New Yuomys rodents from southeastern Qinghai-Tibet Plateau indicate low elevation during the Middle Eocene

Yuomys are medium-sized Hystricomorpha rodents. They are known for coming from areas of low elevation in China during the middle and late Eocene. Two new Yuomys were discovered from a locality near Xueshuo village in Litang County, Sichuan Province. The locality lies in the Gemusi pull-apart basin formed in the Litang Fault System (LTFS) in the Hengduan Mountains. The current average elevation is about 4200 m. One of the two new Yuomys is larger and shows clear lophodont and unilateral hypsodont morphology, similar to Yuomys yunnanensis, which was discovered as being from the early middle Eocene (Irdinmanhan, Asian Land Mammal Ages) in the Chake Basin of Jianshui County, Yunnan Province. The Chake Basin is one of the small pull-apart basins formed in the Xianshuihe-Xiaojiang Fault system (XSH-XJF). The other new Yuomys rodent is smaller, brachydont, and less lophodont than the larger new species. The small new Yuomys is smaller than all known Yuomys except Yuomys huheboerhensis, which is from the early middle Eocene Irdinmanhan of Inner Mongolia in Northern China. Given their narrow biochronological distribution and presumably preferred living environment, the occurrence of Yuomys in the pull-apart basins in LTFS and XSH-XJF suggests that the two deep fault systems probably started strike-slip movement by the early middle Eocene, about 49–45 million years ago. Well-studied middle Eocene mammalian faunas from Henan and Inner Mongolia include Yuomys, primates, and other low elevation forest mammals. We suggest that the two new Yuomys species reported here probably also lived in a similar low elevation forest environment

Molecular and Paleontological Evidence for a Post-Cretaceous Origin of Rodents

The timing of the origin and diversification of rodents remains controversial, due to conflicting results from molecular clocks and paleontological data. The fossil record tends to support an early Cenozoic origin of crown-group rodents. In contrast, most molecular studies place the origin and initial diversification of crown-Rodentia deep in the Cretaceous, although some molecular analyses have recovered estimated divergence times that are more compatible with the fossil record. Here we attempt to resolve this conflict by carrying out a molecular clock investigation based on a nine-gene sequence dataset and a novel set of seven fossil constraints, including two new rodent records (the earliest known representatives of Cardiocraniinae and Dipodinae). Our results indicate that rodents originated around 61.7–62.4 Ma, shortly after the Cretaceous/Paleogene (K/Pg) boundary, and diversified at the intraordinal level around 57.7–58.9 Ma. These estimates are broadly consistent with the paleontological record, but challenge previous molecular studies that place the origin and early diversification of rodents in the Cretaceous. This study demonstrates that, with reliable fossil constraints, the incompatibility between paleontological and molecular estimates of rodent divergence times can be eliminated using currently available tools and genetic markers. Similar conflicts between molecular and paleontological evidence bedevil attempts to establish the origination times of other placental groups. The example of the present study suggests that more reliable fossil calibration points may represent the key to resolving these controversies.Organismic and Evolutionary Biolog

New material of alagomyids

29 p. : ill. ; 26 cm.Includes bibliographical references (p. 26-29).Newly discovered specimens of alagomyids, mostly isolated teeth collected by screenwashing at the Gashatan (late Paleocene) Subeng locality in Inner Mongolia, document considerable intraspecific variation in Tribosphenomys minutus that has not been appreciated previously because of limited sample sizes. P4s of Tribosphenomys are described for the first time, which helps to clarify the posterior premolar identification of alagomyids. Some of the alagomyid specimens are referred to Tribosphenomys cf. T. secundus and Neimengomys qii gen. and sp. nov. Based on the new data, Tribosphenomys borealis from the Bumban Member of the Naran Bulak Formation, Mongolia, is considered to be a junior synonym of Alagomys inopinatus, and T. tertius from the Zhigden Member of the Naran Bulak Formation is regarded as a junior synonymof T. minutus. Alagomyidae, consisting of Tribosphenomys, Alagomys and Neimengomys, is maintained as a valid family. The presence of a diversity of alagomyids and other recently obtained fossils and stratigraphic evidence from the Erlian Basin suggest that the Gashatan and Bumbanian of Asia are probably correlative to the late Tiffanian-early Wasachian of North America. The faunal turnover during the Gashatan and Bumbanian in Asia is probably related to the late Paleocene-early Eocene global warming, but current evidence is insufficient to link any specific event with the Paleocene-Eocene Thermal Maximum

Printability and Applicability of 3D Printing System Loaded with Chlorogenic Acid Hydrogel

