Magnitude 6.5 Earthquake in Guerrero State, Mexico.

The United States Geological Survey recorded a Magnitude 6.5 Earthquake at a depth of 35.0 km, approximately 4 km to the north of the resort of Rancho Viejo in Guerrero State, slightly before 10.00 am local time (slightly before 2.00 pm GMT) on Friday 2 January 2025. This even was felt across much of southern and central Mexico, with at least two people having died, a 50-year-old woman in Guerrero State, and a 60-year-old man in Mexico City. At least 12 further people were injured by the event. 

The approximate location of the 3 January 2026 Guerrero State Earthquake. Contour lines show rates of movement during the quake, the red line is the Middle American Trench. USGS.

Mexico is located on the southernmost part of the North American Plate. To the south, along the Middle American Trench, which lies off the southern coast off Mexico, the Cocos Plate is being subducted under the North American Plate, passing under southern Mexico as it sinks into the Earth. Guatemala is located on the southern part of the Caribbean Plate, close to its boundary with the Cocos Plate, which underlies part of the east Pacific. The Cocos Plate is being pushed northwards by expansion of the crust along the East Pacific Rise, and is subducted beneath the Caribbean Plate along the Middle American Trench. This is not a smooth process, and the plates frequently stick together then break apart as the pressure builds up, causing Earthquakes in the process. 

The position of the Cocos, Nazca and Rivera Plates. MCEER/University at Buffalo.

The Cocos Plate is thought to have formed about 23 million years ago, when the Farallon Plate, an ancient tectonic plate underlying the East Pacific, split in two, forming the Cocos Plate to the north and the Nazca Plate to the south. Then, roughly 10 million years ago, the northwesternmost part of the Cocos Plate split of to form the Rivera Plate, south of Beja California.

In a paper published in the Journal of Geophysical Research, in 2012, a team led by Igor Stubailo of the Department of Earth and Space Sciences at the University of California Los Angeles, published a model of the subduction zone beneath Mexico using data from seismic monitoring stations belonging to the Mesoamerican Seismic Experiment, the Network of Autonomously Recording Seismographs, the USArray, Mapping the Rivera Subduction Zone, and the Mexican Servicio Sismologico Nacional.

The seismic monitoring stations were able to monitor not just Earthquakes in Mexico, but also Earthquakes in other parts of the world, monitoring the rate at which compression waves from these quakes moved through the rocks beneath Mexico, and how the structure of the rocks altered the movement of these waves.

Based upon the results from these monitoring stations, Stubailo et al. came to the conclusion that the Cocos Plate was split into two beneath Mexico, and that the two plates are subducting at different angles, one steep and one shallow. Since the rate at which a plate melts reflects its depth within the Earth, the steeper angled plate melts much closer to the subduction zone than the shallower angled plate, splitting the Trans-Mexican Volcanic Belt into sections above the different segments of the Cocos Plate, and causing it to apparently curve away from the subduction zone.

Top the model of the Cocos Plate beneath Mexico, split into two sections (A & B) subducting at differing angles. (C) Represents the Rivera Plate, subducting at a steeper angle than either section of the Cocos Plate. The Split between the two has been named the Orozco Fracture Zone (OFZ) which is shown extended across the Cocos Plate; in theory this might in future split the Cocos Plate into two segments (though not on any human timescale). Bottom Left, the position of the segments on a map of Mexico. Darker area is the Trans-Mexican Volcanic Belt, orange circles are volcanoes, brown triangles are seismic monitoring stations, yellow stars are major cities. Bottom Right, an alternative model showing the subducting plate twisted but not split. This did not fit the data. Stubailo et al. (2012).

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At least 28 people have died in flooding and landslides associated with Tropical Storm Raymond in Mexico.

At least 28 people have died in Mexico on Thursday 9 and Friday 10 October 2025, as Tropical Storm Raymond has moved up the east coast of the country. Thirty one of the country's thirty two states have been affected by storm-related incidents, although the State of Hidalgo, to the north of Mexico City, has been the worst hit, with several rivers bursting their banks due to high rainfall, leading to 16 known deaths, and more than a thousand homes, as well as 59 medical centres and 308 schools, being impacted by flooding. A further nine deaths have been reported in the neighbouring State of Puebla, which lies to the south and east of Mexico city, with another thirteen people missing, and a gas pipeline fractured by a landslide. In the State of Veracruz, on the coast to the east of Hidalgo and Pueblo, at least two people have died, including a police officer and  child caught in a landslide.

Flooding in Veracruz State, Mexico, this week. Marco Antonio Perez/AFP.

