scholarly journals Exceptionally simple, rapidly replaced teeth in sauropod dinosaurs demonstrate a novel evolutionary strategy for herbivory in Late Jurassic ecosystems

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Keegan M. Melstrom ◽  
Luis M. Chiappe ◽  
Nathan D. Smith
Keyword(s):  
Late Jurassic ◽  
Evolutionary Strategy ◽  
Feeding Strategies ◽  
Tooth Replacement ◽  
Replacement Rate ◽  
Novel Approach ◽  
Terrestrial Environments ◽  
Dental Complexity

Abstract Background Dinosaurs dominated terrestrial environments for over 100 million years due in part to innovative feeding strategies. Although a range of dental adaptations was present in Late Jurassic dinosaurs, it is unclear whether dinosaur ecosystems exhibited patterns of tooth disparity and dietary correlation similar to those of modern amniotes, in which carnivores possess simple teeth and herbivores exhibit complex dentitions. To investigate these patterns, we quantified dental shape in Late Jurassic dinosaurs to test relationships between diet and dental complexity. Results Here, we show that Late Jurassic dinosaurs exhibited a disparity of dental complexities on par with those of modern saurians. Theropods possess relatively simple teeth, in spite of the range of morphologies tested, and is consistent with their inferred carnivorous habits. Ornithischians, in contrast, have complex dentitions, corresponding to herbivorous habits. The dentitions of macronarian sauropods are similar to some ornithischians and living herbivorous squamates but slightly more complex than other sauropods. In particular, all diplodocoid sauropods investigated possess remarkably simple teeth. The existence of simple teeth in diplodocoids, however, contrasts with the pattern observed in nearly all known herbivores (living or extinct). Conclusions Sauropod dinosaurs exhibit a novel approach to herbivory not yet observed in other amniotes. We demonstrate that sauropod tooth complexity is related to tooth replacement rate rather than diet, which contrasts with the results from mammals and saurians. This relationship is unique to the sauropod clade, with ornithischians and theropods displaying the patterns observed in other groups. The decoupling of herbivory and tooth complexity paired with a correlation between complexity and replacement rate demonstrates a novel evolutionary strategy for plant consumption in sauropod dinosaurs.

scholarly journals A review of the fossil record of non-baenid turtles of the clade Paracryptodira

2019 ◽  
Author(s):  
Walter G. Joyce ◽  
Jérémy Anquetin
Keyword(s):  
North America ◽  
Middle Jurassic ◽  
Fossil Record ◽  
Late Jurassic ◽  
Feeding Strategies ◽  
Aquatic Environments ◽  
Taxonomic Review ◽  
Nomina Invalida ◽  
Nomina Dubia

The fossil record of non-baenid paracryptodires ranges from the Late Jurassic (Kimmeridgian) tothe Paleocene of North America and Europe only. Earlier remains may be present as early as the Middle Jurassic (Bathonian). Only a single dispersal event is documented between the two continents following their breakup during the Cretaceous in the form of the appearance of the Compsemys lineage in the Paleocene of France. Non-baenid paracryptodires were restricted to freshwater aquatic environments, but display adaptations to diverse feeding strategies consistent with generalist, gape-and-suction, and hypercarnivorous feeding. Current phylogenies recognize two species rich subclades within Paracryptodira, Baenidae and Pleurosternidae, which jointly form the clade Baenoidea. A taxonomic review of non-baenid paracryptodires concludes that of 34 named taxa, 11 are nomina valida, 15 nomina invalida, and 8 nomina dubia.

scholarly journals A Novel Approach to Coordinating Green Wave System With Adaptation Evolutionary Strategy

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 214115-214127
Author(s):  
Ye Zheng ◽  
Renzhong Guo ◽  
Ding Ma ◽  
Zhigang Zhao ◽  
Xiaoming Li
Keyword(s):  
Evolutionary Strategy ◽  
Wave System ◽  
Novel Approach

scholarly journals Dental microwear texture reflects dietary tendencies in extant Lepidosauria despite their limited use of oral food processing

