State Of Chihuahua Research Articles

Ordovician stratigraphy and biota of Mexico

Abstract In Mexico, Ordovician sedimentary rocks are exposed in the states of Baja California, Sonora, Chihuahua and Oaxaca, comprising approximately 30 stratigraphic successions ranging from Lower to Upper Ordovician. The ages of the sequences have been established primarily by utilizing conodonts and graptolites, which have also allowed us to differentiate between platform and oceanic basin environments. The State of Sonora has the most complete Ordovician stratigraphic sequences, ranging from Tremadocian to Hirnantian. The deposits in Baja California are Floian in age, while the sequences of Chihuahua range from Sandbian to Katian, and the deposits in Oaxaca are Tremadocian. The Ordovician deposits of northern Mexico (Baja California, Sonora, and Chihuahua) present a palaeogeographic relationship to the North American craton, mainly owing to faunal interspecific affinities, while the southern deposits (Oaxaca) are controversial owing to the high degree of endemism of the faunas; however, they show affinity with Gondwana, Baltica and Avalonia, with a possible insular origin. The biotic assemblages of the Ordovician of Mexico include a variety of taxa, including algae, poriferans, corals, bryozoans, brachiopods, molluscs, trilobites, echinoderms, graptolites and conodonts as predominant elements. Despite many years of field studies in Mexican Ordovician localities, biostratigraphic correlations are as yet insufficient and incomplete or are based on limited interpretations. Thus, the Ordovician biostratigraphic data from Mexico compiled in the present paper have great potential and significant value. The advancement in the knowledge of the Ordovician biostratigraphy of Mexico will contribute to a major understanding of the relationships with the Ordovician System to a continental scale. Future advances will come mainly through increasing the amount and quality of data as well as improving biocorrelations among the Ordovician sequences of Mexico.

Actores sociales y gestión de la economía circular en el estado de Chihuahua, México

The article analyzes the participation of social actors in the management of the circular economy of urban solid waste in the state of Chihuahua, Mexico. The methodologyconsistedof semi-structured interviews, virtual interactive workshops(with the implementation ofelectronic surveys), surveysof municipalgovernments representatives,and personal communications. The resultsshow thatsocial actors barely glimpse the economic, social,and environmental meaning of betting on the circular economy. The article contributesto the analysis of the circular economy paradigm asa current sustainability tool.It is concludedthat little has been studied about the circular economy in Mexico and that the participation of non-state actors has not been valued and used efficiently. The articlereflects onwhat should and can be done with solid waste in Mexico in the future.

Dependence of bioavailability of lead compounds in soils on the type and source of contamination (the example of Mexico City and mining area of Parral, Mexico)

Evaluation and monitoring of soil contamination with heavy metals relies in most cases on their bulk concentrations whereas the risks of negative effects on human health depend upon the content of their bioavailable forms. The paper presents the study of the dependence of lead bioavailability in the surface soil horizons upon the contamination type and source. Two territories in Mexico with sharp difference of the source of pollution: Mexico City megapolis where the lead in soils originates from the ethyl gasoline burning and mining district in the south of Chihuahua State where the mine tailings are the source of the toxic elements including lead. Bulk lead concentrations were measured by the X-ray fluorescence method, bioavailability was estimated by the method imitating the effect of the stomach and intestine solutions. The research has shown that both in Mexico City (especially in its central part) and in the mining district in the Chihuahua State bulk lead concentrations are several times higher than the background values. The soils of the mining district have average bulk lead concentrations 787,5 mg/kg and show the average bioavailability values 64% whereas in the Mexico City megapolis average bulk concentrations of lead are lower - 324,7 mg/kg but bioavailability reaches 83% and in some samples even 100%. These results support the conclusion that despite lower bulk lead concentrations in Mexico City the risk of its negative effect on humans is higher than in the mining district polluted with the wastes of mining industry. The explanation of the observed tendency is that the chemical form of lead has a major influence on its bioavailability. Dependence of bioavailability upon the bulk concentrations within each study territory has not been established.

