Tepexi De Research Articles

A New World macrosemiid (Pisces: Neopterygii—Halecostomi) from the Albian of Mexico

ABSTRACT A new genus and species belonging to the Macrosemiidae is described. This is the first record of a macrosemiid in the New World. The material was collected from the Early Cretaceous (Albian) Tlayúa Quarries, in Tepexi de Rodríguez, central México. The new taxon is a small, elongated fish that bears a combination of apomorphic and plesiomorphic characters including a divided dorsal fin with an area devoid of scales on either side, prearticular and coronoid bones with small pointed teeth, and strongly ornamented body scales. Phylogenetic analysis using PAUP revealed a close relationship of this new genus to Macrosemius and Legnonotus. The occurrence of macrosemiids in the Tlayúa beds indicates a wider distribution of the group within the Tethys Ocean, and represents the westernmost record of this group of neopterygians.

Genesis of a locality of exceptional fossil preservation: paleoenvironments of Tepexi de Rodrı́guez (mid-Cretaceous, Puebla, Mexico)

This study of Tepexi de Rodrı́guez (Puebla, Mexico), a mid-Cretaceous (Aptian?) locality with exceptional fossil preservation, combines statistically based microfacies-transition analysis with spectral analysis of depth-series measurements, in an attempt to constrain the paleoenvironmental setting. Tepexi de Rodrı́guez (Tepexi) is largely composed of laminated micrites, and presents a complex amalgam of primary and diagenetically altered fabrics. Modified Markov analysis of microfacies successions was used to assess repetitive patterns among primary microfacies. The reconstructed microfacies succession indicates recurring upward-fining sequences. Spectral analysis of depth-series measurements of magnetic susceptibility and RGB visible color (redness) reveals a pattern of repetition in the sedimentary sequence that is concordant with patterns of Milankovitch cyclicity. Strong eccentricity, obliquity, and semi-precessional signals are inferred. This suite of Milankovitch cyclicities is attributed to double-monsoon influences on Tepexi from both the northern and southern hemispheres, and implies an average rock accumulation rate of 2.0 cm/kyr. Previous reconstructions of Tepexi (e.g. a variety of back-reef lagoonal settings) do not match the observations reported here. Likewise, tidally influenced deposition is ruled out. Tepexi de Rodrı́guez appears to have been an open marine basin with storm-dominated sedimentation and bottom waters with restricted circulation. The fossil biota has a strong terrestrial influence, indicating that land was close by.

The Fossil Record of Vertebrate Tracks in Mexico

The fossil record of vertebrate tracks in Mexico is taxonomically rich and geographically diverse, and ranges in age from Middle Jurassic to Pleistocene and possibly Holocene. Middle Jurassic saurischian dinosaur tracks from Oaxaca represent the oldest record of vertebrate tracks in Mexico. Tracks attributed to Late Jurassic theropods and ornithopods are known from Michoacán. Theropod tracks of supposed Jurassic age are known from Durango. Lower Cretaceous Saurischian and ornithopod tracks are known from southern Puebla. Central Mexico has yielded Late Cretaceous hadrosaurid and sauropod tracks (Puebla), and tracks belonging to Theropoda and Ornithopoda (El Aguaje, Michoacan). In Coahuila several tracksites occur within the Cerro del Pueblo Formation and include tracks of mesoreptiles, pterosaurs, small to large theropods, bipedal and quadrupedal ornithopods, birds and possibly a mammal. A tracksite in the Olmos Formation includes tracks of turtles, crocodilians, medium-sized theropods, small ornithopods, and birds. Bird tracks of supposed Eocene age are known from Sinaloa. Two important Pleistocene ichnofaunas occur in the states of Puebla (Tepexi de Rodríguez) and Jalisco (San Juan de los Lagos), and include tracks of camelids, artiodactyls, small ungulates, elephants, large felids and birds. Pleistocene human tracks occur in Coahuila and Jalisco. Mexico's track record provides important insights into vertebrate diversity, paleoecology, and paleoenvironments. Given the rate of new discoveries since 1998, there is no doubt that new sites await to be found.

