys suni is the largest and the youngest and ranges from Mongolia to China. Yindirtemys birgeri is the smallest and co-exists in Mongolia with Yindirtemys deflexus. The most abundant species is Y. deflexus and it is distributed through Kazakhstan, Mongolia, Inner Mongolia and North China. Both species, Yindirtemys deflexus and Yindirtemys suni, are the "key fossil" through which the age of the localities could be established.

The genus Yindirtemys was very abundant and diverse in Asia. Six small-sized species, three medium sized and two large-sized species occurred during the Oligocene (~34-23.5 million years) and early Miocene (~23.5-20 million years) in China, Mongolia and Kazakhstan. This suggests that no physical barriers existed between these countries.

Resumen en Español

Especies de gran tamaño de Ctenodactylidae del Valle de los Lagos (Mongolia): una actualización de la morfología dental, la bioestratigrafía y la paleobiogeografía

Nuestro estudio de las especies grandes y medianas del género Yindirtemys del Valle de los Lagos en Mongolia condujo al reconocimiento de tres especies: Yindirtemys deflexus, Y. suni y Y. birgeri. Difieren en el tamaño y la morfología dental. Yindirtemys suni es la más grande y Y. birgeri es la especie más pequeña. Yindirtemys deflexus y Y. suni aumentan en tamaño corporal pero no cambian la morfología dental dentro de su rango temporal. La especie de tamaño medio Yindirtemys birgeri se encuentra en Mongolia junto con Y. deflexus durante el Oligoceno tardío (biozona C1) y es la presencia conjunta más oriental de las especies hasta el momento. Hasta ahora, Y. birgeri se había encontrado únicamente en la región de Aral en Kazajstán. Tanto Yindirtemys deflexus como Y. suni se utilizan como marcadores bioestratigráficos. Yindirtemys deflexus es un "fósil guía" de la Edad de los Mamíferos Terrestres de China "Tabenbulukian" y para la biozona C1 en Mongolia; esta última se correlaciona con el Oligoceno. Yindirtemys suni es uno de los "fósiles guía" de la Edad de los Mamíferos Terrestres de China "Xiejian". En Mongolia, la especie abarca desde la transición Oligoceno-Mioceno (biozona C1-D) hasta el Mioceno más temprano (biozona D). La amplia gama geográfica de Yindirtemys en el Oligoceno de Asia sugiere que ninguna barrera física importante obstaculizó la distribución de mamíferos entre Kazajstán, Mongolia y el norte de China, pero las condiciones paleoecológicas y climáticas locales podrían haber influido en las estructuras comunitarias de mamíferos en estas áreas.

Palabras clave: Pequeños mamíferos; Yindirtemys; Asia; Paleógeno; Oligoceno; Mioceno

Traducción: Enrique Peñalver (Sociedad Española de Paleontología)

Résumé en Français

Nouvelles données sur la morphologie dentaire, la biostratigraphie, et la paléobiogéographie des espèces de Ctenodactylidae de grande taille de la vallée des Lacs (Mongolie)

Notre étude sur les espèces de Yindirtemys de moyenne et grande tailles de la vallée des Lacs en Mongolie a reconnu trois espèces : Yindirtemys deflexus, Y. suni, et Y. birgeri. Elles différent par leur taille et leur morphologie dentaire. Yindirtemys suni est l'espèce la plus grande et Y. birgeri la plus petite. Yindirtemys deflexus et Y. suni augmentent de taille corporelle au cours du temps mais ne changent pas de morphologie dentaire. Yindirtemys birgeri, de taille moyenne, coexiste en Mongolie avec Y. deflexus pendant l'Oligocène récent (biozone C1) et l'occurrence décrite ici est la plus orientale d'Y. birgeri. Jusqu'à maintenant, l'espèce Y. birgeri n'était connue que dans la région d'Aral au Kazakhstan. Yindirtemys deflexus et Y. suni sont tous les deux utilisés comme marqueurs biostratigraphiques. Yindirtemys deflexus est un « fossile clé » du Tabenbulukian (échelle des âges des mammifères terrestres chinois) et de la biozone mongole C1. Cette dernière est corrélée avec l'Oligocène. Yindirtemys suni est un des « fossiles clés » du Xiejian (échelle des âges des mammifères terrestres chinois). En Mongolie, l'espèce s'étend de la transition Oligocène-Miocène (biozone C1-D) au Miocène basal (biozone D). La distribution géographique très vaste de Yindirtemys à l'Oligocène en Asie suggère l'absence de barrières physiques majeures empêchant la dispersion des mammifères entre le Kazakhstan, la Mongolie, et le nord de la Chine, mais des conditions paléoécologiques et climatiques locales ont pu influencer la structure des communautés mammaliennes de ces régions.
Mots-clés : petits mammifères ; Yindirtemys ; Asie ; Paléogène ; Oligocène ; Miocène