Tropical storms are caused by the warming effect of the Sun over tropical seas. As the air warms it expands, causing a drop in air pressure, and rises, causing air from outside the area to rush in to replace it. If this happens over a sufficiently wide area, then the inrushing winds will be affected by centrifugal forces caused by the Earth's rotation (the Coriolis effect). This means that winds will be deflected clockwise in the northern hemisphere and anti-clockwise in the southern hemisphere, eventually creating a large, rotating Tropical Storm. 

The structure of a tropical cyclone. Wikimedia Commons.

Despite the obvious danger of winds of this speed, which can physically blow people, and other large objects, away as well as damaging buildings and uprooting trees, the real danger from these storms comes from the flooding they bring. Each drop millibar drop in air-pressure leads to an approximate 1 cm rise in sea level, with big tropical storms capable of causing a storm surge of several meters. This is always accompanied by heavy rainfall, since warm air over the ocean leads to evaporation of sea water, which is then carried with the storm. These combined often lead to catastrophic flooding in areas hit by tropical storms. 

The formation and impact of a storm surge. eSchoolToday.

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Cochimicetus convexus: A new species of Eomysticetid Whale from the Late Oligocene of Baja California Sur, Mexico.

Baleen Whales, Mysticetes, are the largest Animals alive today, and, as far as we can tell, the largest Animals ever to have lived. They are able to achieve this huge size by a unique feeding mechanism; using a system of keratinaceous baleen plates  to filter food items (such as Crustaceans of small Fish) from the water. The largest Baleen Whales are lunge feeders, capable of engulfing whole shoals of prey-items, then  trapping them on the baleen plates as the accompanying water is pushed out through. The earliest Mysticetes appeared in the Late Eocene, though these were still Toothed Whales, little different from the ancestors of today's Odontocetes. The first true Baleen Whales were the Eomysticetids, a group which appeared in the Early Oligocene. Eomysticetids had baleen plates similar to those of modern Baleen Whales, but appear to have lacked the ability to lunge-feed in the same way, and were not capable of reaching the same sizes.

In a paper published in the journal Palaeontologica  Electronica in January 2025, Cielo Cedillo-Avila and Gerardo González-Barba of the Museo de Historia Natural at the Universidad Autónoma de Baja California Sur,  and Azucena Solis-Añorve, also of the  Museo de Historia Natural, and of Posgrado of Ciencias Marinas and Costeras at the Universidad Autónoma de Baja California Sur, describe a new species of Eomysticetid Whale from the Late Oligocene San Gregorio Formation of Baja California Sur.

The new species is described from a single specimen comprisng a partially complete skull with a length of 147 cm, along with both mandibles and tympanic bulla. It is named Cochimicetus convexus, where 'Cochimicetus' refers to the indigenous Cochimi people, a nomadic group who once inhabited the northern part of Baja California Sur, and 'convexus' refers to the convex shape of the anterior tip of the tympanic bulla, which tends to be pointed in other Eomysticetid Whales.

Dorsal view of the holotype of Cochimicetus convexus. (A) Image showing the identified structures. (B) photography with scale 10 cm. Cedillo-Avila et al. (2025).

Cochimicetus convexus is the fourth species of Eomysticetid Whale from the Oligocene of Baja California Sur, demonstrating the importance of the area for our understanding of the early evolution of the Mysticetes. 

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Tubular fossils from the Terminal Ediacaran La Ciénega Formation of Sonora State, Mexico.

The first fossils of organisms with mineralized skeletons appear in strata from the Terminal Ediacaran, between about 550 and 538 million years ago. This appearance coincides with the decline of the organisms of the 'classical' Ediacaran White Sea Fauna. One of the most abundant of these early mineralized fossils is Cloudina, a diverse group of fossils with a cone-in-cone or funnel-in-funnel structure, although the extent to which Cloudina was mineralized appears to have been variable, with some forms heavily mineralized, some only lightly so, and others apparently having skeletons made from tough organic materials. Cloudina was first described from the Terminal Ediacaran Nama Formation of Namibia, but has since been found in Brazil, Spain, China, Oman, and the United States, and is considered to be a useful index-fossil for the Terminal Ediacaran. 

While Clodina is often the dominant fossil in Terminal Ediacaran assemblages, it is often found alongside a variety of other tubular fossils, such as Namacalathus, Namapoikia, and Sinotubulites. Sinotubulites fossils have a tube-in-tube structure and often have annular or longitudinal ridges, as well as both circular and polygonal cross-sections. Originally described from South China, Sinotubulites has also been described from Mexico, the United States, Brazil, Spain, and Namibia. Interestingly, which specimens of Cloudina have been discovered in many places with what-appear to be drill-holes, possibly the oldest known example of predation by boring, this has not been observed in specimens of Sinotubulites, even when the two are found together, potentially representing the oldest example of prey-selection.