Cretaceous belemnites of Mexico III. The Albian Neo- and Mesohibolites of the ``Mexican Solnhofen`` Tepexi de Rodríguez (State of Puebla) and their biostratonomy (Lower Cretaceous)

Cretaceous belemnites of Mexico III. The Albian Neo- and Mesohibolites of the ``Mexican Solnhofen`` Tepexi de Rodríguez (State of Puebla) and their biostratonomy (Lower Cretaceous)

New Cuvieronius finds from the Pleistocene of central Mexico

In the southern part of the State of Puebla, central Mexico, the town of Tepexi de Rodriguez is a well-known fossiliferous area because of the beautiful and extraordinary Early Cretaceous vertebrates recovered from the Tlayua Quarry (Applegate, 1996; Espinosa-Arrubarrena and Applegate, 1996; Reynoso-Rosales, 1996a, 1996b, 1997, among others), and a Tertiary plant locality known as “Los Ahuehuetes” (Magallón-Puebla and Cevallos-Ferriz, 1994; Velasco de León and Cevallos-Ferriz, 1997; Ramírez-Garduño, 1998, among others). The Axamilpa river drains this area and along its banks a sequence of Late Cenozoic sands, silts, and gravels are exposed. In these sediments scattered fossil mammalian remains had been recovered (Torres-Martínez and Agenbroad, 1991; Montellano-Ballesteros and Castro-Azuara, 1996; Fig. 1).

NEW CUVIERONIUS FINDS FROM THE PLEISTOCENE OF CENTRAL MEXICO

In the southern part of the State of Puebla, central Mexico, the town of Tepexi de Rodriguez is a well-known fossiliferous area because of the beautiful and extraordinary Early Cretaceous vertebrates recovered from the Tlayua Quarry (Applegate, 1996; Espinosa-Arrubarrena and Applegate, 1996; Reynoso-Rosales, 1996a, 1996b, 1997, among others), and a Tertiary plant locality known as “Los Ahuehuetes” (Magallón-Puebla and Cevallos-Ferriz, 1994; Velasco de León and Cevallos-Ferriz, 1997; Ramírez-Garduño, 1998, among others). The Axamilpa river drains this area and along its banks a sequence of Late Cenozoic sands, silts, and gravels are exposed. In these sediments scattered fossil mammalian remains had been recovered (Torres-Martínez and Agenbroad, 1991; Montellano-Ballesteros and Castro-Azuara, 1996; Fig. 1).

A diverse assemblage of Anacardiaceae from Oligocene sediments, Tepexi de Rodriguez, Puebla, Mexico

Among the plants collected from the Pie de Vaca Formation of the Oligocene, of Tepexi de Rodríguez, Puebla, México are five plants of Anacardiaceae, Haplorhus medranoensis, Rhus toxicodendron, Rhus sp., Comocladia intermedia, and Pistacia marquezii represented by their leaves and/or leaflets. The past and present diversity and geographic distribution of one of these genera, Rhus, demonstrate its capability to adapt and diversify in a wide variety of environments. Leaf architecture characters of this taxon overlap with those of other genera in the family, suggesting a high degree of phenotypic plasticity. The presence in the Pie de Vaca Formation of a type of Pistacia with leaf architecture characters similar to those of Asian plants further supports a long history of exchange between low-latitude North America and Asia. Links between low-latitude North and South America and the Caribbean are suggested by the presence of Comocladia and Haplorhus. Whereas Comocladia highlights the long history of regional endemics in the area, Haplorhus, today an endemic monotypic genus of Peru, suggests exchange mechanisms between North and South America. The morphologic characters of these taxa, and those of Pseudosmodingium (Anacardiaceae), some Rosaceae, Leguminosae, and Berberidaceae, suggest that the Pie de Vaca community was established and evolved in harsh environmental conditions. The Pie de Vaca flora thus provides significant new insights into the biogeographic relationships of the low latitude vegetation of North America.