Translator: Antoine Souron

Deutsche Zusammenfassung

Die großwüchsigen Ctenodacylidae-Arten aus dem Tal der Gobiseen (Mongolei): Zahnmorphologie, Biostratigraphie und Paläobiogeographie auf dem neuesten Stand.

Unsere Bearbeitung von großen und mittelgroßen Arten der Gattung Yindirtemys aus dem Tal der Gobiseen in der Mongolei umfasst drei Arten: Yindirtemys deflexus, Y. suni und Y. birgeri. Sie unterscheiden sich in Größe und Morphologie der Zähne. Yindirtemys suni ist die größte und Y. birgeri die kleinste Art. Yindirtemys deflexus und Y. suni nehmen im Verlauf ihrer Entwicklungszeit an Körpergröße zu, die Zahnmorphologie ändert sich dagegen nicht. In der Mongolei kommt die mittelgroße Art Y. birgeri gemeinsam mit Y. deflexus im Ober-Oligozän (Biozone C1) vor. Das ist das östlichste Vorkommen der Art, denn Y. birgeri war bisher nur von der Aral Region in Kasachstan bekannt. Yindirtemys deflexus und Y. suni werden in der Biostratigraphie als Leitfossilien eingesetzt. Yindirtemys deflexus zeigt das Chinesische Land-Säugetier-Alter „Tabenbulukian" und die Mongolische Biozonen C1 und C1-D an, die mit dem obersten Oligozän korrelieren. Y. suni ist Leitfossil für das Chinesische Land-Säugetier-Alter „Xiejian". In der Mongolei kommt die Art von der Oligozän-Miozän-Wende (Biozone C1-D) bis ins Unter-Miozän (Biozone D) vor. Yindirtemys war im Oligozän von Kasachstan, über die Mongolei bis nach China verbreitet, ein Hinweis darauf, dass keine physischen Barrieren ihre Ausbreitung über weite Teile Asiens verhinderten. Die vorhandenen Unterschiede der Säugetier-Gruppierungen dieser Regionen werden auf lokale klimatische und ökologische Bedingungen zurückgeführt.

Schlüsselwörter: Kleinsäuger; Yindirtemys; Asien; Paläogen; Oligozän; Miozän

Translator: Eva Gebauer

Arabic

Translator: Ashraf M.T. Elewa

 

 

FIGURE 1. Map of Mongolia, showing the location of the working area in the Valley of Lakes (Modified from Map of Mongolia by Cartography Co. Ltd, Ulan Bator, Mongolia).

figure1 

FIGURE 2. Dental terminology of the upper and lower cheek teeth of Yindirtemys deflexus. Terminology after Vianey-Liaud et al. (2006) and Wang (1997). Illustration modified from Schmidt-Kittler et al. (2007).

figure2 

FIGURE 3. Stratigraphic ranges of the Yindirtemys species from the Valley of Lakes (Mongolia). Stratigraphic chart (modified from Daxner-Höck et al., 2015) including the geological time scale (Gradstein et al., 2004), basalt ages and Mongolian biozones A - D (Höck et al., 1999), the lower boundary of the Xiejian Chinese Mammal Age after Meng et al. (2006).