Identification of Traditional Music of Nonoava, Chihuahua

Throughout our history, war conflicts have served in some way as generators for the music of peoples. In the case of Mexico, the movements of troops and their bands in such an extensive territory, allowed their music to become known in other regions, even for its melodies to become popular. Specifically, two war movements in our country will be the subject of study for musical identity: Independence, and Revolution. This last social conflict unleashed a musical style that would soon become the favorite of the revolutionaries, specifically in the northern region. In Chihuahua in the 19th century, there were no musical expressions of identity. The emergence of wind music came to fill that gap, as it was adopted by Chihuahua´s society. Already in the 20th century, during Mexican Revolution is when a predilection for a certain type of music arises in Chihuahua. Perhaps nowhere else, throughout the country, were there so many military musical bands as in Chihuahua at this time, so their influence on the tastes of the population was representative. With this entire precedent, it will be possible to problematize how wind music was of vital importance in the social life of the people during the Mexican Revolution. Music bands will have a new valuation within society. Thanks to this, Chihuahua acquires a predilection for this type of wind music. In the town of Nonoava, Chihuahua, is where this musical aesthetics formed during the Mexican Revolution, somehow managed to subsist. It is known as the Nonoava style in which some musical elements similar to those of the Mexican Revolution still prevail on it today. This style is mainly made up of wind instruments. In their traditional repertoire, they continue to use European rhythms such as the polka, the redova, the chotis, and the waltz, among others. It is for this reason that the Nonoava style is the object of study in this work. This has turned the Nonoava style into an element of artistic export, since it has unique musical aesthetic elements, such as its instrumentation, repertoire and phrasing, which make it culturally valuable. In 2015, the city is named by the State Congress as “Nonoava, land of musicians”, becoming cultural heritage of the state of Chihuahua. However, the diffusion of Nonoava’s music has been scarce. More detailed research and work dissemination is necessary so that with this music is valued. It is for these reasons that it is pertinent to work. On the rescue and revaluation of this music, for the growth and dissemination of the Chihuahua´s culture. This work tries to find key pieces of this music.

Oregano oil extraction process using the "Coreganoil" coil steam drag method

It is an unprecedented process of extracting oil from the oregano plant (Lippia graveolens), from the distillation dry by the coil method. With innovation, a purer oil will be obtained by increasing the essences in thymol and carvacrol counteracting all possible moisture generated by the process. In addition to saving inputs for the extraction of volatile essences, which give it quality and purity, directly impacting the sale price. The objective that coreganoil offers to the market is the high purity of the oil extracted from the oregano plant, thanks to the new unprecedented dry distillation process using the coil method, resulting in an oregano oil with higher percentages of thymol and carvacrol, obtaining a purer oil. The methodological extraction procedure of this innovation is dry distillation by the coil method, which will allow the extraction process to be effective with a higher concentration of its physicochemical properties, giving it more added value. Coreganoil's contribution in obtaining it is a project that has the presence of a potential market in the south central region of the state of Chihuahua where there are 14,805 potential clients according to INEGI (2020). Potential clients for this project are mostly people of either sex dedicated to the pharmaceutical industry, culinary arts, farmers and fragrance industry and the general public.

Potential and economic feasibility of a wind power plant in Ciudad Juárez, México

This study investigated the wind energy potential of Ciudad Juárez (Chihuahua, México) for a whole year. The viability of employing three small-scale wind turbine models, including the S-343, Bergey BWC Excel, and AOC 15/50, in Ciudad Juarez, located in the northern Mexican state of Chihuahua in Mexico, is studied in the first stage using RETScreen software. The performance of these three turbine models was subjected to sensitivity analysis in the following study stage using the three defined economic scenarios, assuming a 7% inflation rate, a 9% discount rate, a 7% fuel cost escalation rate, and a 20-year project duration. Finally, the circumstances under which these turbines operate in Ciudad Juarez are discussed economically. Findings indicate that the study site is not economically appropriate, not even for the installation of specific small wind turbines. Finally, it was suggested that the viability of adopting alternative renewable energy systems, such as solar and hybrid systems (photovoltaic wind), be examined in the upcoming study in Ciudad Juárez.

Potential Distribution of Cedrela odorata L. in Mexico according to Its Optimal Thermal Range for Seed Germination under Different Climate Change Scenarios.