A new scincomorph lizard from the Early Cretaceous of Puebla, Mexico

Abstract A complete skeleton of a new scincomorph lizard from the Early Cretaceous deposits of Tepexi de Rodriguez is described. Tepexisaurus tepexii gen. et sp. nov. is the best preserved early scincomorph and the first known taxon that is morphologically primitive to scincoids and paramacellodid lizards. The presence of pointed ventral parietal downgrowths, the coronoid overlapped anteriorly and posteriorly by the dentary and surangular, a small medial flange on the retroarticular process, and weak zygosphene and zygantrum articulations suggest scincoid relationships, but the absence of ventral and dorsal osteoscutes place Tepexisaurus as sister-group of this taxon. It shares the presence of ±30 closely packed teeth with the poorly known Upper Jurassic genus Saurillus and Pseudosaurillus , but differences in the coronoid structure, Meckelian groove and jaw proportions indicate that both taxa are distinct. Similar to Tepexisaurus , the absence of osteoscutes in Saurillus , Pseudosaurillus and Saurillodon place these taxa in a more primitive position relative to other paramacellodids which should be included within Scincoidea. Thus, Paramacellodidae as previously defined is a paraphyletic assemblage. The late presence of a pre-scincoid lizard in the Albian deposits of Tlayua can be correlated with the presence of sphenodontians and the relictual nature of the basal squamate Huehuecuetzpalli mixtecus . It gives additional evidence to support the hypothesis that Tlayua was a refuge for terrestrial archaic forms during the Albian.

A new scincomorph lizard from the Early Cretaceous of Puebla, México

A complete skeleton of a new scincomorph lizard from the Early Cretaceous deposits of Tepexi de Rodrı́guez is described. Tepexisaurus tepexii gen. et sp. nov. is the best preserved early scincomorph and the first known taxon that is morphologically primitive to scincoids and paramacellodid lizards. The presence of pointed ventral parietal downgrowths, the coronoid overlapped anteriorly and posteriorly by the dentary and surangular, a small medial flange on the retroarticular process, and weak zygosphene and zygantrum articulations suggest scincoid relationships, but the absence of ventral and dorsal osteoscutes place Tepexisaurus as sister-group of this taxon. It shares the presence of ±30 closely packed teeth with the poorly known Upper Jurassic genus Saurillus and Pseudosaurillus, but differences in the coronoid structure, Meckelian groove and jaw proportions indicate that both taxa are distinct. Similar toTepexisaurus , the absence of osteoscutes in Saurillus, Pseudosaurillus and Saurillodon place these taxa in a more primitive position relative to other paramacellodids which should be included within Scincoidea. Thus, Paramacellodidae as previously defined is a paraphyletic assemblage. The late presence of a pre-scincoid lizard in the Albian deposits of Tlayua can be correlated with the presence of sphenodontians and the relictual nature of the basal squamateHuehuecuetzpalli mixtecus . It gives additional evidence to support the hypothesis that Tlayua was a refuge for terrestrial archaic forms during the Albian.

Leaves of Cercocarpus mixteca n. sp. (Rosaceae) from Oligocene sediments, near Tepexi de Rodrı́guez, Puebla

A new species of Cercocarpus, Cercocarpus mixteca Velasco de León & Cevallos-Ferriz, is described based on leaf impressions from the Los Ahuehuetes locality, near Tepexi de Rodrı́guez, Puebla, Mexico. The lamina is obovate, 1.3 cm in length by 0.5 cm in width, has a serrate margin in its distal fourth, craspedodromous venation with a single straight mid-vein and two to four pairs of secondary ones, and areols that tend to be quadrangular in shape. A phenetic analysis of the agglomerative, non-hierarchical type, with mean linkage, is applied using 22 OTUs and 34 character states. The morphological characters observed on the leaves of the new fossil plants support the recognition of a new taxon closely related to the extant Cercocarpus paucidentatus growing naturally in northern Mexico. Its microphyll size corresponds with the temperate to xeric climate postulated for the Los Ahuehuetes locality; this further suggests that some taxa, like Cercocarpus, have a long history in low latitude North America. In this particular case, the extant Cercocarpus fothergilloides and Cercocarpus macrophyllus could, as they were able to colonise new humid and xeric areas, represent descendants of C. mixteca.

Leaves of Berberidaceae ( Berberis and Mahonia) from Oligocene sediments, near Tepexi de Rodrı́guez, Puebla.