 figure3

FIGURE 4. Upper molars of Yindirtemys deflexus from the Valley of Lakes (Mongolia). Nos. 1-18. From Loh: 1) LOH-C/1-NHMW 2006./0083/0002 P4-M3 left; 2) LOH-C/1-NHMW 2006/0083/0007 M3 right. From Del: 3) DEL-B/12-NHMW 2006/0089/0006 M2 right; 4) DEL-B/12-NHMW 2006/0089/0033 M1 left. From Huch Teeg: 5) RHN-A/7-NHMW 2006/0090/0009 M3 right; 6) RHN-A/7-NHMW 2006/0090/0010 M3 left; 7) RHN-A/7-NHMW 2006/0090/0012 M3 left; 8) RHN-A/7-NHMW 2006/0090/0015 DP4 right; 9) RHN-A/7-NHMW 2006/0090/0039 P4 left; 10) RHN-A/7-NHMW 2006/0090/0045 P4 right; 11) RHN-A/7-NHMW 2006/0090/0047 P4 right; 12) RHN-A/7-NHMW 2006/0090/0052 M3 right; 13) RHN-A/7-NHMW 2006/0090/0053 M2 right. From Toglorhoi: 14) TGW-A/surface -NHMW 2006/0086/0005 Complete maxilla. From Tatal Gol: 15) TAT-043-NHMW 2012/0034/0005 M2-M3 right. From Huch Teeg: 16) RHN-023-NHMW 2012/0038/0014 M1 right. From Hotuliin Teeg: 17) HTSE-009+013-NHMW 2012/0039/0015 M2-M3 right; 18) HTE-057-NHMW 2012/0045/0002 DP4 left. All teeth same magnification. Scale bar equals 1 mm.

figure4 

FIGURE 5. Lower molars of Yindirtemys deflexus from the Valley of Lakes (Mongolia). Nos. 1-21. From Loh: 1) LOH-C/1-NHMW 2006/0083/0015 dp4 right. From Ikh Argalatyn Nuru: 2) IKH-A/5-NHMW 2009/0148/0011 m1 left. From Del: 3) DEL-B/12-NHMW 2006/0089/0001 m2-m3 left; 4) DEL-B/12-NHMW 2006/0089/0002 m3 right; 5) DEL-B/12-NHMW 2006/0089/0018 p4 right; 6) DEL-B/12-NHMW 2006./0089/0025 m2 left; 7) DEL-B/12-NHMW 2006/0089/00027 m3 left; 8) DEL-B/12-NHMW 2006/0089/0029 m3 left; 9) DEL-B/12-NHMW 2006/0089/0041 m3 right. From Huch Teeg: 10) RHN-A/7-NHMW 2006/0090/0001 p4-m3 left; 11) RHN-A/7-NHMW 2006/0090/0004 dp4 left; 12) RHN-A/7-NHMW 2006/0090/0005 p4 left; 13) RHN-A/7-NHMW 2006/0090/0019 p4 right; 14) RHN-A/7-NHMW 2006/0090/0021 dp4 right; 15) RHN-A/7- NHMW 2006/0090/0031 m2 right; 16) RHN-A/7- NHMW 2006/0090/0032 m3 right; 17) RHN-A/7-NHMW 2006/0090/0037 m2-m3 left. From Tatal Gol: 18) TAT-051/2-NHMW 2012/0035/0005 m1 right. From Huch Teeg: 19) RHN-023-NHMW 2012/0038/0023 m2 left; 20) RHN-023-NHMW 2012/0038/0027 m1 right. From Hotuliin Teeg: 21) HTSE-009+013-NHMW 2012/0039/0020 m1 left. All teeth same magnification. Scale bar: 1 mm.

figure5 

FIGURE 6. Yindirtemys suni from the Valley of Lakes (Mongolia). Nos. 1-12. From Hotuliin Teeg (south): 1) HTS-056/3-NHMW 2012/0047/0001 M2-M3 right. From Unkheltseg: 2) UNCH-A/4-NHMW 2006/0088/0001 dp4 right; 3) UNCH-A/4-NHMW 2006/0088/0003 M1 left. From Hotuliin Teeg (east): 4) HTE-009-NHMW2012/0033/0009 m3 left; 5) HTE-008-NHMW 2012/0032/0004 p4 right; 6) HTE-008-NHMW 2012/0032/0005 m2 right; 7) HTE-008-NHMW 2012/0032/0006 m3 left; 8) HTE-014-018-NHMW 2012/0031/0001 P4-M2 right; 9) HTE-014-018-NHMW 2012/0031/0002 M2 right; 10) HTE-014-018-NHMW 2012/0031/0003 M3 right; 11) HTE-014-018-NHMW 2012/0031/0006 M3 left; 12) HTE-014-018-NHMW 2012/0031/0009 m1-m3 left. All teeth same magnification. Scale bar equals 1 mm.