Three-dimensional food printing (3DFP) is an efficient way of food processing in line with the future lifestyle. As a delivery system, hydrogel has become a research hotspot because of its remarkable characteristics such as directed delivery. The purpose of this study was to explore the effects of 3DFP on the structure, physical properties and functions of hydrogels containing methylcellulose (MC), chlorogenic acid (CA) and hyaluronic acid (HA) for the purpose of revealing the printability and applicability of hydrogels in 3DFP processing. Texture properties, rheological properties, microstructure, embedding rate and digestive properties of the 3D printed products were measured. The results showed that the best CA-loaded hydrogel system for 3DFP processing consisted of MC, HA and CA at a mass ratio of 8:0.5:0.5. Its printed product showed the smallest width deviation (13.40%), the highest hardness, the maximum elasticity, and the minimum adhesiveness, had compact structure and uniform porosity, was not easy to collapse, and had good supportability and the best printing moldability. 3DFP well optimized the physical structure of hydrogel without changing its chemical properties. The embedding rate of CA was 22.09 percentage points higher than that before 3D printing. In simulated gastrointestinal digestion test, the release rate of CA from the printed product was significantly higher than that of the unprinted samples, showing a good sustained release effect, and the in vitro release of CA was fitted to the Ritger-Peppas model. These results showed that the hydrogel system had good printability and applicability, and 3DFP could significantly improve the targeted release of CA loaded in hydrogel

A new glirid-like cricetid from the lower Oligocene of Southern China

Here we report a new cricetid s.l., Caecocricetodon yani, gen. et sp. nov., discovered in the early Oligocene of the Caijiachong Formation in Yunnan Province, China. The new cricetid differs from all known cricetids or stem muroids by its particular molar pattern displaying numerous crests and spurs. Our phylogenetic analysis based on a matrix including 42 taxa and 72 characters indicates that the new species has a close relationship with Paracricetodontinae, forming a monophyletic clade with Paracricetodon and Trakymys. The new cricetid also has a likely close relationship with Pappocricetodon. However, the genus Pappocricetodon is polyphyletic in our analysis. Considering the similarity of the brachydont lophodont teeth of Caecocricetodon and glirids, we propose that the new species underwent convergent evolution with dormice, possibly adapting to an arboreal ecological niche in Oligocene of southern China

Oldest ctenodactyloid tarsals from the Eocene of China and evolution of locomotor adaptations in early rodents

Abstract Background Tamquammys has been considered one of the basal ctenodactyloid rodents, which has been documented in the earliest to middle Eocene (~ 56.0–48.5 Ma) in China. It was the most abundant and widespread rodent genus in the Erlian Basin (Nei Mongol, China) and dominated Arshantan small-mammal faunas of that region. Here for the first time we describe the morphology of the astragalocalcaneal complex in Tamquammys robustus (larger) and T. wilsoni, and interpret it against the background of locomotor adaptations of basal Euarchontoglires (rodents, lagomorphs, tree shrews, and primates). Results The comparative morphology of the tarsal elements in Tamquammys robustus and T. wilsoni shows overall slenderness of the bones and their similarity to the tarsal elements of Rattus, a generalist species, and those of small rock squirrels (e.g. Sciurotamias). The two species differ slightly in their cursorial ability; smaller T. wilsoni shows some adaptations to climbing. The results of principal component analysis of the calcaneus and astragalus support this observation and place T. robustus in-between Rattus and ground/rock squirrel morphospace, and T. wilsoni closer to euarchontans, Tupaia and Purgatorius. Conclusions The morphology of the tarsal elements in Tamquammys indicates a generalist rodent morphotype with no particular adaptations to arboreality. We suggest that Tamquammys as a basal ctenodactyloid is closer to the ancestral astragalocalcaneal morphology of rodents than that of more derived North American paramyines of similar age. Overall similarity in Tamquammys tarsal elements structure to Purgatorius, a basal primate, may point to the antiquity of the tarsal structure in Tamquammys and a generally unspecialized foot structure in early Euarchontoglires

Propalaeocastor (Rodentia, Mammalia) from the Early Oligocene of Burqin Basin, Xinjiang

WU, WENYU, MENG, JIN, YE, JIE, NI, XIJUN (2004): Propalaeocastor (Rodentia, Mammalia) from the Early Oligocene of Burqin Basin, Xinjiang. American Museum Novitates 3461 (1): 1-16, DOI: 10.1206/0003-0082(2004)461<0001:PRMFTE>2.0.CO;2, URL: http://www.bioone.org/perlserv/?request=get-abstract&doi=10.1206%2F0003-0082(2004)461%3C0001%3APRMFTE%3E2.0.CO%3B

Prodistylomys wangae Bi & Meng & Wu & Ye & Ni 2009, n. sp.

