First report of theropods from the Tacuarembó Formation (Late Jurassic-Early Cretaceous), Uruguay

Dinosaur remains from the lower part of the Tacuarembó Formation, Uruguay, consist of the isolated theropod teeth described here. This is the first record of this group in the Tacuarembó Formation and represents the oldest dinosaur remains from Uruguay.     

Elasmosaurs (Sauropterygia,Plesiosauria) from the La Colonia Formation (Campanian–Maastrichtian), Argentina

O’Gorman, J.P., Salgado, L., Varela, J., & Parras, A., 2013. Elasmosaurs (Sauropterygia, Plesiosauria) from the La Colonia Formation (Campanian–Maastrichtian), Argentina. Alcheringa 37, 257–265. ISSN 0311-5518.

Elasmosaur postcranial remains from the La Colonia Formation (Campanian–Maastrichtian), Chubut Province, Patagonia, Argentina, are described. The new material has small dimensions and caudal vertebrae with parapophyses strongly projected laterally—characters shared with some Elasmosauridae indet. from the coeval Allen Formation, Río Negro Province, Argentina. These features reinforce the similarities between the plesiosaur faunas to the north and south of the Somún Curá Plateau. The small size of these elasmosaurs may be palaeoecologically related to the marginal marine depositional environment of the sedimentary host rocks.

José P. O’Gorman [joseogorman@fcnym.unlp.edu.ar], División Paleontología Vertebrados, Museo de La Plata, Universidad Nacional de La Plata, Paseo del Bosque s/n., B1900FWA, La Plata, Argentina and [CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas)]; Leonardo Salgado [salgadoleito@yahoo.com.ar], Instituto de Investigación en Paleobiología y Geología, Universidad Nacional de Río Negro, Isidro Lobo y Belgrano, 8332 General Roca, Argentina and [CONICET]; Julio Varela [julioadrianvarela@hotmail.com], and Ana Parras [aparras@exactas.unlpam.edu.ar], INCITAP (CONICET-UNLPam), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de La Pampa, Uruguay 151, 6300 Santa Rosa, La Pampa, Argentina. Received 27.7.2012; revised 19.10.2012; accepted 27.10.2012.     

A new ‘bone-cracking’ dasyurid (marsupialia), from the Miocene of Riversleigh,northwestern Queensland

Ganbulanyi djadjinguli gen. et sp. nov. is described on the basis of an upper molar and premolar from an early-late Miocene site in Riversleigh, northwestern Queensland. The paucity of material constrains certainty in the determination of it's phylogenetic position. But, among dasyuromorphians, and dependent on the interpretation of tooth homology, this species shows unequivocal synapomorphies only with the derived dasyurine Sarcophilus, and/or Barinya wangala, a possible sister taxon to the modern dasyurid radiation (i.e., Sminthopsinae, Phascogalinae, Dasyurinae). Other apomorphies, evident in G. djadjinguli, are common to both carnivorous thylacinids and dasyurids within the order. Some dental features of Ganbulanyi djadjinguli are treated as adaptations to a ‘bone cracking’ habitus. If this interpretation is correct, then this species represents the only pre-Pliocene Australian taxon known to occupy such a niche and perhaps the smallest specialist ‘bone-cracker’ within Mammalia.     

A new Early Permian bivalve fauna from the Río Genoa Formation,Patagonia, Chubut Province,Argentina

Fourteen Bivalvia species are described from the Lower Permian Río Genoa Formation, exposed in the southern Tepuel-Genoa Basin (Chubut Province, Argentina), of which one, Fletcheripecten genoensis, is new. The studied specimens are well preserved, retaining fine details of the ornament and shell morphology. Palaeotaxodonta is represented by two species of Nuculopsis and four species of Phestia; Pteriomorphia by five species in five genera; and Heteroconchia by three informal species. Most of the species recorded also occur in the northern part of Tepuel-Genoa Basin and allow demarcation of new and distinct marine intervals in the Río Genoa Formation, which was classically interpreted to represent continental deposits. The bivalve fauna confirms a Cisuralian (Early Permian) age for the Río Genoa Formation and offers potential for improved regional and global correlations.     