figure6 

FIGURE 7. Complete maxilla of Yindirtemys birgeri from the locality of Tatal Gol (TAT-051/2- NHMW 2012/0060/0001) in the Valley of Lakes (Mongolia). Nos. 1-8. 1) P4 left; 2) M1 left; 3) M2 left; 4) M3 left; 5) P4 right; 6) M1 right; 7) M2 right; 8) M3 right. All teeth same magnification. Scale bar equals 1 mm.

 

 

FIGURE 8. Distribution of the length and width ranges charts of the upper and lower dental elements for the three large-sized species of Yindirtemys from the Valley of Lakes.

figure8

 

 

 

TABLE 1. Abbreviations of mammal assemblages including the biozone, the section/fossil point and the locality name.

Assemblage/fossil layer Biozone Section/fossil point Locality name
LOH-C/1 C1 LOH-C Loh
IKH-A/5 C1 IKH-A Ikh Argalatyn Nuru
IKH-B/5 C1 IKH-B Ikh Argalatyn Nuru
DEL-B/12 C1 DEL-B Del
TGW-A/surface C1 TGW-A Toglorhoi
TGW-A/5 C1 TGW-A Toglorhoi
TGW-A/3+4 C1 TGW-A Toglorhoi
TGS/surface C1 TGS Toglorhoi (south)
TAT-W/top C1 TAT Tatatal Gol
TAT-043 C1 TAT-E Tatal Gol
TAT-051/2 C1 TAT Tatal Gol
TAT-052/1 C1 TAT Tatal Gol
TAT-042 C1 TAT Tatal Gol
TAT-E/22 C1 TAT-E Tatal Gol
TAT-E/27 C1 TAT-E Tatal Gol
TAT-E/32 C1-D TAT-E Tatal Gol
RHN-A/7 C1 RHN-A Huch Teeg
RHN-023 C1 RHN Huch Teeg
HTSE-009+013 C1 HTSE Hotuliin Teeg (southeast)
HTSE-009/1 C1 HTSE Hotuliin Teeg (southeast)
HTSE-009/2 C1 HTSE Hotuliin Teeg (southeast)
HTSE-009/3 C1 HTSE Hotuliin Teeg (southeast)
HTSE-010 C1 HTSE Hotuliin Teeg (southeast)
HTSE-013/5 C1 HTSE Hotuliin Teeg (southeast)
HTE-057 C1 HTE Hotuliin Teeg (east)
HTS-011/1 (=HTS-056/1+2) C1-D HTS Hotuliin Teeg (south)
HTS-012 (=HTS-056/3) C1-D HTS Hotuliin Teeg (south)
HTE-009 D HTE Hotuliin Teeg (east)
HTE-008 D HTE Hotuliin Teeg (east)
HTE-014-018 D HTE Hotuliin Teeg (east)
UNCH-A/3+4 D UNCH-A Unkheltseg

 

 

TABLE 2. Descriptive statistics of the upper molars of Yindirtemys deflexus from the Valley of Lakes (Mongolia). Abbreviations: T.N., total number of teeth; N., number of teeth measured; min, minimum; max, maximum, δ, standard deviation. For abbreviations of assemblages see Table 1.