Cedrela odorata is a native tree of economic importance, as its wood is highly demanded in the international market. In this work, the current and future distributions of C. odorata in Mexico under climate change scenarios were analyzed according to their optimal temperature ranges for seed germination. For the present distribution, 256 localities of the species' presence were obtained from the Global Biodiversity Information Facility (GBIF) database and modelled with MaxEnt. For the potential distribution, the National Center for Atmospheric Research model (CCSM4) was used under conservative and drastic scenarios (RCP2.6 and RCP8.5 Watts/m2, respectively) for the intermediate future (2050) and far future (2070). Potential distribution models were built from occurrence data within the optimum germination temperature range of the species. The potential distribution expanded by 5 and 7.8% in the intermediate and far future, respectively, compared with the current distribution. With the increase in temperature, adequate environmental conditions for the species distribution should be met in the central Mexican state of Guanajuato. The states of Chihuahua, Mexico, Morelos, Guerrero, and Durango presented a negative trend in potential distribution. Additionally, in the far future, the state of Chihuahua it is likely to not have adequate conditions for the presence of the species. For the prediction of the models, the precipitation variable during the driest month presented the greatest contribution. When the humidity is not limiting, the thermal climatic variables are the most important ones. Models based on its thermal niche for seed germination allowed for the identification of areas where temperature will positively affect seed germination, which will help maximize the establishment of plant populations and adaptation to different climate change scenarios.

Simulation of variations in the speed of fire propagation, during a prescribed burn

Fire behavior simulations are generally based on standardized models of forest fuels, which can hardly represent allpossible variations in forest ecosystems, which can result in biased estimates of fire behavior. Due to this, in the presentwork a comparative analysis of simulations of fire behavior (propagation rate [m/min]) is made, during the course of aprescribed burning in favor of the slope, in a pine-oak forest stand from the state of Chihuahua. These simulations varied inrelation to: a) fuel models; b) fuel loads; and c) wind speed. The models tested were: 1) the one that resulted from amultiple regression (considering temperature, relative humidity and slope); 2) the fuel model M-8 and its variant M-8R(includes the values of fuel charges obtained in the field); and 3) the fuel model M-9 and its variant M-9R (includes thevalues of fuel charges obtained in the field). The equations of the trends defined by the correlation between the relativehumidity (%) and the speed of fire propagation (m/min) were generated. Although neither model was found to bestatistically significant, the best fit was defined with the regression equation:, which can be used in apractical way for a rough estimation of the rate of fire spread (RP). It is concluded that, in general, the selected modelswere not appropriate for simulating fire behavior during prescribed burning. This highlights the need to generate specificfuel models for the analyzed vegetation and its variations in density, structure and composition

A Brazilian Free-tailed Bat, Tadarida brasiliensis (I. Geoffroy, 1824) (Chiroptera, Molossidae), colony in Santa Eulalia, Chihuahua, Mexico, with records of other bat species

We report here the first record of a colony of the Brazilian Free-tailed Bat, Tadarida brasiliensis (I. Geoffroy, 1824), in a mine located in central Chihuahua, Mexico. This record represents the most central point of the distribution of the species in the state and is located in the Central Valleys biome. We highlight the importance of recognizing and preserving this mine as a refuge for the largest bat colony reported in the state of Chihuahua.

Sustainable Industrial Sotol Production in Mexico—A Life Cycle Assessment

Sotol is a distilled spirit made in the north of Mexico produced from the wild plant Dasylirion wheeleri. Although sotol was awarded the Designation of Origin (DO) in 2002 and has an economic influence on the DO region, its environmental profile has not been determined. For that reason, this paper reports a Life Cycle Analysis (LCA) of the industrial sotol production process in the Mexican state of Chihuahua to determine any significant environmental impacts caused by sotol production from raw material acquisition to the packaging stage. The LCA was modeled using SimaPro 8.5.2 software (PRé Sustainability, Amersfoort, The Netherlands) and the environmental impacts were calculated using the CML-IA baseline v3.03/EU25 impact assessment technique. The findings reveal that sotol beverage manufacturing considerably affects three of the eleven impact categories selected and that the harvesting and bottling stages have the greatest negative environmental impact of all the sotol production stages. According to empirical data, one bottle (750 mL) of sotol results in a higher carbon dioxide value than any other spirit evaluated in earlier LCA studies, with white, rested, and aged sotol generating 5.07, 5.12, and 5.13 kg CO2 eq, respectively. Other drinks, such as mescal, classic gin, and whisky generate only 1.7, 0.91, and 2.25 kg CO2 eq, respectively. In conclusion, sotol distillery companies should start to decrease road transport of raw materials used in the packaging stage and begin to cultivate sotol instead of extracting it from the wild as strategies to achieve cleaner production.