2019 ◽  
Vol 286 (1903) ◽  
pp. 20190544 ◽  
Author(s):  
Daniela E. Winkler ◽  
Ellen Schulz-Kornas ◽  
Thomas M. Kaiser ◽  
Thomas Tütken
Keyword(s):  
Surface Texture ◽  
Lower Surface ◽  
Feeding Strategies ◽  
Tooth Replacement ◽  
Dental Microwear ◽  
Subtle Discrimination ◽  
Texture Parameters ◽  
Broad Variety ◽  
Dental Surface ◽  
New Research

Lepidosauria show a large diversity in dietary adaptations, both among extant and extinct tetrapods. Unlike mammals, Lepidosauria do not engage in sophisticated mastication of their food and most species have continuous tooth replacement, further reducing the wear of individual teeth. However, dietary tendency estimation of extinct lepidosaurs usually rely on tooth shape and body size, which allows only for broad distinction between faunivores and herbivores. Microscopic wear features on teeth have long been successfully applied to reconstruct the diet of mammals and allow for subtle discrimination of feeding strategies and food abrasiveness. Here, we present, to our knowledge, the first detailed analysis of dental microwear texture on extant lepidosaurs using a combination of 46 surface texture parameters to establish a framework for dietary tendency estimation of fossil reptilian taxa. We measured dental surface textures of 77 specimens, belonging to herbivorous, algaevorous, frugivorous, carnivorous, ovivorous, insectivorous, molluscivorous, as well as omnivorous species. Carnivores show low density and shallow depth of furrows, whereas frugivores are characterized by the highest density of furrows. Molluscivores show the deepest wear features and highest roughness, herbivores have lower surface roughness and shallower furrows compared to insectivores and omnivores, which overlap in all parameters. Our study shows that despite short food–tooth interaction, dental surface texture parameters enable discrimination of several feeding strategies in lepidosaurs. This result opens new research avenues to assess diet in a broad variety of extant and extinct non-mammalian taxa including dinosaurs and early synapsids.

The dentition of the narrownose smooth-hound shark, Mustelus schmitti

2014 ◽  
Vol 65 (8) ◽  
pp. 688 ◽  
Author(s):  
Mauro Belleggia ◽  
Daniel E. Figueroa ◽  
Claudia Bremec
Keyword(s):  
Dental Formula ◽  
Tooth Replacement ◽  
Replacement Rate ◽  
Length Difference ◽  
Labial Side ◽  
Jaw Position ◽  
Established Technique ◽  
Trawl Surveys ◽  
Tooth Length ◽  
Mustelus Schmitti

The present study provides a quantitative and qualitative analysis on the dentition of Mustelus schmitti, and estimates the tooth-replacement rate. In total, 47 males and 56 females of M. schmitti were collected on scientific trawl surveys conducted by the National Institute of Fisheries Research and Development (INIDEP) in Argentina during the months of November 2007, November 2008 and December 2008. The dental laminas were extracted from the jaw cartilage and attached to onionskin paper for dehydration treatment, maintaining the original jaw position. Tooth replacement rate was estimated following established methods used for fossil sharks, instead of the established technique of clipping teeth, based on the premise that tooth length within each row decreases from the lingual to the labial side of the jaw as a consequence of wear. The length difference between consecutive teeth in four representative rows should be proportional to the tooth-replacement rate. Mustelus schmitti exhibited homodont dentition, where teeth were similar in shape or design, and are arranged in a semi-pavement-like dentition. The dental formula was 47-63/50-63 for juveniles and 50-77/50-69 for adult specimens. The estimated mean replacement rate was 4 days series–1.

scholarly journals Enamel formation and growth in non-mammalian cynodonts

2018 ◽  
Vol 5 (5) ◽  
pp. 172293 ◽  
Author(s):  
Rachel N. O'Meara ◽  
Wendy Dirks ◽  
Agustín G. Martinelli
Keyword(s):  
Growth Rates ◽  
Polarized Light ◽  
Growth Patterns ◽  
Juvenile Growth ◽  
Tooth Replacement ◽  
Replacement Rate ◽  
Adult Growth ◽  
Evolution Of Mammals ◽  
Additional Explanation ◽  
Incremental Lines