        Length Width
  Locality Element T.N. N. min mean max σ N. min mean max σ
Yindirtemys deflexus HTE-057 DP4 2 1   3.33     1   2.33    
RHN-023 DP4 1           1   2.55    
RHN-A/7 DP4 1 1   3.43     1   2.54    
HTS-011/1+2 P4 4 1   2.86     1   3.49    
HTE-057 P4 1 1   2.83     1   3.62    
HTSE-013/5 P4 1 1   2.91     1   3.42    
HTSE-009+013 P4 7 6 2.55 2.87 3.27 0.300 7 3.07 3.37 3.74 0.290
RHN-023 P4 4 3 2.80 3.00 3.19   4 3.31 3.44 3.54 0.100
RHN-A/7 P4 12 9 2.85 3.10 3.30 0.160 9 3.26 3.66 3.94 0.200
TAT-043 P4 2 2 2.91   3.44   2 3.42   3.95  
TGW-A/5 P4 4 2 2.62   2.93   2 3.35   3.56  
TGW-A/surface P4 7 5 2.51 2.81 3.10 0.270 4 3.52 3.59 3.71 0.080
DEL-B/12 P4 3 1   2.68     1   3.45    
IKH-A/5 P4 1 1   2.76     1   3.42    
LOH-C/1 P4 4 4 3.11 3.24 3.42   4 3.61 3.77 3.92  
HTS-011/1+2 M1 2 1   3.93     1   2.77    
HTE-057 M1 2 2 .66   4.03   2 3.13   3.32  
HTSE-009+013 M1 6           1   2.97    
RHN-023 M1 8 5 3.57 3.76 3.99 0.170 5 2.98 3.24 3.48 0.210
RHN-A/7 M1 2           1   3.52    
TAT-E/22 M1 1 1   4.34     1   3.39    
TAT-043 M1 3 1   4.10     1   3.34    
TGW-A/surface M1 8 2 .63   3.64   2 3.13   3.37  
DEL-B/12 M1 5 1   3.73     2 3.31   3.40  
LOH-C/1 M1 2 1   4.52     1   3.52    
HTS-011/1+2 M2 3 2 3.99   4.05   3 3.13 3.27 3.34  
HTE-057 M2 2 2 3.99   5.08   2 3.32   4.01  
HTSE-010 M2 1 1   4.72     1   4.18    
HTSE-009+013 M2 5 4 4.24 4.41 4.50 0.120 5 3.71 3.83 3.98 0.130
RHN-023 M2 7 5 3.88 4.29 4.71 0.380 5 3.55 3.73 3.98 0.180
RHN-A/7 M2 6 3 4.65 4.68 4.71   4 3.74 4.01 4.27 0.240
TAT-052/1 M2 2 1   5.16     1   4.60    
TAT-043 M2 1 1   5.44     1   4.60    
TGW-A/5 M2 4 4 4.05 4.43 4.99 0.420 2 3.46   4.21  
TGW-A/surface M2 9 5 4.38 4.62 4.99 0.240 4 3.78 3.95 4.14 0.180
DEL-B/12 M2 10 4 4.12 4.29 4.41 0.120 3 3.31 3.70 3.91  
IKH-A/5 M2 5 3 4.46 4.60 4.73   2 3.87   4.15  
LOH-C/1 M2 1           1   5.16    
HTS-011/1+2 M3 2 1   5.04     1   4.89    
HTE-057 M3 2 1   5.15     1   4.50    
HTSE-009/1 M3 2 1   4.20              
HTSE-009+013 M3 9 9 4.51 4.91 5.84 0.430 8 4.18 4.43 4.83 0.200
RHN-023 M3 2 2 4.80   5.26   2 3.94   4.09  
RHN-A/7 M3 6 6 4.79 5.07 5.38 0.220 6 4.06 4.42 4.74 0.230
TAT-E/27 M3 1 1   5.44     1   4.36    
TAT-052/1 M3 2 2 4.75   5.81   2 4.52   4.85  
TAT-043 M3 3 3 5.19 5.45 5.70   3 4.45 4.69 4.82  
TGW-A/5 M3 2 2 4.69   4.87   2 3.94   4.03  
TGW-A/surface M3 6 4 4.48 4.58 4.68 0.090 4 4.01 4.06 4.11 0.040
DEL-B/12 M3 7 5 4.24 4.65 5.02 0.290 4 3.93 4.13 4.34 0.190
IKH-A/5 M3 2 2 4.69   4.95   2 3.92   4.40  
LOH-C/1 M3 4 3 5.11 5.26 5.57   3 4.30 4.54 4.68  

 

TABLE 3. Descriptive statistics of the lower molars of Yindirtemys deflexus from the Valley of Lakes (Mongolia). Abbreviations: T.N., total number of teeth; N., number of teeth measured; min, minimum; max, maximum, δ, standard deviation. For abbreviations of assemblages see Table 1.