Ediacaran fossils in the Terminal Ediacaran La Ciénega Formation of Sonora State, Mexico, were first described in the mid 1980s. The initial descriptions suggested a variety of tubular fossils were present, including Sinotubulites but not Cloudina. However, subsequent studies of the material led to the conclusion that these 'Sinotubulites' fossils were in fact specimens of Cloudina which had undergone taphonomic alteration, causing them to develop compactional folds which were mis-interpreted as the longitudinal striae of Sinotubulites.

In a paper published in the Journal of Paleontology on 10 October 2024, James Schiffbauer of the Department of Geological Sciences and X-ray Microanalysis Laboratory at University of Missouri, Clara Wong also of the Department of Geological Sciences at University of Missouri, and of the Department of Geosciences at Smith College, Cassidy Davis, also of the Department of Geological Sciences at University of Missouri, Tara Selly, again of the Department of Geological Sciences and X-ray Microanalysis Laboratory at University of Missouri, Lyle Nelson of the Department of Earth Sciences at Carleton University, and Sara Pruss, also of the Department of Geosciences at Smith College, re-examine the La Ciénega Formation fossil assemblage, using modern methodologies to provide new insights into the community structure preserved there.

The Caborca Block in Sonora comprises a series of Late Neoproterozoic and Early Palaeozoic strata laid down in shallow-marine environments on the edge of first a rift zone and then the southern margin of the continent of Laurentia. Here the early Ediacaran Period is represented by the Clemente Formation, which is followed by the Late Ediacaran La Ciénega Formation, and the Cambrian Cerro Rajón Formation. Uranium/lead analysis of zircons from the uppermost layer of the La Ciénega Formation places the age of this at 539.4 million years, the latest part of the Ediacaran. Zircon is a volcanic mineral that forms as liquid magma slowly cools to form solid rock. As zircon forms it can incorporate a variety of different elements into its crystal matrix, including uranium but not lead. This is useful as over time uranium decays to form lead, so any lead in a zircon mineral must be the result of the decay of uranium. Since the decay of uranium to lead occurs at a steady rate, it is possible to determine the age of zircons by measuring the ratio of uranium to lead within them.

Locality map and stratigraphy of the Cerro Clemente section: (1) Map indicating position of Caborca localities (yellow star) in northern Mexico, and plausibly correlative fossiliferous units (grey stars) in the southwestern USA. (2) Satellite image from Google Earth denoting the topography of the Cerro Clemente section with longitude and latitude markers. (3) Geologic map corresponding to the same map view in (2). (4) Photograph of collected coquina block. (5) Stratigraphic section with carbon isotope chemostratigraphy showing position of uranium-lead radiometric date (green star) and sampled fossil horizon (yellow star). Schiffbauer et al. (2024).

Schiffbauer et al. obtained a block from a silicified coquina bed within the La Ciénega Formation at the Cerro Clemente section measuring 15 cm x 10 cm x 10 cm. This was partitioned into a number of fragments, which were then treated to different analysis regimes, including dissolution with acetic acid to allow the collection of fossil residues, scanning electron microscope analysis, elemental analysis using an energy dispersive X-ray spectrometer, and thin sectioning for visual microscopy.

These methods enabled them to identify five distinct forms of tubes. Firstly, there were tube-in-tube structures with annular ridges and possible laminae, interpreted as Sinotubulites. Secondly, there were tubes made up of a series of tightly-fitting funnel-in-funnel structures lacking rims, interpreted as Cloudina. Thirdly, there were funnel-in-funnel structures with thickened and/or pronounced rims, interpreted as the Cloudinomorph Saarina. Fourthly, simple straight tubes, and fifthly, simple curved tubes.

Morphological groupings of fossils (SEM). (1, 2) Form 1, Sinotubulitids in lateral (1) and cross sectional (2) views: (1) lateral view showing diagnostic transverse corrugations; (2) cross section illustrating multiple tube-in-tube construction, with substantial silica overgrowth. (3), (4) Forms 2 and 3, Cloudinomorphs, Cloudina sp. indet. (3) and cf. Saarina sp. indet. (4): (3) Cloudina with two nested funnel units and no thickened apertural rims; (4) the other Cloudinomorph form showing thickened apertural rims with observable drooping imbrication. Also note slight change in growth direction or plastic deformation at tube midpoint, along with slight tubular compression. (5), (6) Forms 4 and 5, smooth tubes that are either straight (5) or sinuous (6). Scale bars are 1 mm (1), (3), (4), and (6), 500 μm (2), and (5).  Schiffbauer et al. (2024).