From the Oligocene Los Ahuehuetes locality, near Tepexi de Rodrı́guez, Puebla, Mexico, five new plant species are described based on their leaf architecture. The presence of brochidodromous or acrodromous venation, and secondary veins forming angular (versus rounded) arcs, are well defined characters in the fossil material that relate it to Berberidaceae. Comparison with the leaves and leaflets of extant and fossil plants allow the recognition of one Mahonia and four Berberis new species. The lack of detailed information on leaf architecture in Berberidaceae limits the evaluation of the taxonomic relationships that can be suggested between fossil and extant plants. However, from a biogeographic point of view the presence of these new fossil plants supports the hypothesis of a North American origin of the Orientalis Groups of Mahonia, to which a lineage of Berberis may be added. Furthermore, two of the new species suggest the dispersal, some time during the Tertiary, of a lineage that today forms the Australis Group of Berberis from low latitude North America to South America. The movement of the Chortis Block is proposed as an alternative to explain the dispersal of a growing list of plants from north to south in the Americas. Only through future geological and palaeobotanical work can this hypothesis be corroborated.

PRESENTATION OF THE 1999 HARRELL L. STRIMPLE AWARD TO THE ARANGUTI FAMILY

At the end of 1981, my institution began a relationship with the Aranguti Family that has grown more intense with each passing year. It was during this time that we became aware of the lithographic limestone and flag stone quarries owned by the family, near the town of Tepexi de Rodriguez in the State of Puebla, about 220 km (138 miles) south east of Mexico City, in a region known as the Mixteca-Poblana. Today, we know that of the 15 great fossil localities of the world, the Tlayua quarry is certainly one of them. These remarkable deposits, no larger than two football fields, are of middle to late Albian age, and so far have produced well over 5,500 fossils that are housed in the Paleontological Collections of the Geological Institute at the National University of Mexico. The number of new forms continues to grow every month. How did this come about? Basically, through the generosity, keen interest, and intelligence of the members of the family. A student at UNAM (Universidad Nacional Autonoma de Mexico) informed our staff about the fossils being found near Tepexi de Rodriguez, and ultimately …

Leaves of Salicaceae (Salix and Populus) from Oligocene Sediments Near Tepexi de Rodríguez, Puebla, Mexico.

Eleven new salicaceous taxa based on fossil leaves, seven Salix and four Populus species, are described from the Oligocene Los Ahuehuetes locality, Pie de Vaca Formation, near Tepexi de Rodríguez in Puebla, Mexico. They are characterized by the presence of typical salicoid teeth, camptodromous secondary venation, and elliptic or lanceolate shape. Morphological differences between these new fossil plants and those reported previously from the United States and elsewhere indicate that diversification among these taxa occurred early during their differentiation. Furthermore, the limited morphological similarities of the fossil and extant plants growing naturally in Mexico also indicate a high rate of evolution. Documenting the expansion of high-latitude North American taxa into lower latitudes at the time of deposition of the Pie de Vaca Formation confirms that at least some of the typical boreal taxa were part of dry tropical communities in low-latitude North America and underscores the need to reevaluate the origin of this southern vegetation.

Reconstruction of the Leaves of Two New Species of Pseudosmodingium (Anacardiaceae) from Oligocene Strata of Puebla, Mexico.

Leaves of two new plants are reconstructed from their isolated leaflets collected from the Oligocene Los Ahuehuetes locality near Tepexi de Rodríguez in Puebla, Mexico. The leaves of Pseudosmodingium mirandae Ramírez-Garduño et al. are compound imparipinnate with leaflets of variable morphology. The leaflets of five leaf morphotypes vary from narrow elliptic to lanceolate or lorate; they are symmetrical to slightly asymmetrical, with acute to attenuate apex, acute to cuneate base, and entire to serrate margin. Venation is simple pinnate craspedodromous, with secondary veins slightly curved near their base; secondary veins may dichotomize near the margin to become tertiary veins, and intersecondary veins are small and oblique to the secondary veins. A small number of leaflets assigned to Pseudosmodingium terrazasiae Ramírez-Garduño et al. are distinguished from P. mirandae by the leaflet shape, length&rcolon;width ratio, base shape, and apex angle. Morphological comparison of the fossil leaves with leaves of extant species of Anacardiaceae based on numerical analyses indicates a close similarity between P. mirandae and Pseudosmodingium multifolium Rose, while P. terrazasiae is more similar to Pseudosmodingium perniciosum (HBK) Engl. The presence of fossil species with extant relatives that are endemic to Mexico, along with previous reports, indicates that by the Oligocene, some lineages were already in place, although today they form part of the more xeric communities in southern North America.

