Trilobites were one of the first animals on Earth to leave their imprints on the seafloor. Such imprints represent behavioral traces related to feeding or protection, in both cases implying different ...types of locomotion. Modeling how trilobites moved is essential to understand their evolutionary history and ecological impact on marine substrates. Herein, locomotion in trilobites is approached by means of three-dimensional models, which yielded two main gait types. These two gaits reflect basic behaviors: burrowing and walking. This model reveals that trilobites could change their gait and consequently increase rapidly their speed varying the amplitude of the metachronal wave, a change independent from their biological structure. Fast increases in speed enhanced the protection of trilobites against predators and sudden environmental crises. The trilobite body pattern constrained their gaits, controlled by the distance between the pair of legs and between legs in a same segment.
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•Kinematic models reflect two behaviors: burrowing and walking•Longitudinal amplitude and wave number control the gaits•Specific number of segments improves stabilization of gaits•Relationship between gaits and caudalization trends in trilobites
Wildlife behavior; Paleontology; Computational bioinformatics
Los trilobites del Cámbrico medio encontrados en Purujosa y otras localidades de las Cadenas Ibéricas como Murero y Mesones (Zaragoza) poseen un gran número de nuevas estructuras de enrollamiento, ...así como tipos de enrollamiento que previamente no se habían descrito en el Cámbrico, mostrando que el enrollamiento era habitual también en este periodo. En este trabajo se han revisado las estructuras coaptativas o de cierre situadas tanto en el cefalón como en el pigidio de los trilobites, así como las distintas articulaciones presentes en el tórax necesarias para el enrollamiento. También se describen y discuten los distintos tipos de enrollamiento especialmente en los trilobites del Cámbrico medio español. Se muestran por primera vez ejemplares de Agraulos longicephalus y Ctenocephalus antiquus en posición enrollada, Por último se discute la influencia de este comportamiento en la evolución de los trilobites.
Rheumatoid arthritis (RA) is an autoimmune disease that causes inflammation, pain, and ultimately, bone erosion of the joints. The causes of this disease are multifactorial, including genetic ...factors, such as the presence of the human leukocyte antigen (HLA)-DRB1*04 variant, alterations in the microbiota, or immune factors including increased cytotoxic T lymphocytes (CTLs), neutrophils, or elevated M1 macrophages which, taken together, produce high levels of pro-inflammatory cytokines. In this review, we focused on the function exerted by osteoclasts on osteoblasts and other osteoclasts by means of the release of exosomal microRNAs (miRNAs). Based on a thorough revision, we classified these molecules into three categories according to their function: osteoclast inhibitors (miR-23a, miR-29b, and miR-214), osteoblast inhibitors (miR-22-3p, miR-26a, miR-27a, miR-29a, miR-125b, and miR-146a), and osteoblast enhancers (miR-20a, miR-34a, miR-96, miR-106a, miR-142, miR-199a, miR-324, and miR-486b). Finally, we analyzed potential therapeutic targets of these exosomal miRNAs, such as the use of antagomiRs, blockmiRs, agomiRs and competitive endogenous RNAs (ceRNAs), which are already being tested in murine and ex vivo models of RA. These strategies might have an important role in reestablishing the regulation of osteoclast and osteoblast differentiation making progress in the development of personalized medicine.
The evolution process can be reconstructed by tracking the changes in the dynamic characters of life cycles. A number of related trilobites from the Cambrian of South China provide additional ...information for the study of trilobite evolutionary patterns, which has been hampered by previous incomplete fossil record though. Here,
and
represent related Cambrian oryctocephalid trilobites from South China, are comprehensively discussed over the ontogeny, and the results show that, from
via
to
, their exoskeletal morphology shows a directional evolution. Based on the direction of evolutionary changes in the development of
and
, we speculate that
likely evolved from
instead of
evolved from
, as was previously assumed. This inference is also supported by the phylogenetic tree. This research provides not only a better understanding of the mechanisms of evolution in trilobites, but also new insights for the relationship between developmental evolutionary changes and phylogeny in trilobites.
Taphonomic processes play an important role in the preservation of small morphological features such as granulation or pits. However, the assessment of these features may face the issue of the small ...size of the specimens and, sometimes, the destructiveness of these analyses, which makes impossible carrying them out in singular specimen, such as holotypes or lectotypes. This paper takes a new approach to analysing small-morphological features, by using an optical surface roughness (OSR) meter to create a high-resolution three-dimensional digital-elevation model (DEM). This non-destructive technique allows analysing quantitatively the DEM using geometric morphometric methods (GMM). We created a number of DEMs from three populations putatively belonging to the same species of trilobite (Oryctocephalus indicus) that present the same cranidial outline, but differ in the presence or absence of the second and third transglabellar furrows. Profile analysis of the DEMs demonstrate that all three populations show similar preservation variation in the glabellar furrows and lobes. The GMM shows that all populations exhibit the same range of variation. Differences in preservation are a consequence of different degrees of cementation and rates of dissolution. Fast cementation enhances the preservation of glabellar furrows and lobes, while fast dissolution hampers preservation of the same structures.