        Length Width
  Locality Element T.N. N. min mean max σ N. min mean max σ
Yindirtemys deflexus RHN-A/7 dp4 3 2 3.16   3.52   2 1.87   2.03  
LOH-C/1 dp4 1 1   4.00     1   2.30    
HTS-011/1+2 p4 1 1   2.95     1   2.47    
HTSE-009/2 p4 2 1   2.64     2 2.32   2.53  
HTSE-009+013 p4 1 1   3.14     1   2.77    
RHN-023 p4 6 2 2.93   3.02   4 2.41 2.51 2.61 0.090
RHN-A/7 p4 6 3 2.89 2.95 3.00   5 2.25 2.44 2.73 0.180
TAT-052/1 p4 3           3 2.21 2.62 2.86  
TAT-051/2 p4 2 1   2.66     2 2.07   2.38  
TAT-043 p4 1 1   3.01     1   2.58    
TGW-A/5 p4 1           1   2.75    
TGW-A/surface p4 2           2 2.31   2.32  
DEL-B/12 p4 9 6 2.85 2.89 2.98 0.060 8 2.31 2.43 2.54 0.090
IKH-B/5 p4 2           1   2.66    
LOH-C/1 p4 2           1   2.61    
HTS-011/1+2 m1 3 1   4.01     2 2.61   2.75  
HTE-057 m1 1 1   3.66     1   2.53    
HTSE-009/2 m1 1 1   3.39     1   2.47    
HTSE-009+013 m1 4 2 3.96   4.19   2 2.85   2.87  
RHN-023 m1 5 4 3.72 4.01 4.34 0.270 4 2.58 2.79 3.07 0.230
RHN-A/7 m1 8 5 3.58 3.93 4.39 0.340 6 2.48 2.76 3.09 0.230
TAT-051/2 m1 2 1   3.46     2 2.21   2.57  
TAT-043 m1 1           1   3.03    
TAT-W/Top m1 2 1   4.20     1   2.95    
TGW-A/5 m1 1 1   4.83     1   3.15    
IKH-B/5 m1 2           2 3.79   3.97  
IKH-A/5 m1 1           1   2.62    
HTS-011/1+2 m2 1 1   4.47     1   3.23    
HTE-057 m2 4 1   5.48     3 3.52 3.70 4.05  
HTSE-009/2 m2 1 1   4.55     1 3.25   3.25  
HTSE-009+013 m2 7 3 4.74 5.01 5.30   5 3.31 3.57 3.80 0.220
RHN-023 m2 4 4 4.35 4.91 5.28 0.400 4 3.15 3.48 3.70 0.240
RHN-A/7 m2 13 8 4.55 4.97 5.37 0.240 11 3.03 3.53 3.93 0.260
TAT-052/1 m2 3           2 3.50   4.25  
TAT-051/2 m2 3 1   5.43     2 3.33   3.81  
TAT-043 m2 1           1   3.91    
TAT-W/Top m2 1           1   3.95    
TGS m2 1     5.25              
TGW-A/5 m2 3     5.55     3 4.04 4.08 4.13  
TGW-A/surface m2 2           1   3.39    
DEL-B/12 m2 6 4 4.74 4.95 5.43 0.320 5 3.08 3.39 3.70 0.240
IKH-B/5 m2 2           2 4.36   4.77  
IKH-A/5 m2 1           1   3.48    
LOH-C/1 m2 5     5.58     1   4.15    
HTS-011/1+2 m3 2 1   5.60     1   3.69    
HTE-057 m3 1 1   6.08     1   4.08    
HTSE-009/3 m3 1 1   5.36              
HTSE-009/2 m3 1 1   4.99     1   3.35    
HTSE-009+013 m3 2 2 5.52   5.69   2 3.59   3.89  
RHN-023 m3 3 1   6.35     2 3.91   4.16  
RHN-A/7 m3 9 6 5.90 6.20 6.45 0.210 7 3.76 3.99 4.27 0.160
TAT-051/2 m3 1           1   3.61    
TAT-043 m3 1 1   6.11     1   4.06    
DEL-B/12 m3 16 12 5.03 5.48 5.90 0.270 12 3.45 3.68 3.97 0.140
IKH-B/5 m3 2           1   5.11    
IKH-A/5 m3 3 1   5.02     3 3.25 3.51 3.76  
LOH-C/1 m3 5 2 6.16   6.73   3 4.27 4.49 4.62  

 

TABLE 4. Descriptive statistics of the upper and lower molars of Yindirtemys suni from the Valley of Lakes (Mongolia) and the holotype from the Xiejia Formation of Xiejia, Quinghai (IVPP V 5992). Abbreviations: T.N., total number of teeth; N., number of teeth measured; min, minimum; max, maximum, δ, standard deviation. For abbreviations of assemblages see Table 1.