Angiosperm association from the Río Turbio Formation (Eocene–?Oligocene) Santa Cruz,Argentina: revision of Hünicken’s (1955) fossil leaves collection

Vento, B. &; Prámparo, M. B., January 2018. Angiosperm association from the Río Turbio Formation (Eocene–?Oligocene), Santa Cruz, Argentina: Revision of Hünicken’s (1955 Hünicken, M., 1955. Depósitos neocretácicos y terciarios del extremo S.S.W. de Santa Cruz: Cuenca Carbonífera de Río Turbio. Revista del Instituto Nacional de Investigacion de las Ciencias Naturales 4, 1–161. (in Spanish) [Google Scholar]) fossil leaves collection, Alcheringa 42, 125–153. ISSN 0311-5518.

The Río Turbio Formation (Eocene–?Oligocene) is of particular paleobotanical interest owing to its combination of high fossil plant diversity associated with the coexistence of warm-temperate and cool-temperate components. As the first suite of fossils related to a documented stratigraphic section, Hünicken’s fossil plant collection is one of the most important from the Paleogene of South America. A total of 34 angiosperm species from the collection were reviewed and taxonomically updated, with Nothofagus as the dominant genus. The taxa identified indicate a warm and humid climate with the development of some elements of a cool-temperate climate marked by a transitional climate change to cooler conditions. The comparison of angiosperms from different paleofloras from the southernmost of South America confirms that the assemblage of Río Turbio Formation was similar to that of the Río Pichileufú area, both from Patagonia, Argentina.

Bárbara Vento [bvento@mendoza-conicet.gov.ar] Mercedes B. Prámparo [mprampar@mendoza-conicet.gov.ar] Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA) CCT-CONICET, Mendoza, Adrián Ruiz Leal s/n, Casilla Correo 131, C5500, Mendoza, Argentina.     

The southernmost records of Anhingidae and a new basal species of Anatidae (Aves) from the lower–middle Miocene of Patagonia,Argentina

New bird fossils from the Santa Cruz Formation (lower–middle Miocene), Santa Cruz Province, Patagonia, Argentina, are described. They represent an indeterminate species of the extinct anhingid Macranhinga and a new genus and species of basal Anatidae Ankonetta larriestrai. The record of the giant darter Macranhinga constitutes the southernmost record for the family, and expands the known stratigraphic range of the genus, previously restricted to the upper Miocene. Based on an analysis of the fossil anhingid record from South America, we hypothesize that giant darters disappeared from South America in the early Pliocene due to climatic deterioration, regression of marine and freshwater environments, the arrival of placental carnivorous mammals, and also probably by competition with phalacrocoracid cormorants. The new anatid Ankonetta is based on an incomplete but informative tarsometatarsus, with superficial similarities to extant Dendrocygna. A brief overview of several fossil ducks from the Patagonian Cenozoic concludes that most pre-Pliocene examples belong to non-anatine taxa, indicating that plesiomorphic ducks were the dominant anseriforms in those times, a pattern also evident on other continents.     

Systematic status of the Miocene darter ‘Liptornis’ hesternus Ameghino, 1895 (Aves,Suliformes, Anhingidae) from Patagonia,Argentina

Diederle, J.M., 1.8.2015. Systematic status of the Miocene darter ‘Liptornis’ hesternus Ameghino, 1895 (Aves, Suliformes, Anhingidae) from Patagonia, Argentina. Alcheringa 39, 589–594. ISSN 0311-5518.