Estimating biomass in grasslands through traditional methods and the use of drones in the State of Chihuahua, Mexico

Objective: To evaluate three biomass estimation methods (Unmanned Aerial Vehicle (UAV or drone), ceptometer, and canopy height), comparing them to the quadrant method in an arborescent tufted grassland in the state of Chihuahua.Methodology: The study was conducted in Teseachi, Namiquipa, in october 2020. We located thirty random points. The first biomass estimation method used was UAV. Once the drone flights were completed, the quadrant was placed and the coordinates were determined. We carried out nine readings using a ceptometer and obtained an average. Subsequently, we measured the average canopy height. Finally, all forage within the quadrant was cut at ground level and packed for laboratory analysis. The Agisoft Metashape software was used to process the SfM of the aerial images, using nine sampling points, applying the NGBDI vegetation index, and calculating the averagepixels of a 3 x 3 m moving window. A simple linear regression model was used to analyze the data with the R Project software, version 4.0.3.Results: The simple linear regression model showed an R 2 of 0.62 (p<0.01), 0.55 (p<;0.001), and 0.48 (p<0.001), for UAV, ceptometer, and canopy height, respectively.Study Limitations: There were no limitations for this report. Conclusions: Data obtained with UAVs can generate predictive biomass maps with acceptable accuracy levels. The ceptometer leaf area index is a reliable method to estimate forage yield. However, using the canopy height method is not advisable to estimate forage yield, since its correlation is weak.

Characterization of the morphometry, germination process, phytochemicals, and antioxidant capacity of seeds of three species of the genus Cylindropuntia (Cactacea) of Chihuahua state

Cylindropuntia is a genus of cylindrical cacti found in northern Mexico. This study aimed to describe the fruit and seed morphometry, characterize the germination process, as well as determine the seed phytochemicals in three species of the genus Cylindropuntia from the state of Chihuahua in México: C. imbricata, C. spinosior, and C. leptocaulis. To measure the morphometric parameters, 20 fruits and 20 seeds from each fruit were used for each specie. For the characterization of the germination process, two scarification treatments were applied, and the germination was allowed for 42 days. Different parameters of the germination process were calculated as the germination percentage, mean germination time, germination speed, and mean germination speed. The concentration of reducing sugars, total phenols, tannins, flavonoids, antioxidant activity (DPPH and FRAP), and protein content were determined from seeds under basal conditions. Results revealed significant differences (p ? 0.05) for morphometric parameters in the fruit and seed of the three species examined, showing C. imbricata the highest values in both tissues, followed by those obtained for C. spinosior and C. leptocaulis, respectively. The germination percentage was higher in C. leptocaulis (13.3%), although achieved in a longer mean germination time (27.7 days), facing C. spinosior that presented the lowest values for the germination percentage (3.3%), mean germination time (4.6 days), and germination speed index (0.024 days). Seeds from C. leptocaulis showed the highest values for reducing sugar content (31.82 mg glucose·g?1 of dry weight) and the antioxidant activity determined by DPPH (26.37 mg CE·g?1of dry weight), whereas C. spinosior seeds showed the highest ones for the total phenols content (3.08 mg GAE·g?1 of dry weight) and the antioxidant activity determined by FRAP (11.7 mmol TE·g?1 dry weight). Besides, C. imbricata showed the highest value in the protein content (5.6 mg protein·g?1). This study provides the first data on seed phytochemicals and information on the germination process of these three species of Cylindropuntia, showing differences among them in the diverse parameters measured.

Dynamics of Major and Trace Elements in Water-Soil-Tree Interaction: Translocation in Pyrus malus in Chihuahua, Mexico Using ICP-OES and Its Health Risk Implications.

The transference of metals from water irrigation and soil to plants is a possible pathway of contamination for the trophic chain. This research is focused on the distribution of 16 analytes in the water–soil–tree (Pyrus malus) interaction in an agricultural region in the state of Chihuahua in Mexico from August 2019 (first sampling) to August 2020 (second sampling). The apple variety under investigation was Golden Delicious; it was found that the trace elements of As (0.18–0.34 mg·kg−1) and Cd (0.11–0.14 mg·kg−1) in the apple were above the corresponding permissible limit, according to FAO/WHO, and Cr (0.08–0.86 mg·kg−1) was below the limit. Furthermore, the health risk implications were estimated by the Hazard Quotients (HQ) and carcinogenic risk (CR). For carcinogenic risk, As, Cd, and Cr exceeded the risk limit (CR > 10−4). This investigation as well provides a link for similar research around the globe. Major and trace elements detection was performed with the Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) technique, along with a prior homogenization of samples and microwave acid digestion. To obtain the statistical behavior, an analysis of variance and correlation was performed.