The early evolution of mammals is associated with the linked evolutionary origin of diphyodont tooth replacement, rapid juvenile growth and determinate adult growth. However, specific relationships among these characters during non-mammalian cynodont evolution require further exploration. Here, polarized light microscopy revealed incremental lines, resembling daily laminations of extant mammals, in histological sections of enamel in eight non-mammalian cynodont species. In the more basal non-probainognathian group, enamel extends extremely rapidly from cusp to cervix. By contrast, the enamel of mammaliamorphs is gradually accreted, with slow rates of crown extension, more typical of the majority of non-hypsodont crown mammals. These results are consistent with the reduction in dental replacement rate across the non-mammalian cynodont lineage, with greater rates of crown extension required in most non-probainognathians, and slower crown extension rates permitted in mammaliamorphs, which have reduced patterns of dental replacement in comparison with many non-probainognathians. The evolution of mammal-like growth patterns, with faster juvenile growth and more abruptly terminating adult growth, is linked with this reduction in dental replacement rates and may provide an additional explanation for the observed pattern in enamel growth rates. It is possible that the reduction in enamel extension rates in mammaliamorphs reflects an underlying reduction in skeletal growth rates at the time of postcanine formation, due to a more abruptly terminating pattern of adult growth in these more mammal-like, crownward species.

Bio-inspired graphene-coated ball screws: Novel approach to reduce the thermal deformation of ball screws

2020 ◽  
pp. 095440622093999
Author(s):  
Yueyang Guo ◽  
Xiangsheng Gao ◽  
Min Wang ◽  
Tao Zan
Keyword(s):  
Machine Tools ◽  
Thermal Deformation ◽  
Heat Dissipation ◽  
Radiative Heat ◽  
Test Bed ◽  
Element Analysis ◽  
Graphene Coating ◽  
Surrounding Environment ◽  
Novel Approach ◽  
Terrestrial Environments

To reduce the thermal deformation of ball screws, a novel approach inspired by silver ants is proposed. The Saharan silver ant maintains low body temperatures in one of the hottest terrestrial environments by radiating heat to the surrounding environment. Inspired by this, bio-inspired graphene-coated ball screws, which can enhance heat dissipation due to radiative heat dissipation of graphene coating, are designed to reduce the temperature and thermal deformation further. Finite element analysis is conducted to validate the excellent performance of the proposed bionic design in reducing thermal deformation. In order to verify the advantage of this method, comparative experiments between graphene-coated ball screws and the ordinary one are carried out on a self-designed test bed as well. The result shows that the bio-inspired design obviously reduced the temperature rise, thermal deformation, and temperature balance time. This bio-inspired approach will provide a new idea to solve the thermal issue of machine tools.

scholarly journals The moment of tooth: rate, fate and pattern of Pacific lingcod dentition revealed by pulse-chase

2021 ◽  
Vol 288 (1960) ◽  
Author(s):  
E. M. Carr ◽  
A. P. Summers ◽  
K. E. Cohen
Keyword(s):  
Tooth Replacement ◽  
Mineralized Tissue ◽  
Replacement Rate ◽  
Ophiodon Elongatus ◽  
Bony Fishes ◽  
Position Data ◽  
The Moment ◽  
Pharyngeal Jaw ◽  
Functional Position

Tooth replacement rates of polyphyodont cartilaginous and bony fishes are hard to determine because of a lack of obvious patterning and maintaining specimens long enough to observe replacement. Pulse-chase is a fluorescent technique that differentially colours developing mineralized tissue. We present in situ tooth replacement rate and position data for the oral and pharyngeal detentions of Ophiodon elongatus (Pacific lingcod). We assessed over 10 000 teeth, in 20 fish, and found a daily replacement rate of about two teeth (3.6% of the dentition). The average tooth is in the dental battery for 27 days. The replacement was higher in the lower pharyngeal jaw (LPJ). We found no difference between replacement rates of feeding and non-feeding fish, suggesting feeding was not a driver of tooth replacement. Lingcod teeth have both a size and location fate; smaller teeth at one spot will not grow into larger teeth, even if a large tooth nearby is lost. We also found increased rates of replacement at the posterior of the LPJ relative to the anterior. We propose that lingcod teeth do not migrate in the jaw as they develop; their teeth are fated in size and location, erupting in their functional position.

scholarly journals Relatively low tooth replacement rate in a sauropod dinosaur from the Early Cretaceous Ruyang Basin of central China