Liptornis hesternus was established by Ameghino in the late 1800s on the basis of a cervical vertebra (NHMUK-A599) from the Santa Cruz Formation (Santacrucian, South American Land Mammal Age, early Miocene, Burdigalian Stage) of Patagonia, Argentina. Although taxonomic attributions were controversial, the specimen is now confidently assigned to Anhingidae. Recently, however, L. hesternus was designated a nomen dubium because of its uninformative diagnostic characters and apparent loss of the holotype. Nevertheless, NHMUK-A599 has been relocated and is redescribed here prompting referral to Anhinga. A combination of traits are shared with the extant Anhinga anhinga and A. melanogaster, and the material is dimensionally compatible with A. anhinga. The estimated body size of NHMUK-A599 would have been larger than A. minuta but less than A. grandis, A. subvolans, A. fraileyi and A. walterbolesi. Finally, Anhinga hesterna is considered valid and represents the stratigraphically oldest occurrence of the genus in South America and the southernmost yet recorded.

Juan M. Diederle [juandiederle@cicyttp.org.ar], Laboratorio de Paleontología de Vertebrados, Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción (CICYTTP-CONICET), Materi y España, E3105BWA Diamante, Entre Ríos, Argentina.     

The northernmost South American fossil record of Boa constrictor (Boidae,Boinae) from the Plio–Pleistocene of El Breal de Orocual (Venezuela)

Onary-Alves, S.Y., Hsiou, A.S. & Rincón, A.D., July 2016. The northernmost South American fossil record of Boa constrictor (Boidae, Boinae) from the Plio–Pleistocene of El Breal de Orocual (Venezuela). Alcheringa 41, xxx–xxx. ISSN 0311-5518.

Boa constrictor is an extant boid widely distributed through the neotropical region, from the north of Central America to central Argentina. The fossil record of the species includes examples from several localities across the Americas that extend beyond the current distribution of the species. Here we report the first Plio–Pleistocene fossils of Boa from Monagas state, Venezuela. The material comes from El Breal de Orocual (Maturín municipality), which is an inactive tar seep deposit emplaced within the Mesa Formation. The specimens consist of two isolated anterior trunk vertebrae, an articulated sequence of six mid-trunk vertebrae and two posterior trunk vertebrae. The vertebrae are attributed to B. constrictor based on the following features: robust and high vertebrae; thick zygosphene with a notched or concave anterior edge; presence of a paracotylar, subcentral and lateral foramina; marked parasagittal ridges; epizygapophyseal process evident on the dorsal surface of the postzygapophyseal articular facets and high blade-like neural spine. The presence of B. constrictor in northern of Venezuela indicates a palaeoenvironment probably like savanna crossed by rivers with riparian forests, and suggests the predominance of a mesothermal climate with a moderate rainfall.

Silvio Y. Onary-Alves [silvioyuji@gmail.com], Programa de Pós-graduação em Biologia Comparada, Faculdade de Filosofia, Ciências e Letras, Universidade de São Paulo (USP), Av. Bandeirantes 3900, CEP 14040901, Ribeirão Preto, São Paulo, Brazil; Annie S. Hsiou [anniehsiou@ffclrp.usp.br], Laboratório de Paleontologia, Faculdade de Filosofia, Ciências e Letras, Departamento de Biologia, Universidade de São Paulo (USP), Av. Bandeirantes 3900, CEP 14040901, Ribeirão Preto, São Paulo, Brazil; Ascanio D. Rincón [paleosur1974@gmail.com], Laboratorio de Paleontología, Centro de Ecología, Instituto Venezolano de Investigaciones Científicas (IVIC), Carretera Panamericana Km 11, 1020-A Caracas, Venezuela.     

Archaeometrical characterization of pigments and paintings on Pre-Hispanic pottery from the regions of Fiambalá and Chaschuil (Catamarca,Argentina)*

The results of an analysis of pigments used in slips and designs deployed in ceramic assemblages recovered from archaeological sites located in different environments, expressing the socio-historical process developed in the regions of Fiambalá and Chaschuil (Catamarca, Argentina) during the last 1500 years are presented. The sample, formed by fragments of different ceramic styles and natural pigments, was analysed via Raman spectroscopy and X-ray diffraction. Results indicate the continuity in use of certain pigments (mainly hematite for red hues and Mn oxides in combination with magnetite for black paints) within the different socio-political organizations that inhabited the region from the first to the 14th centuries ce , in spite of the diverse shades of colour, which suggests an intentional search linked with their cultural conventions. For the Inca Period, this scenery of continuities in minerals employed for reds and blacks is complemented by the use of new compounds (Ti oxide, apatite and gypsum) in order to generate the ‘cream’ tones applied as slips, all of which have not been identified for previous moments.     