        Length Width
  Locality Element T.N. N. min mean max σ N. min mean max σ
Yindirtemys suni HTE-14-18 P4 2 2 3.74   4.44   2 4.62   4.98  
HTE-008 2 2 3.63   3.87   2 4.42   4.65  
HTE-009 1 1   4.11     1   4.33    
IVPP V 5992 (Type)   1   3.16     1   3.45    
HTE-009 M1 3 1   4.65     1   4.24    
IVPP V 5992 (Type)   1   3.76     1   3.56    
HTE-14-18 M2 2 1   5.35     2 4.86   5.43  
HTE-009 4 3 5.74 5.87 6.01   3 4.87 5.12 5.33  
HTS-012 1 1   5.00              
IVPP V 5992 (Type)   1   5.15     1   4.30    
HTE-14-18 M3 4 4 5.66 6.32 7.11 0.610 4 4.85 5.35 5.81 0.510
HTE-008 2 2 6.24   6.27   2 5.64   5.92  
HTE-009 3 3 6.25 6.34 6.49   2 5.50   5.57  
HTS-012 1 1   4.96     1   4.79    
IVPP V 5992 (Type)   1   6.30     1   5.10    
HTE-14-18 dp4 1 1   4.14              
HTE-008 p4 1 1   3.78     1   3.19    
HTE-14-18 m1 3 2 5.07   5.43   2 3.67   3.99  
HTE-14-18 m2 3 2 6.57   6.60   2 5.07   5.08  
HTE-008 2 1   5.78     2 4.53   4.56  
HTE-14-18 m3 2 2 8.18   8.37   2 5.47   5.80  
HTE-008 1 1   6.21     1   4.58    
HTE-009 4 3 7.36 7.55 7.68   3 4.93 5.02 5.13  

 

TABLE 5. Descriptive statistics of the upper and lower molars of Yindirtemys birgeri from the Aral Formation (Kazakhstan) and the locality Tatal Gol (TAT-051/2; 2012/0060/0001) in the Valley of Lakes (Mongolia). Abbreviations: T.N., total number of teeth; N., number of teeth measured; min, minimum; max, maximum, δ, standard deviation. The data on Y. birgeri from the Aral Formation are from Bendukidze et al. (2009).

      Length Width
  Country Element N. min mean max σ N. min mean max σ
Yindirtemys birgeri   P4 6 2.3 2.47 2.5 0.08 6 2.75 2.9 3 0.12
  M1 3 2.87 2.96 3 0.08 3 2.37 2.42 2.5 0.07
  M2 6 3.5 3.59 3.7 0.08 6 2.87 3.14 3.37 0.19
Aral Formation M3 7 3.62 3.91 4.12 0.19 7 2.5 3.23 3.5 0.38
(Kazakhstan) p4 6 2.2 2.41 2.75 0.19 6 1.85 2.03 2.2 0.16
  m1 2 3.1 3.18 3.25 0.11 2 2 2.2 2.4 0.28
  m2 3 3.95 4.28 4.5 0.29 3 2.6 2.8 2.9 0.17
  m3 5 4.8 4.88 5 0.08 5 3 3.09 3.25 0.1
    P4 2 2.53   2.54   2 2.99   3.02  
TAT-051/2 Valley of Lakes M2 1   3.31     2 3.25   3.26  
2012/0060/0001 (Mongolia) M3 2 3.35   3.75   2 3.48   3.52  

 

TABLE 6. Statistical analyses of the lengths of the cheek teeth of Yindirtemys deflexus and Y. suni. Abbreviations: N, number of specimens; df, degree of freedom; df2W, degree of freedom of the denominator corrected for Welch’s test; p, significance value; df2B-F, degree of freedom of the denominator corrected for Brown-Forsythe’s test; t, T-student value; F, One-way ANOVA test. Significant differences in bold (α=0.05). All analyses use exclusively localities with sample sizes larger than four specimens.

