A new stem cheloniid turtle, Cabindachelys landanensis, gen. et sp. nov., is represented by a nearly complete skull and partial hyoid collected in lower Paleocene shallow marine deposits, equivalent to the offshore Landana Formation, near the town of Landana in Cabinda, Angola. A partial chelonioid carapace previously reported from this locality is referred here to C. landanensis. Cabindachelys landanensis possesses clear synapomorphies of Pan-Cheloniidae, including a rod-like rostrum basisphenoidale, V-shaped basisphenoid crest, and secondary palate, but also retains a reduced foramen palatinum posterius, unlike most other pan-cheloniids. Phylogenetic analysis suggests that C. landanensis forms a weakly-supported clade with Erquelinnesia gosseleti, Euclastes acutirostris, Euclastes wielandi and Terlinguachelys fischbecki, although a close relationship between the protostegid T. fischbecki and these durophagous pan-cheloniids is unlikely. The Paleocene–Eocene strata near Landana have produced a number of turtle fossils, including the holotype specimen of the pleurodire Taphrosphys congolensis. A turtle humerus collected c. 1 m above the holotype skull of C. landanensis differs from humeri of chelonioids and Taphrosphys, indicating that a third turtle taxon is present at Landana. Cheloniid fossil material is rare in the Landana assemblage, in comparison with the abundant remains of Taphrosphys congolensis found throughout the stratigraphic section. This disparity implies that C. landanensis preferred open marine habitats, whereas Taphrosphys congolensis spent more time in nearshore environments. The appearance of new durophagous species such as C. landanensis in the early Paleocene reflects the rapid radiation of pan-cheloniids as they diversified into open niches following the K–Pg extinction.

We report a new chelonioid turtle on the basis of a nearly complete skull collected in lower Paleocene, shallow marine deposits, equivalent to the offshore Landana Formation, near the town of Landana in Cabinda Province, Angola. Chelonioid material previously reported from this locality is likely referable to this new taxon. The well-preserved skull is missing the left quadrate, squamosal, and prootic, both opisthotics, and the mandible. The skull possesses a rod-like basisphenoid rostrum, which is a synapomorphy of Chelonioidea, but it differs from other chelonioid skulls in that the contact between the parietal and squamosal is absent, and the posterior palatine foramen is present. Phylogenetic analysis recovers the new taxon as a basal chelonioid. The Paleocene– Eocene strata near Landana have produced a wealth of turtle fossils, including the holotype of the pleurodire Taphrosphys congolensis. A turtle humerus collected from the Landana locality differs morphologically from the humeri of chelonioids and Taphrosphys, indicating the presence of a third taxon. Chelonioid fossil material in the Landana assemblage is rare compared to the abundant fragmentary remains of Taphrosphys that are found throughout the stratigraphic section. This disparity in abundance suggests the new chelonioid taxon preferred open marine habitats, whereas Taphrosphys frequented nearshore environments.

In this paper we present a method for estimating soil pCO2 in ancient environments using the measured carbon-isotope values of pedogenic carbonates and plant-derived organic matter. The validity of soil pCO2 estimates proves to be highly dependent on the organic δ13C values used in the calculations. Organic matter should be sourced from the same paleosol profiles as sampled carbonates to yield the most reliable estimates of soil pCO2. In order to demonstrate the potential use of soil pCO2 estimates in paleoecological and paleoenvironmental studies, we compare samples from three Upper Jurassic localities. Soil pCO2 estimates, interpreted as a qualitative indicator of primary paleoproductivity, are used to rank the Late Jurassic terrestrial environments represented by the Morrison Formation in western North America, the informally named Lourinhã formation in Western Europe, and the Stanleyville Group in Central Africa. Because modern terrestrial environments show a positive correlation between primary productivity and faunal richness, a similar relationship is expected in ancient ecosystems. When the relative paleoproductivity levels inferred for each study area are compared with estimates of dinosaur generic richness, a positive correlation emerges. Both the Morrison and Lourinhã formations have high inferred productivity levels and high estimated faunal richness. In contrast, the Stanleyville Group appears to have had low primary productivity and low faunal richness. Paleoclimatic data available for each study area indicate that both productivity and faunal richness are positively linked to water availability, as observed in modern terrestrial ecosystems.

Investigation of the palaeoclimatic conditions associated with Upper Jurassic strata in Portugal and comparison with published palaeoclimate reconstructions of the Upper Jurassic Morrison Formation in western North America provide important insights into the conditions that allowed two of the richest terrestrial faunas of this period to flourish. Geochemical analyses and observations of palaeosol morphology in the informally named Upper Jurassic Lourinhã formation of western Portugal indicate warm and wet palaeoclimatic conditions with strongly seasonal precipitation patterns. Palaeosol profiles are dominated by carbonate accumulations and abundant shrink-swell (vertic) features that are both indicative of seasonal variation in moisture availability. The δ18OSMOW and δDSMOW values of phyllosilicates sampled from palaeosol profiles range from +22·4‰ to +22·7‰ and −53·0‰ to −37·3‰, respectively. These isotope values correspond to temperatures of formation between 32°C and 39°C ± 3°, with an average of 36°C, which suggest surface temperatures between 27°C and 34°C (average 31°C). On average, these surface temperature estimates are 1°C higher than the highest summer temperatures modelled for Late Jurassic Iberia using general circulation models. Elemental analysis of matrix material from palaeosol B-horizons provides proxy (chemical index of alteration minus potassium) estimates of mean annual precipitation ranging from 766 to 1394 mm/year, with an average of approximately 1100 mm/year. Palaeoclimatic conditions during deposition of the Lourinhã formation are broadly similar to those inferred for the Morrison Formation, except somewhat wetter. Seasonal variation in moisture availability does not seem to have negatively impacted the ability of these environments to support rich and relatively abundant faunas. The similar climate between these two Late Jurassic terrestrial ecosystems is probably one of the factors which explains the similarity of their vertebrate faunas.

We report a new chelonioid turtle on the basis of a nearly complete skull collected in lower Paleocene, shallow marine deposits, equivalent to the offshore Landana Formation, near the town of Landana in Cabinda Province, Angola. Chelonioid material previously reported from this locality is likely referable to this new taxon. The well-preserved skull is missing the left quadrate, squamosal, and prootic, both opisthotics, and the mandible. The skull possesses a rod-like basisphenoid rostrum, which is a synapomorphy of Chelonioidea, but it differs from other chelonioid skulls in that the contact between the parietal and squamosal is absent, and the posterior palatine foramen is present. Phylogenetic analysis recovers the new taxon as a basal chelonioid. The Paleocene– Eocene strata near Landana have produced a wealth of turtle fossils, including the holotype of the pleurodire Taphrosphys congolensis. A turtle humerus collected from the Landana locality differs morphologically from the humeri of chelonioids and Taphrosphys, indicating the presence of a third taxon. Chelonioid fossil material in the Landana assemblage is rare compared to the abundant fragmentary remains of Taphrosphys that are found throughout the stratigraphic section. This disparity in abundance suggests the new chelonioid taxon preferred open marine habitats, whereas Taphrosphys frequented nearshore environments.