Holothuroidea: new records from the Lower Cretaceous of the Agrio Formation,Neuquén Basin,Argentina. An integrated study with foraminifers and calcareous nannofossils

CaramÉs, A., Martinez, M., Concheyro, A., RemÍrez, M. & Adamonis, S., 6 August 2019 2019. Holothuroidea: new records from the Lower Cretaceous of the Agrio Formation, Neuquén Basin, Argentina. An integrated study with foraminifers and calcareous nannofossils. Alcheringa XX, xx–xx. ISSN 0311-5518

New records of holothurian ossicles (Echinodermata) from the Lower Cretaceous Agrio Formation, Mendoza Group, in the northern Neuquén Basin, west-central Argentina, represent, excepting some general mention of ossicles, the first collection from the Lower Cretaceous of South America. The discovery is one of the few worldwide records of holothurian remains from this age. The analysed skeletal elements are associated with other microfauna and nannoflora retrieved from washed residues of claystones and marlstones of the lower strata of the Pilmatué Member, in Área 3000 and Puerta Curaco sections. The calcareous microfossil assemblage is composed almost exclusively of the foraminifera Epistomina loncochensis, suggesting quiet marine environments and low levels of dissolved oxygen in the bottom/water interface. A late Valanginian age is confirmed by the nannofossil assemblage found together with the holothurian ossicles. Analysis of ossicle shapes allows their attribution to molpadiids (Molpadida: Molpadiidae): one two-armed racquet-like single ossicle that remains as an indeterminate molpadiid and a new genus and species proposed for the abundant cross-shaped and star-shaped ossicles. The latter, owing to the presence of four holes and the lack of a spire or some elevation projecting well out from surface in the centre of the plates, resemble two known species of the genus Cruxopadia Reich, but they differ in their arm morphology.

Andrea Caramés [carames@gl.fcen.uba.ar], IDEAN—Instituto de Estudios Geológicos Andinos ‘Don Pablo Groeber’, CONICET, Ciudad Universitaria Pabellón II, Intendente Güiraldes 2160-C1428EHA Buenos Aires, Argentina; Mariano Martinez [mmartinez@macn.gov.ar], Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’, CONICET, A. Gallardo 470-C1405DJR Buenos Aires, Argentina; Andrea Concheyro [andrea@gl.fcen.uba.ar], IDEAN—Instituto de Estudios Geológicos Andinos ‘Don Pablo Groeber’, CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria Pabellón II, Intendente Güiraldes 2160-C1428EHA Buenos Aires, Argentina, and Instituto Antártico Argentino, Argentina; Mariano Remírez [mremirez@cig.museo.unlp.edu.ar], CIG—Centro de Investigaciones Geológicas, CONICET, Universidad Nacional de La Plata, Diagonal 113 N° 275-B1904DPK, La Plata, Argentina; Susana Adamonis [suad@gl.fcen.uba.ar], Departamento de Ciencias Geológicas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, IDEAN. Ciudad Universitaria Pabellón II, Intendente Güiraldes 2160-C1428EHA Buenos Aires, Argentina.     

The Challenge to ‘Informal’ Empire: Argentina,Chile and British Policy-Makers in the Immediate Aftermath of the First World War

From the late nineteenth century, both Argentina and Chile were integral parts of Britain’s ‘informal’ empire in Latin America. It has been suggested by historians that this ‘informal empire’ came to an end around the mid-twentieth century. By analysing contemporary sources from within the British government and the findings of later economic historians, it is the purpose of this article to contest this viewpoint. It will instead argue that the end of ‘informal’ empire in these countries was a direct consequence of the First World War, and that the decline in British influence in the region was registered by British policy-makers much earlier than has previously been argued.     