Of the identifiable individual specimens, 33 were tube-in-tube structures, 20 were non-rimmed funnel-in-funnel structures, 23 were rimmed funnel-in-funnel structures, five were straight smooth tubes, and ten were curved or sinuous tubes. Thus, Cloudinomorphs were the most abundant group, making up about 40% of the sample, with Sinotubulitids comprising about 31% of the sample, and unidentified tubes making up 28%.

The Cloudinomorphs ranged from 0.88 to 2.61 mm in diameter, with an average of 1.51. The rimless forms were on average slightly larger, ranging from 1.13 to 2.61 mm in diameter, with an average of 1.65 mm., while the rimmed forms ranged from 0.88 to 2.26 mm in diameter, with an average of 1.43 mm. The Sinotubulitids were generally larger than the Cloudinomorphs, ranging from 1.11 to 5.23 mm in diameter, with an average diameter of 2.41 mm. The indeterminate tubular fossils ranged from 0.36 to 1.84 mm in diameter, with an average of 1.21, and little difference between the two forms (the straight forms average 1.22 mm in diameter, the sinuous forms 1.17 mm). The length of the fossils was much harder to estimate, as fossils of this size are prone to fragmentation; the longest Cloudinomorph found was 4.49 mm long, the longest Sinotubulitid 5.82 mm, and the longest smooth tube 5.59 mm. 

Seen in thin section, much of the block was made up of densely packed tubular fossils. The majority of these were calcareous in nature, with only a minority of examples being silicified. However, the acid-extraction method produced only silicified specimens, with the calcarious fossils apparently lost from the portion of rock treated this way. This is likely to have given a distorted view of the nature of the total assemblage. Furthermore, the silicified fossils within the block cut into thin sections often had very fine skeletal walls, sometimes as little as 2–3 μm thick, while all of those extracted by acid etching were much courser, with the thinnest being 0.15–0.32 mm thick, suggesting that finer silicious fossils had also been lost. 

Petrographic thin section photomicrographs. (1) Silicified tube examples (brighter white material) in transverse section (left) and longitudinal section (right). (2) Silicified funnel-in-funnel tube in longitudinal section, non-orthogonal to the length of the tube. Note blocky calcareous infilling and potential fine layering in the tube wall. (3) Transverse plane of non-silicified tube, with apparent fine layering and blocky calcareous infill. (4) Longitudinal plane of non-silicified tubular fossil with fine layering and micritic infill. Scale bars are 1 mm. Schiffbauer et al. (2024).

The calcitic tubes visible in the thin sections appeared to be made from a fine micrite, with courser carbonate and even dolomite crystals separating them. This could also be seen in scanning electron microscopy images, where it could also be seen that while the fine structures of the fossils were preserved, they were altered by the development of courser crystals around them, with many Cloudinomorph fossils having an elliptical cross-section (interpreted as distortion of an original circular shape), whole Sinotubulitids showed flattening, irregular cross-sections, and corrugation. One smooth-walled tube appears to have been helically twisted along its length. This makes it unlikely that the original surface structure of any of the fossils was preserved.

Surface and deformative features of silicified fossils (scanning electron microscope images). (1) Sagittally flattened Sinotubulitid specimen. (2) Imbricated funnel rims (dashed white lines to guide orientation) of cf. Saarina specimen with little-to-no flattening. (3) Torted funnel (left dashed curve), broken funnel wall (arrow), and intact funnel aperture (right dashed curve) of Cloudina sp. indet. specimen. (4) Ovoid puncture (arrow) in smooth (curved) tube. (5) Subcircular puncture (arrow) in Cloudina sp. indet. funnel (infilled). Scale bars are 1 mm. Schiffbauer et al. (2024).

Backscattered electron imaging and energy-dispersive X-ray spectroscope mapping of the thin sections suggested that there were many 'ghost tubes' present, which could not be visually observed, which were very nearly identical in composition to the host rock. There were detectable primarily by a lack of iron, an element present in the dolomite matrix. 

Scanning electron microscope imaging and energy-dispersive X-ray spectroscope elemental maps of fossils in polished slab. (1) Overview giga-macro photomosaic of a portion of polished thick section; labelled rectangles correspond to scanning electron microscope imaging and energy-dispersive X-ray spectroscope elemental maps image regions as indicated. (2), (3) Silicified fossil in transverse section: (2) backscattered electron (z-contrast) image, with (3) corresponding overlain elemental maps for calcium, silicon, and iron. (4), (5) Calcareous fossil in transverse section: (4) Backscattered electron (z-contrast) image, with (5) corresponding overlain elemental mabs for calcium, silicon, and iron. Scale bars are 5 mm (1), and 500 μm (2), (5). Schiffbauer et al. (2024).