    Y. deflexus Y. suni  Welch's test Brown-Forsythe's test Student's test ANOVA
Element N Locality df df2W p df2B-F p t p F p
m1 4 RHN-023   8         0.137 0.723    
5 RHN-A/7              
m2 4 RHN-023   15             0.046 0.956
8 RHN-A/7              
4 DEL-B/12              
m3 6 RHN-A/7   17         31.723 0.000    
12 DEL-B/12              
P4 6 HTSE-009+013                    
9 RHN-A/7   19             2.914 0.082
5 TGW-A/surface                    
M2 4 HTSE-009+013   4 8.230     0.428        
5 RHN-023          
4 TGW-A/5   0.280 9.854    
5 TGW-A/surface          
4 DEL-B/12          
M3 4   HTE-14-18 27             14.826 0.000
9 HTSE-009+013              
6 RHN-A/7              
4 TGW-A/surface              
5 DEL-B/12              

 

TABLE 7. Post hoc (Tukey’s-b) of the M3 of Yindirtemys deflexus and Y. suni. Significant differences are indicated in bold. The mean difference is significant at the 0.05 level.

  Localities   Mean difference
Tukey's-b.   HTE-14-18 -1.664
DEL-B/12 HTSE-009+013 -0.263
Y. deflexus RHN-A/7 -0.416
  TGW-A/surface 0.07525
  DEL-B/12 1.664
HTE-14-18 HTSE-009+013 1.401
Y. suni RHN-A/7 1,248
  TGW-A/surface 1.73925
  DEL-B/12 0.263
HTSE-009+013 HTE-14-18 -1.401
Y. deflexus RHN-A/7 -0.153
  TGW-A/surface 0.33825
  DEL-B/12 0.416
RHN-A/7 HTE-14-18 -1.248
Y. deflexus HTSE-009+013 0.153
  TGW-A/surface 0.49125
  DEL-B/12 -0.07525
TGW-A/surface HTE-14-18 -1.73925
Y. deflexus HTSE-009+013 -0.33825
  RHN-A/7 -0.49125
 

author1Adriana Oliver. Museo Nacional de Ciencias Naturales, MNCN-CSIC, C/ José Gutiérrez Abascal, 2, 28006, Madrid, Spain. Geological-Paleontological Department, Natural History Museum Vienna. Burgring 7, 1010 Vienna, Austria. This email address is being protected from spambots. You need JavaScript enabled to view it.

Adriana Oliver is a Ph.D. in Palaeontology by the University Complutense of Madrid (Spain). Her studies deal with the systematics, taxonomy, morphometry, paleoecology and evolution of rodents, both fossils (cricetids, ctenodactylids, glirids, sciurids) and extant groups (phyllotine cricetids), applying different analytical techniques (dental microwear analysis, classical and geometric morphometric analysis, confocal microscopy and CT-scan). She has focused on the Oligocene and Miocene rodents from Europe and Asia and on the biostratigraphy of those basins.

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author2Gudrun Daxner-Höck. Geological-Paleontological Department, Natural History Museum Vienna. Burgring 7, 1010 Vienna, Austria. This email address is being protected from spambots. You need JavaScript enabled to view it.

Gudrun Daxner–Höck, born 1941 in Steyregg, made her studies, Ph.D. thesis and habilitation at the University of Vienna, Austria. She was lecturer at the Universities of Salzburg, Vienna and Graz and curator of fossil vertebrates at the Natural History Museum Vienna, and is retired since 2007. She is a long time investigator of Oligocene and Miocene continental deposits of Mongolia and Austria, and leader of several scientific projects funded by the Austrian Science Fund FWF.

 

APPENDIX 1.

Distribution of character states (available online as PDF download).

.

APPENDIX 2.

Description of the character states (available online as PDF download).

 

APPENDIX 3.

Three dimensional figure of Yindirtemys birgeri from the locality of Tatal Gol (TAT-051/2), Valley of Lakes (Mongolia). Palate with P4-M3 left and P4-M3 right. NHMW 2012/0060/0001 (available online as PDF download).

appendix 3