An unusual aquatic sphenodontian (Reptilia: Diapsida) from the Tlayua Formation (Albian), Central Mexico

The sphenodontianAnkylosphenodon pachyostosusnew genus and species is the second unusual sphenodontian reported from the Albian deposits of the Tlayua Formation, near Tepexi de Rodríguez, Central Mexico. The skeleton is robust with pachyostotic ribs and vertebrae. Unique long teeth are ankylosed deep into the lower jaw extending close to the edge of the Meckelian canal. Long teeth with open roots, the lack of worn-out teeth, and the presence of posterior wear surfaces exhibiting dentine suggest that tooth growth was continuous. These features combined with a propalinal action of the deep lower jaw suggest herbivory. Herbivorous specializations ofAnkylosphenodonare different from the laterally expanded teeth ofToxolophosaurusandEilenodonand may have evolved to prevent total tooth loss, a feature which is observed in sapheosaurs. A pachyostotic skeleton, a delay of the ossification of the epiphyses, and a solid structure of the vertebral column could be related to a none obligated aquatic behavior. These specializations differ greatly from those of other aquatic sphenodontians such asPleurosaurusandPalaeopleurosaurus.A stout skeleton with swollen horizontal zygapophyses suggests affinities with sapheosaurs; however, cladistic analysis support sister-group relationship withToxolophosaurusand/orEilenodonon the basis of shared propalinal jaw action and deep jaws. The presence of two unique sphenodontians in the Tlayua Quarry suggests the presence of an area for the diversification of lepidosaur reptiles. The late presence of sphenodontians in the Albian also suggests that this area was a refuge for archaic forms at the time.

AN UNUSUAL AQUATIC SPHENODONTIAN (REPTILIA: DIAPSIDA) FROM THE TLAYUA FORMATION (ALBIAN), CENTRAL MEXICO

The sphenodontian Ankylosphenodon pachyostosus new genus and species is the second unusual sphenodontian reported from the Albian deposits of the Tlayua Formation, near Tepexi de Rodriguez, Central Mexico. The skeleton is robust with pachyostotic ribs and vertebrae. Unique long teeth are ankylosed deep into the lower jaw extending close to the edge of the Meckelian canal. Long teeth with open roots, the lack of worn-out teeth, and the presence of posterior wear surfaces exhibiting dentine suggest that tooth growth was continuous. These features combined with a propalinal action of the deep lower jaw suggest herbivory. Herbivorous specializations of Ankylosphenodon are different from the laterally expanded teeth of Toxolophosaurus and Eilenodon and may have evolved to prevent total tooth loss, a feature which is observed in sapheosaurs. A pachyostotic skeleton, a delay of the ossification of the epiphyses, and a solid structure of the vertebral column could be related to a none obligated aquatic behavior. These specializations differ greatly from those of other aquatic sphenodontians such as Pleurosaurus and Palaeopleurosaurus. A stout skeleton with swollen horizontal zygapophyses suggests affinities with sapheosaurs; however, cladistic analysis support sister-group relationship with Toxolophosaurus and/or Eilenodon on the basis of shared propalinal jaw action and deep jaws. The presence of two unique sphenodontians in the Tlayua Quarry suggests the presence of an area for the diversification of lepidosaur reptiles. The late presence of sphenodontians in the Albian also suggests that this area was a refuge for archaic forms at the time.