Pliocene Mollusca (Bivalvia,Gastropoda) from the Sørsdal Formation,Marine Plain,Vestfold Hills,East Antarctica: taxonomy and implications for Antarctic Pliocene palaeoenvironments

Quilty, P.G., Darragh, T.A., Gallagher, S.J. & Harding, L.A. July 2016. Pliocene Mollusca (Bivalvia, Gastropoda) from the Sørsdal Formation, Marine Plain, Vestfold Hills, East Antarctica: taxonomy and implications for Antarctic Pliocene palaeoenvironments. Alcheringa 40, XXX–XXX. ISSN 0311-5518.

Pliocene shallow-water marine sediments at Marine Plain (centred on 68°37.7?S; 78°07.8?E) and covering approximately 10 km² in the Vestfold Hills, East Antarctica, have yielded six species of gastropods, and 11 species of bivalves from two beds within the Sørsdal Formation. Most of the material is close to in situ but some specimens have been disturbed from their life position; there is no evidence of significant transport. The gastropods include Nacella concinna (Strebel, 1908), Falsimargarita parvispira Quilty, Darragh, Gallagher & Harding sp. nov., indeterminate species of trochids and naticids, Chlanidota (Chlanidota) sp. cf. C. signeyana Powell, 1951, and two species of Trophon/Trophonella. Bivalves include Ennucula sp. aff. E. grayi (d’Orbigny, 1846), Aequiyoldia defossata Quilty, Darragh, Gallagher & Harding, sp. nov., ‘Pectunculina’ sp., Lissarca sp., Austrochlamys anderssoni (Hennig, 1911), Ruthipecten campestris Quilty, Darragh, Gallagher & Harding sp. nov., Adamussium necopinatum Quilty, Darragh, Gallagher & Harding sp. nov., Limatula (Antarctolima) sp. cf. L. hodgsoni (Smith, 1907), Cyclocardia magna Quilty, Darragh, Gallagher & Harding sp. nov., ?Hiatella sp. cf. H. arctica (Linnaeus, 1767) and Laternula elliptica (King, 1832). Preservation varies considerably owing to recrystallization, dissolution or distortion through compaction, so several species are left in open nomenclature. Oxygen isotope data indicate that water temperature was 4–7.5°C at the time of shell growth. Many species or species groups are now extinct or have migrated away from the Antarctic to the sub-Antarctic region. An Antarctic mollusc fauna has been characteristic of the region for much of the Cenozoic.

Patrick G. Quilty [p.quilty@utas.edu.au], Discipline of Earth Sciences, University of Tasmania, Private Bag 79, Hobart, Tasmania 7001, Australia; Thomas A. Darragh [tdarragh@museum.vic.gov.au], Museum Victoria, GPO Box 666 Melbourne, Victoria 3000, Australia; Stephen J. Gallagher [sjgall@unimelb.edu.au], School of Earth Sciences, The University of Melbourne, Victoria 3010, Australia; Lucy A. Harding [harding.lucy.a@edumail.vic.gov.au], School of Earth Sciences, The University of Melbourne, Victoria 3010, Australia.     

Not all were Spears and Facones: Firearms from Otamendi Fortlet (1858–1869), Buenos Aires Province,Argentina

Abstract

Otamendi fortlet is located in Buenos Aires province (Argentina) and was occupied from 1858 to 1869. Previous archaeological research has yielded large quantities of artefacts from the site; the present study focuses on firearms and related material. The aim of this project is to identify and characterize the firearms to establish their function, place of origin and chronology. They are compared to the archaeological record of Minaña fortlet to understand the diversity of armament technology in border military settlements of the South Frontier against indigenous people during the second half of the nineteenth century in Argentina.     