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12361
Author(s):  
Huali Chang ◽  
Hai-Lu You ◽  
Li Xu ◽  
Waisum Ma ◽  
Diansong Gao ◽  
...  
Keyword(s):  
Anatomical Study ◽  
Central China ◽  
Tooth Replacement ◽  
Replacement Rate ◽  
Tooth Formation ◽  
Single Crown ◽  
Feeding Mechanics ◽  
Data Points ◽  
Few Data ◽  
Rostral Portion

Tooth replacement rate is an important feature related to feeding mechanics and food choices for dinosaurs. However, only a few data points are available for sauropod dinosaurs, partially due to rarity of relevant fossil material. Four somphospondylan sauropod species have been recovered from the Lower Cretaceous Aptian–Albian Haoling Formation in the Ruyang Basin, Henan Province of central China, but no cranial material has been reported except for a single crown. Here we report the discovery of the rostral portion of a left dentary with replacement teeth in its first five alveoli. Comparative anatomical study shows the partial dentary can be assigned to a member of early diverging somphospondylans. The non-destructive tooth length-based approach to estimating tooth formation time and replacement rate is adopted here. The estimated tooth replacement rate is 76 days, faster than that of Brachiosaurus (83 days) and much lower than typical late diverging lithostrotian titanosaurians (20 days). Thus, this discovery adds an intermediate tooth replacement rate in the evolution of titanosauriform sauropods and supports the idea that evolution of tooth replacement rate is clade-specific. This discovery also provides more information to understand the Ruyang sauropod assemblage, which includes one of the most giant dinosaurs to have walked our Earth (Ruyangosaurus giganteus).

scholarly journals Sampling impacts the assessment of tooth growth and replacement rates in archosaurs: implications for paleontological studies

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9918
Author(s):  
Jens C.D. Kosch ◽  
Lindsay E. Zanno
Keyword(s):  
Dietary Habits ◽  
Small Sample ◽  
Formation Time ◽  
Alligator Mississippiensis ◽  
Central Axis ◽  
Tooth Replacement ◽  
Replacement Rate ◽  
Tooth Formation ◽  
Dental Tissues ◽  
Sampling Protocols

Dietary habits in extinct species cannot be directly observed; thus, in the absence of extraordinary evidence, they must be reconstructed with a combination of morphological proxies. Such proxies often include information on dental organization and function such as tooth formation time and tooth replacement rate. In extinct organisms, tooth formation times and tooth replacement rate are calculated, in part via extrapolation of the space between incremental lines in dental tissues representing daily growth (von Ebner Line Increment Width; VEIW). However, to date, little work has been conducted testing assumptions about the primary data underpinning these calculations, specifically, the potential impact of differential sampling and data extrapolation protocols. To address this, we tested a variety of intradental, intramandibular, and ontogentic sampling effects on calculations of mean VEIW, tooth formation times, and replacement rates using histological sections and CT reconstructions of a growth series of three specimens of the extant archosaurian Alligator mississippiensis. We find transect position within the tooth and transect orientation with respect to von Ebner lines to have the greatest impact on calculations of mean VEIW—a maximum number of VEIW measurements should be made as near to the central axis (CA) as possible. Measuring in regions away from the central axis can reduce mean VEIW by up to 36%, causing inflated calculations of tooth formation time. We find little demonstrable impact to calculations of mean VEIW from the practice of subsampling along a transect, or from using mean VEIW derived from one portion of the dentition to extrapolate for other regions of the dentition. Subsampling along transects contributes only minor variations in mean VEIW (<12%) that are dwarfed by the standard deviation (SD). Moreover, variation in VEIW with distance from the pulp cavity likely reflects idiosyncratic patterns related to life history, which are difficult to control for; however, we recommend increasing the number of VEIW measured to minimize this effect. Our data reveal only a weak correlation between mean VEIW and body length, suggesting minimal ontogenetic impacts. Finally, we provide a relative SD of mean VEIW for Alligator of 29.94%, which can be used by researchers to create data-driven error bars for tooth formation times and replacement rates in fossil taxa with small sample sizes. We caution that small differences in mean VEIW calculations resulting from non-standardized sampling protocols, especially in a comparative context, will produce inflated error in tooth formation time estimations that intensify with crown height. The same holds true for applications of our relative SD to calculations of tooth formation time in extinct taxa, which produce highly variable maximum and minimum estimates in large-toothed taxa (e.g., 718–1,331 days in Tyrannosaurus).

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