Eccaparadoxides? pradoanus and Eccaparadoxides mediterraneus are both widespread trilobite species described from the middle Cambrian of the Mediterranean region. Analysis based on a pooled sample of ...500 specimens demonstrates that many of the characters that have been used to define these species show continuous variations, some of which are related to ontogeny. In addition, morphometric analyses of metric characters show that the two species cannot be distinguished on the basis of these characters either. Many of the characters studied herein are widely used in definitions and descriptions of other paradoxidid species, which suggests that the taxonomic classification of other paradoxidids may be oversplit.
Two research teams have different opinions regarding the number of paradoxidine species close to the base of the Miaolingian in Morocco and Spain. Geyer & Vincent (2015) recognized five species based ...on a mosaic of overlapping characters that include some relative length and width ratios, qualitative descriptions of cranidial and pygidial outlines, and relief observations. In contrast, Álvaro et al. (2018) conducted a morphometric analysis of all these specimens from the Cambropallas telesto acme level of the Assemame quarry and concluded that the Moroccan material had been taxonomically over-split and was represented by only two species, Acadoparadoxides mureroensis and A. nobilis. Subsequently, Geyer et al. (2019) commented that we had not analysed some diagnostic characters, and applied the stratigraphic setting of their morphospecies as a diagnostic character for taxonomic identification. After sampling the Cambropallas telesto acme level in the Taroucht quarry, where the other team purchased its collection, and re-analysing the diagnostic characters claimed by Geyer et al. (2019), our conclusions are maintained: (i) morphometric values of several paratype specimens fall outside the purported ranges of diagnostic characters; (ii) all 2D morphometric analyses incorporating the diagnostic characters of the morphospecies are unable to detect interspecific differences, except for A. nobilis; and (iii) the slight concavity displayed by some pygidia, strongly controlled by preservation, is in need of 3D biometrical analysis. Hence, our proposed synonymy should be maintained until 3D statistical analyses are available on material preserved in carbonate or concretions.
Computational Fluid Dynamic simulations (CFD) show that the Ordovician trilobite Microparia speciosa had a high stability in the horizontal plane (parallel to the flow currents), suggesting that it ...could be very stable in the water column when it was enrolled, for hovering or to get stabilization when the current disturbed the swimming. This indicates a new way to use enrolment in trilobites during the Ordovician radiation, not only for protection against predators or the environment but also as a hydrodynamic tool to maintain stability within the water column. Metachronal propulsion was likely used by Microparia speciosa for swimming and, in a high-viscosity scenario, also for feeding. This is suggesting given that the vortex below Microparia speciosa takes particles directly to the mouth, and taken more particles when the trilobite is orientated in the way of the current (and no countercurrent). This suggests a passive feeding strategy for better energy saving when the trilobite is hovering in water column.
•Trilobites occupied the pelagic habitats during the Ordovician.•Metachronal system is a suitable mechanics for swimming in Microparia.•CFD suggests that enrolment could be used for hovering and/or stabilization.•Feeding currents could be used for feeding in the water column by Microparia.•Gradual adoption of nektonization in the the Palaeozoic seas.
The Solenopleurid trilobites comprise a very common family in East and West Gondwana. The type genus of this family, Solenopleura, has however suffered several taxonomic changes due to ...misunderstandings throughout the 20th century. In order to clarify and resolve all these problems, a revision is presented here that deals with both species involved in such misunderstandings, Calymene holometopa Angelin, 1851 and Calymene canaliculata Angelin, 1851. Both species are reassigned to the genus Solenopleura. The new descriptions and illustrations demonstrate that morphological features in Solenopleura holometopa are shared by other Scandinavian trilobites such as Solenopleura conifrons Westergård, 1952, which is closely related. Furthermore, the genus Gonzaloia Geyer, 1998 has been erected to include two species, G. canaliculata and G. conifrons. New descriptions herein suggest this genus is not supported by evidences and that included species should be provisionally considered, though with reservations, within the genus Solenopleura until a morphological and cladistic study of the whole genus will be able to provide significant evidence to separate both genera.
Les trilobites Solenopleurides forment une famille de trilobites fréquente dans le Gondwana Est et Ouest. Le genre-type de cette famille, Solenopleura, a cependant souffert d’incompréhensions qui ont mené à plusieurs changements taxonomiques au cours du 20e siècle. Afin de clarifier et de résoudre tous ces problèmes, la révision des deux espèces à leur origine, Calymene holometopa Angelin, 1851 et Calymene canaliculata Angelin, 1851, est présentée ici. Les deux espèces sont replacées dans le genre Solenopleura. Les nouvelles descriptions et illustrations démontrent que les caractères morphologiques de Solenopleura holometopa sont partagés par d’autres trilobites scandinaves comme Solenopleura conifrons Westergård, 1952, qui sont proches. De plus, Geyer (1998) a érigé le genre Gonzaloia pour inclure deux espèces, G. canaliculata et G. conifrons. Les nouvelles descriptions faites ici suggèrent que ce genre n’est pas soutenu par les évidences et que les espèces inclues devraient être provisoirement considérées, bien qu’avec réserve, au sein du genre Solenopleura jusqu’à ce qu’une étude morphologique et cladistique de l’ensemble du genre fournisse les preuves nécessaires à sa division.
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