Prodistylomys wangae, n. sp. Figure 8, table 1 HOLOTYPE: IVPP V16016.1, right fragmentary mandible with broken incisor and complete p4–m2. REFERRED MATERIAL: IVPP V 16016.2, right M3; V 16016.3, left fragmentary mandible with broken i2–p4, and m1–m2; V 16016.4, right fragmentary mandible with broken i2 and p4–m2; V 16016.5, left m1. LOCALITY AND AGE: Locality XJ200601 (47 ° 23.198 9 N, 86 ° 47.981 9 E) in Burqin County of Xinjiang, Suosuoquan Formation, early Miocene. ETYMOLOGY: The species name, wangae, is in honor of our colleague, Wang Banyue, for her contribution to the study of distylomyids. REPOSITORY: The specimens are stored in the collections of the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing. DIAGNOSIS: Slightly larger than P. lii and P. xinjiangensis. Differs from P. lii in having weak roots, thicker cement, rounded lingual apex of m1 trigonid, shorter talonid on m2. Differs from P. xinjiangensis in having thicker cement, rounded lingual apex of m1 trigonid, and the absence of the metaflexid on lower molars. DESCRIPTION: The M3 trigon is semicircular in outline, with a straight posterior margin (fig. 8A). The enamel is very thick, becoming thinner on the posterior margin. The hypoflexus extends to the base of the crown and becomes shallower while approaching the base. The mesoflexus extends L of the height of the crown and is fused toward the base, suggesting a rudimentary root. On the contrary, in P. lii, both flexi are fused, showing a well-developed root. The talon is circular shaped, much narrower than the trigon. The state of the masseteric crest is typical for the genus; the ventral crest is strong and extends under p4 and the dorsal crest is absent. The lower incisor extends posteriorly to underneath m3. The lower incisor is similar in its general morphology and microstructure to that of Distylomys burqinensis except that the pulp cavity is significantly smaller (fig. 5A, D). The p4 is shorter than m1 (fig. 8C). The trigonid is much narrower than the talonid compared with that in P. lii and P. xinjiangensis and has a stout anterolophid. The anterolophid is blunt and lies well toward the labial side of the tooth rather than in the center. Only thin cement is present in the flexids. The talonid has a vestigial posterolophid. Only m1 and m2 are preserved (fig. 8C; table 1). The lower molars are bilophodont, and hypsodont. The crown expands toward the base. The trigonid is subelliptical with a rounded anterior wall and a long axis oriented slightly anterolabial-posterolingually. The flexids are Ushaped with thin cement; the mesoflexid shallows but extends all the way to the base, and the hypoflexid extends down 2/3 of the height of the crown where it closes, indicating a rudimentary root (fig. 8B). The talonid is narrower than the trigonid, and is compressed with acute labial and lingual angles. The m1 and m2 are identical in crown morphology, but m2 is shorter than m1, and the lingual apex of its trigonid is more acute. COMMENT: Although the Xinjiang specimens are very similar to Distylomys in crown morphology, the rudimentary roots of the cheek teeth, shorter trigonid and narrower talonid on lower molars, and thinner cement suggest that it is better to assign the specimens to the genus Prodistylomys rather than to Distylomys. P. wangae differs substantially from P. lii in showing a tendency to the loss of roots and subelliptical trigonid. It differs from P. xinjiangensis in the absence of the posterolophid (or metaflexid) and subelliptical trigonid.Published as part of Bi, Shundong, Meng, Jin, Wu, Wenyu, Ye, Jie & Ni, Xijun, 2009, New Distylomyid Rodents (Mammalia: Rodentia) from the Early Miocene Suosuoquan Formation of Northern Xinjiang, China, pp. 1-20 in American Museum Novitates 3663 on page 13, DOI: 10.1206/665.1, http://zenodo.org/record/473550

Distylomys Wang 1988

Distylomys Wang, 1988 TYPE SPECIES: Distylomys tedfordi Wang, 1988. INCLUDED SPECIES: Distylomys qianlishanensis Wang, 1988; D. burqinensis, n. sp. GEOLOGICAL RANGE: Late Oligocene to middle Miocene. GEOGRAPHIC DISTRIBUTION: Inner Mongolia, Gansu, and Xinjiang, China. EMENDED DIAGNOSIS: Incisive foramen small; tooth rows convergent anteriorly; mental foramen in diastema; distinct ventral masseteric crest extending below p4; sciurognathous angular process; dental formula 1/1, 0/0, 1/1, 3/3; cheek teeth hypselodont with asymmetrical pattern; P4 nonmolariform; upper molars bilophodont without the mure; p4 molariform; lower molars bilophodont with the mure; mesoflexid and hypoflexid deep and wide, opposite to each other and with cement; worn occlusal surface of cheek teeth smoothly concave with enamel thin or interrupted at the posterior edge of teeth.Published as part of Bi, Shundong, Meng, Jin, Wu, Wenyu, Ye, Jie & Ni, Xijun, 2009, New Distylomyid Rodents (Mammalia: Rodentia) from the Early Miocene Suosuoquan Formation of Northern Xinjiang, China, pp. 1-20 in American Museum Novitates 3663 on page 4, DOI: 10.1206/665.1, http://zenodo.org/record/473550