Search

The northeastern part of Algeria is characterized by Meso–Cenozoic fossiliferous deposits. All the previous studies have been focused on invertebrate and vertebrate body fossils from this region. In the present paper we provide the first ichnological study from the region of Ouenza, Tebessa Wilaya (northeastern Algeria). An ichnoassemblage composed of eight ichnotaxa, namely cf. Archaeonassa isp., Arenicolites isp., Diplocraterion isp., Helminthopsis isp., Palaeophycus tubularis, Skolithoscf. linearis, cf. Taenidium isp., and Thalassinoides isp., reported from the lower Langhian (Middle Miocene) of Aïn Sidi Salah locality (Tebessa Basin) is discussed. These trace-fossils belong to the Skolithos and proximal Cruziana ichnofacies indicating deposition within a shallow marine (littoral). The large size of Thalassinoides suggests well-oxygenated setting, under moderate- to high-energy conditions, with occasional storm events. Keywords: trace-fossils, paleoenvironments, shallow marine, Middle Miocene, Tebessa.

Late Cretaceous carbonate rocks of the Eagle Ford Formation are widely distributed in north-western Mexico (Nuevo Leon, Coahuila, Chihuahua) and southern USA (Texas). Around the La Bolita locality, Castanos town (Coahuila State), this unit consists of approximately 31 m of marine deposits, characterized by thin-bedded, slightly clayey limestones. Within the scope of a microfacial analysis, 20 hand samples were collected from selected limestone levels. Identified microfossil remains are mostly represented by planktonic foraminifers, among which: Planoheterohelix moremani, P. reussi, P. globulosa, Globigerinelloides bollii, Globigerinelloides spp., Muricohedbergella delrioensis, M. planispira, Muricohedbergella spp., Whiteinella archaeocretacea, W. aprica, W. baltica, W. brittonensis, W. inornata, W. paradubia, Whiteinella spp., Clavihedbergella moremani, C. simplex, Marginotruncana renzi, M. sigali, M. schneegansi, M. pseudolinneiana, Marginotruncana spp., Praeglobotruncana algeriana, and Dicarinella canaliculata. There are also abundant calcispheres, such as Risserella rablingae, Pithonella ovalis, and Calcisphaerula innominata; as well as roveacrinoid ossicles (genus Roveacrinus), and unidentified radiolarians. Based on the stratigraphic range of both the genus Marginotruncana and the species Praeglobotruncana algeriana, an early–middle Turonian age is assigned to the studied section. The pelagic microfossil assemblage and the lithological features all suggest deposition of the studied sediments in an open marine platform, with poorly oxygenated, nutrient-rich waters.

This paper documents the occurrence of Skolithos linearis, Planolites beverleyensis, and Thalassinoides isp. in the Cárdenas Formation (Late Cretaceous), southeastern San Luis Potosí, central Mexico. This is the second record of S. linearis for this lithological unit, while P. beverleyensis and Thalassinoides isp. are documented for the very first time in this formation. The ichnoassemblage is referred to the Cruziana Ichnofacies which, in concert with associated invertebrate body fossils (Exogyra costata), suggest a shoreface setting with moderate- to low-energy conditions and episodic storms.

The fossil-rich limestones (La Negra Facies of the El Doctor Formation) in the Muhi Quarry, northwestern State of Hidalgo, Mexico are of late Albian age based on the occurrence of the ammonites Mortoniceras sp., Hamites aff. renzi and ?Beudanticeras sp. Their occurrence establishes the possible presence of the M. fallax, M. rostratum, M. prinflatum, and A. briacensis Zones (upper Albian) in North America. The late Albian age of the El Doctor Formation makes its teleostean aulopiforms and acanthomorphs the oldest in the world and the occurrence of the chondrichthyans Ptychodus decurrens and Squalicorax falcatus, and the teleostean Tselfatiiformes are their oldest records in Mexico.

The Santa María Amajac paleolake is located in the central portion of Hidalgo, Mexico. Twenty-seven fossil taxa of aquatic and terrestrial plants, gastropods, ostracods, amphibians, and mammals identified previously in the area of the paleolake were selected and their distribution in America during the Late Pliocene- Pleistocene was analyzed using the panbiogeographic method. As a result of the overlap of 27 individual tracks, 5 generalized tracks were obtained: I) Western North American, II) Central North American, III) Eastern North American, IV) Mesoamerican, and V) South American. The generalized tracks are consistent with previous proposals for extant gymnosperms, amphibians, sauropsids, birds, mammals, aquatic plants, insects, beetles, and nematodes, suggesting that distribution patterns have prevailed since the late Pliocene (Blancan). Four biogeographic nodes were identified, 2 situated in North America, in California and Colorado, the third located in the Santa María Amajac area in central Mexico, and the fourth located in Central America.