La deserción escolar por problemas de acceso y disponibilidad de conectividad a internet en los estudiantes de la UAIM, unidad Mochicahui, El Fuerte, Sinaloa

The present research has the objective of identifying the rate and causes of school dropout originated by the difficulty of access and availability of internet connectivity of incoming students at the Universidad Autónoma Indígena de México Mochicahui unit. For this purpose, a medication instrument based on a six-point Likert scale was used, using the descriptive method with a mixed approach. The results show that more than 63% of the students come from Sinaloa and the rest from the states of Chiapas, Chihuahua, Sonora, Baja California and State of Mexico, of which almost 80% speak some indigenous language, likewise almost 68% express that the use of cell phones is their main communication resource to develop their academic activities, among the main difficulties for which they cannot establish a good internet connection, is because of the geographical location where they live.

Variabilidad de la precipitación (1660-2018) para el oeste de Chihuahua inferida con anillos de árboles

Introduction: Tree rings play a significant role for the reconstruction of climate variables on century scales. Objective: To reconstruct the variability of precipitation for the western part of the state of Chihuahua, based on tree rings of Pseudotsuga menziesii (Mirb.) Franco, Pinus arizonica Engelm.and Pinus strobiformis Engelm. Materials and methods: Samples were extracted with a Pressler drill, dated and growth indexes were generated based on dendrochronological techniques. A correlation analysis was run between regional chronology and observed precipitation data. A regression model was used to reconstruct precipitation. A spectral analysis determined the recurrence of droughts and the influence of El Niño Southern Oscillation (ENSO) on precipitation variability. Results and discussion: The relationship between the chronologies was statistically significant and a regional series of 359 years was developed. October-June precipitation had the highest impact on growth (r = 0.73, P < 0.01), so the variability of precipitation for that period was reconstructed for the last 359 years. Severe droughts were detected in the periods 1751-1768, 1807-1810 and 1945-1956 and a recurrence of droughts every 50 years was identified. The reconstructed precipitation variability is significantly modulated by ENSO at different time scales and frequencies. Conclusion: Paleoclimatic series help us to spread the knowledge of climate in specific geographic regions and to analyze the recurrence of extreme events (droughts).

Sitotroga cerealella-resistant mexican maize races (Zea mays L.), new sources of resistance for commercial maize breeding

Sitotroga cerealella (Oliv.) (Lepidoptera: Gelechiidae) is one of the most important post-harvest pests of maize Zea mays L. Some Mexican maize races (Z. mays) could be a novel source of resistance against S. cerealella to improve commercial maize varieties, lines and hybrids. We studied the resistance of Mexican maize races, recollected at Chihuahua State to S. cerealella. We focused on antibiosis and tolerance of maize to S. cerealella. Cristalino-079 maize race shows low level of consumption in grams and percentage, increased larvae mortality before to entering the seed. In addition, Cristalino-079 reduced first adult’s generation and show the largest biological cycle. Due to the small number of emerged adults, there was very little grain weight loss in resistant maize race. The compound that causes high mortality of larvae before to entering the grain is in the pericarp of resistant maize races. The compound that causes longest development time is in the endosperm and embryo. Cristalino-079 show the better level of resistance to S. cerealella infestation in almost all traits studied and this can be used as source of resistance for maize breeding.

Biodegradation of polycyclic aromatic hydrocarbons by Acremonium sp. activity

Chihuahua State is the largest apple producer in Mexico. To prevent apples from freezing during the winter, petroleum-based fuels are used to heat the orchards. In this research work, a microorganism isolated from inside of a fuel plastic container was identified through morphological analysis as the fungus Acremonium sp. By cultivating the fungus in potato dextrose agar medium (PDA), we were able to study the biodegradation rates of three polycyclic aromatic hydrocarbons (PAHs). The isolated microorganism was incubated at 28 ºC in M9 mineral liquid medium using phenanthrene, anthracene, and pyrene as the only carbon source at a concentration of 50 µg/mL. Degradation of PAHs was monitored using an environmentally friendly reverse phase ultra-high-performance liquid chromatography (UHPLC) system, with a C18 column, 30% water acidified at 0.1% with trifluoroacetic acid, and 70% acetonitrile as the mobile phase, 40 ºC column temperature, and UV detection at 254 nm. After 30 days of biodegradation (optimal time), the final mean concentration for individual degradation experiments were 2.51 µg/mL phenanthrene, 3.02 µg/mL anthracene and 5.53 µg/mL pyrene. Those final concentrations indicate degradation percentile of 95%, 94%, and 89%, respectively. Biodegradation experiments combining all three PAHs showed similarly high degradation percentiles of 93%, 94%, and 85% for phenanthrene, anthracene, and pyrene, respectively. The dry weight average at day 30 in the individual and combined degradation experiments was 2.34 mg/mg PAHs degraded.