Leaves ofKarwinskia axamilpensesp.nov. (Rhamnaceae) from Oligocene sediments, near Tepexi de Rodríguez, Puebla, Mexico

A new plant from the Los Ahuehuetes locality, near Tepexi de Rodríguez, Puebla, Mexico, is described based on its leaves. They are characterized by being ovate to elliptic, 4.5 cm long by 2.1 cm wide, having an entire margin, eucamptodromous venation, a midvein that is slightly curved and attenuated towards the leaf apex, seven pairs of secondary veins diverging at an acute angle from the midvein, percurrent tertiary veins forking or sometimes reticulated forming areoles, and having a petiole 1.3 cm long and 0.3 cm wide. An agglomerative nonhierarchical analysis with average linkage, based on the definition of 41 character states in 18 operational taxonomic units allows distinction between Karwinskia, Berchemia, and Rhamnus; the recognition of an extinct monotypic genus, Berhamniphyllum; and the identification of two fossil species of Karwinskia, among which the new plant from Puebla, Karwinskia axamilpense Velasco de León et al., is well defined. This new fossil leaf not only adds to the recently known Tertiary plants of the Los Ahuehuetes locality, but it gives new insights into the past flora of tropical North America and further supports the long history of some neotropical endemics, suggesting that, during the Tertiary, at least some areas in southern latitudes of North America could have been important for the origin and radiation of some taxa.Key words: Oligocene, Mexico, paleobotany, Rhamnaceae, Karwinskia.

Seven New Taxa of Holothurians (Holothuroidea: Echinodermata) From the Lower Cretaceous (Albian) Tlayua Quarries, Near Tepexi De Rodriguez, Puebla, Mexico

Seven New Taxa of Holothurians (Holothuroidea: Echinodermata) From the Lower Cretaceous (Albian) Tlayua Quarries, Near Tepexi De Rodriguez, Puebla, Mexico

Fossil legume fruits from tertiary strata of Puebla, Mexico

A small assemblage of fossil legume fruits, leaf fragments, and leaflets has been recovered from the Tertiary (Oligocene) "Los Ahuehuetes" flora near the town of Tepexi de Rodríguez, Puebla, in south-central Mexico. Five legume fruits are described and compared with fruits of extant genera. Four fruit types were identified as belonging to the modern genera Prosopis (Mimoseae; Mimosoideae), Mimosa (Mimoseae; Mimosoideae), Lysiloma (Ingeae; Mimosoideae), and Sophora (Sophoreae; Papilionoideae). Another fruit exhibits a combination of characters unknown among extant legumes, and although superficially similar to some species of Papilionoideae, it represents an extinct genus. The four identified genera are diverse in the extant vegetation of Mexico; in fact, Mexico represents an important area of distribution for them. The presence of Prosopis, Mimosa, Lysiloma, and Sophora in the fossil flora of Puebla documents the occurrence of these genera in this part of their present area of distribution by the Oligocene. The climatic affinities of modern species of Mimosa, Lysiloma, and Sophora are so varied as to preclude any useful paleoclimatic inference. Prosopis is regularly associated with arid environments; however, the genus has been reported from fossil localities where humid conditions prevailed. This observation, together with the assemblage of plants that co-occur in the Los Ahuehuetes flora, suggests that plant communities of the past may have been composed, at least partly, of elements that today are associated with different habitats and environmental conditions. The fossil legume fruits from Los Ahuehuetes flora add to the previously known diversity of Leguminosae by the Tertiary, confirm tropical America as one of the important areas of radiation and diversification for Leguminosae, and contribute to the knowledge of Tertiary floras of southern North America. Key words: Leguminosae, Tertiary, Mexico, paleobotany, fossil legume.

New Findings on the Origins of Thin Orange Ceramics

AbstractNew data are presented from a settlement pattern survey of the Tepexi de Rodríguez region of southern Puebla, Mexico, and from excavations of two ceramic Workshops where Thin Orange ceramics, “Teotihuacan's most important trade ware,” were manufactured. Results of the settlement pattern survey reveal that the Tepexi de Rodríguez region, where the trade ware was made, had a flourishing civilization during the Classic period (a.d. 300–750) which enjoyed continuous, intensive contact with Teotihuacan, yet the region was apparently not under the domination of the Teotihuacan state. Data are presented on the techniques of ceramic manufacture, the contexts of pottery production, and the social and economic organization of the potters who made Thin Orange ceramics.