The La Ciénega fauna was first described in 1985 by palaeontologist Mark McMenamin of Mount Hollyoak College, who assigned the fossils to a group of morphotypes rather than trying to assign them to taxa, and believed the sediments to be Early Cambrian in age, at least in part because PreCambrian fossils were thought to be extremely rare (if accepted at all) at this time. Subsequently, some of the fossils were identified as Sinotubulites, an exclusively PreCambrian taxa (the Ediacaran Period had not been named as such at this time), although this led to the postulation that this taxon extended into the Cambrian, as this was the data assigned to the La Ciénega Formation. It was not until the recognition of Cloudina, also exclusively PreCambrian, and later an index fossil for the Terminal Ediacaran, that the La Ciénega Formation was recognised as PreCambrian in origin, with geochemical dating methods later confirming an End Ediacaran age.

Schiffbauer et al. interpret the La Ciénega fauna as a multi-taxa, Terminal Ediacaran assemblage, including Sinotubulites, Cloudina, and other Cloudinomorphs, probably Saarina or Conotubus, as well as other, unidentified tubular fossils. The preservation present is a mixture of silicification, which produces fossils recoverable by acid etching, and calcification, which does not. Many of the silicified fossils show plastic deformation, which is taken to indicate that they were not silicified in life, but rather as the result of some taphonomic process. Examined in thin section, the calcified specimens appear to show finer organic structures, supporting this hypothesis. This means that identification of the fossils from the silicified material only is unreliable. However, the preservation of what appear to be drill holes in some of these fossils, and the fact that these drill holes only appear to be present in examples of Cloudina and not Sinotubulites is likely to be significant, as this repeats a pattern seen in deposits of a similar age in Shaanxi Province, China, increasing the possibility that this represents some form of early predator-prey interaction, with predators able to select certain tubes as suitable targets for predation.

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Pheidole praehistorica: A new species of Spiny Ant from Oligo–Miocene Chiapas Amber.

The genus Pheidole is currently considered to be the most diverse genus of Ants, with 1160 living and six fossil species. Although global in distribution, the genus is at its most diverse in the Neotropics, and is presumed to have originated in this region. This is supported by the locations from which the known fossils in the genus have been recovered, with the oldest known species coming from the Eocene of Colorado, and other fossils known from the Miocene of the Dominican Republic (three species), and the Oligo-Miocene of Chiapas State, Mexico (2 species).

In a paper published in the European Journal of Taxonomy on 25 October 2024, Fernando Varela-Hernández & Franciso Riquelme of the Laboratorio de Sistemática Molecular at the Universidad Autónoma del Estado de Morelos, describe a third species of Pheidole from Chiapas Amber.

Chiapas Amber comes from the Simojovel, Totolapa, and Estrella de Belén localities in the Chiapas Highlands of southern Mexico, with the Simojovel site being the main centre of commercial amber extraction. The amber comes from a series of limestone, sandstone, siltstone, shale, and lignite beds of Late Oligocene to Early Miocene age, referred to as either the Simojovel Formation or the La Quinta Formation. The amber here is thought to have derived from a type of Leguminous tree of the genus Hymenaea; resin-producing trees belonging to this genus are also thought to have been responsible for Dominican Amber, which is of approximately the same age as Chiapas Amber, and are still found today across the Neotropics. 

The new species is named Pheidole praehistorica, where 'praehistorica' means 'prehistoric' in reference to the nature of the material from which it is described, five fossil Ants trapped within a single species of amber.

Pheidole praehistorica. (A)–(C) Holotype (CPAL.464). (A) Profile view. (B) Frontal view. (C) Closer lateral view of the head and mesosoma. (D) Paratype (CPAL.465), latero-frontal view of the head. (E) Paratype (CPAL.468), profile view. Abbreviations: acl, antennal club; an, antenna; cly, clypeus; ey, eyes; fl, foreleg; ga, gaster; ha, hairs on clypeus; hd, head; hl, hind  leg; mn,  mandible; nck, neck; p, petiole; pn, pronotum; pns, pronotal spine; pp, postpetiole; pps, propodeal spine; sc, scape. Varela-Hernández & Riquelme (2024).

Pheidole praehistorica is smaller than other species from Chiapas Amber, an average length of 2.3 mm, and has shorter pronotal spines (spines on the forward part of the thorax, immediately behind the head) and straight propodeal spines (spines on the rear part of the thorax, immediately before the abdomen. 

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