Gamma radiation on seeds of natal grass [Melinis repens (Willd.) Zizka] induced plant's morphological and nutritional variability.

Induced mutagenesis through gamma radiation generates structural and chemical changes in plants. This study evaluated the morphological and nutritional variability of natal grass [Melinis repens (Willd.) Zizka] plants produced from seed irradiated with gamma radiation. Natal grass seed was collected from wild populations in the state of Chihuahua, Mexico. The seed was exposed to a source of Co60. The radiation doses were: 0, 10, 50, 100, 150, 200, 250, 300 and 350 Gray (Gy). Sixty-six first generation mutant genotypes (M1), produced from irradiated seed, and nine non-mutant genotypes (M0), developed from non-irradiated seed (0 Gy), were evaluated. For the morphological characterization, 18 variables were measured on the plants when they were at the reproductive stage. The nutritional analysis was performed on the M0, as well as on a group of plants from the M1, which resulted morphologically different (p <0.005) from the rest. The differenced M1 plants were classified as promising mutant genotypes (M1p). Results showed that variability was induced in the M1p. These individuals presented morphological differences in leaf weight-tillering weight ratio and foliage height, compared to the rest of the plants (p <0.001). The M1p 250–10 genotype presented the highest (p <0.001) crude protein and the lowest (p <0.001) lignin contents. Gamma radiation in the seed of natal grass induced morphological and nutritional variability. With that, promising mutant genotypes, with desirable morphological and nutritional attributes, were identified.

Identification of changes in the rainfall regime in Chihuahua's state (México)

The impacts of Climate Change are not homogeneous globally or for a country or region as a whole. Consequently, it is essential to carry out studies to identify its effects in particular areas. Due to its geographical and topographic characteristics, Chihuahua's state is vulnerable to the adverse effects of Climate Change. The scarce availability of water resources leads to problems of social pressure and economic impact. This paper analyzes the alteration of the rainfall regime in Chihuahua's state and its association with Climate Change. For this, historical characterization is used; trend analysis using the Mann Kendall test; and calculation of 10 indices of climatic extremes proposed by the Group of Experts for Detection and Climate Change Indices for the precipitation variable. The results showed that the precipitation patterns in the south and southeast of Chihuahua's state have been gradually modifying, with a downward trend in annual accumulated and reduction of wet days. Still, in counterpart, there is a slight intensification of extreme rainfall. This fact added to the growing demand for water resources in the entity, requests for public policies for sustainable management and responsible use by users. Otherwise, there is a risk of experiencing negative effects associated with the over-exploitation of water, not only for the resource users but also for the environment.

Fast spread followed by anagenetic evolution in Eurasian and North American Amphimachairodus

ABSTRACT The charismatic sabretooth cat Amphimachairodus has numerous but largely fragmentary records across late Miocene deposits of Africa, Eurasia and North America. The genus has a complex taxonomic history, and the majority of Amphimachairodus materials come from isolated localities, often studied without stratigraphic context. Here, we analyse the long, continuous records from the classic Chinese Baode strata, which produce Amphimachairodus throughout the section, and demonstrate that an A. palanderi-horribilis chronospecies succession represents a continuum of in situ anagenetic evolution of increasing size. We then synthesise chronological occurrences of Amphimachairodus from all Holarctic records and reframe their evolution as a case of chronospecies succession. Two parallel anagenetic lineages are evident: a Eurasian A. giganteus-palanderi-horribilis chronospecies succession and second, a North American A. coloradensis-alvarezi chronospecies succession following an immigration event in the early Hemphillian. In addition to greater hypercarnivory evidenced by dental specialisation, the Eurasian lineage shows a trend towards a large body size, whereas the North American lineage decreases in size. We take this opportunity to describe materials of Amphimachairodus alvarezi from Yepómera (latest Hemphillian) in the state of Chihuahua, Mexico, and previously undescribed materials from San Miguel de Allende Basin. We review taxonomic status of Chinese A. horribilis and related taxa.