The Colonial (Dis)order and the (Im)possibility of Redemption: Jeong,Abolition, and Living from the “End of the World”

This article develops the oppositional edge of postcolonial theologies by way of Frantz Fanon’s anti-colonial desire for the “end of the world.” It connects W. Anne Joh’s elaboration of jeong – the living in excess of (neo)colonial violence – to Dietrich Bonhoeffer’s anti-fascist critique of the godlike desires of European humanism (the sicut deus). The overall aim of the article is to clarify and assess what is at stake in a project of eschatological decolonialism. What might it mean to think theologically about salvation as abolition? And what might it look like to live from the “end of the world?”     

The Cold War,the developing world,and the creation of the International Atomic Energy Agency (IAEA), 1953–1957

This article argues that the creation of the IAEA (1953–1957) was shaped by the overlapping dynamics of superpower relations, decolonisation, and the growing influence of the ‘global South’ in the United Nations. During the four years of multilateral and international negotiations, many of the developing countries argued that the new organisation should not exacerbate global inequalities, practice discrimination, or institutionalise ‘atomic colonialism’. While American-Soviet understanding during these negotiations was at times strikingly good, the uranium-producing states and the future recipients of IAEA technical assistance often faced each other as rival blocs. The article is based on multi-archival research at the IAEA and the UN, as well as at the National Archives of the United States, the United Kingdom, and South Africa.     

Goodbye to all that (again)? The Fischer thesis,the new revisionism and the meaning of the First World War

What is the truth about the nature of the First World War and why have historians been unable to agree on its origins? The interpretation that no one country was to blame prevailed until the 1960s when a bitter international controversy, sparked by the work of the Hamburg historian Fritz Fischer, arrived at the consensus that the Great War had been a ‘bid for world power’ by imperial Germany and therefore a conflict in which Britain had necessarily and justly engaged. But in this centennial year Fischer's conclusions have in turn been challenged by historians claiming that Europe's leaders all ‘sleepwalked’ into the catastrophe. This article, the text of the Martin Wight Memorial Lecture held at the University of Sussex in November 2014, explores the archival discoveries which underpinned the Fischer thesis of the 1960s and subsequent research, and asks with what justification such evidence is now being set aside by the new revisionism.     

Howchinia Cushman, 1927 (Foraminifera) from the Mississippian Bei’an Formation and its distribution in South China

Shen, Y. & Wang, X.L., July 2016. Howchinia Cushman, 1927 (Foraminifera) from the Mississippian Bei’an Formation and its distribution in South China. Alcheringa 40, xxx–xxx. ISSN 0311-5518.

Howchinia Cushman is a useful biostratigraphic marker for Mississippian rocks. In South China, Howchinia has been reported from four sections: the Bei’an, Baping, Naqing and Yashui sections; with high species diversity in the Bei’an section. Ten species from the Mississippian Bei’an Formation in the Bei’an section are described in this paper: Howchinia bradyana, H. beleutensis, H. gibba, H. plana, H. convexa, H. subconica, H. subplana, Howchinia sp. A, Howchinia sp. B. and Howchinia beianensis sp. nov. Howchinia ranges from late Visean to early Bashkirian in South China. Howchinia species inhabited both shallow-water and relatively deep-water environments.

Yang Shen [shenybj@126.com] and Xun-Lian Wang [wxl@cugb.edu.cn], State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, 29 Xueyuan Road, Beijing 100083, PR China.     

Rhexoxylon cortaderitaense (Menéndez) comb. nov., a species of permineralized stems newly assigned to the Corystospermaceae,from the Triassic of Argentina

Bodnar, J., June, 2008. Rhexoxylon cortaderitaense (Menéndez) comb. nov., a species of permineralized stems newly assigned to the Corystospermaceae, from the Triassic of Argentina. Alcheringa 32, 171–190. ISSN 0311-5518.

Anatomically preserved stems of Late Triassic corystosperms from the upper Cortaderita Formation in San Juan province, Argentina are described and assigned to Rhexoxylon cortaderitaense (Menéndez) comb. nov. These specimens were originally attributed to conifers, a group not closely related to corystosperms. The silicified axes preserve features of the cortex, pith, and secondary vascular system. Like all Rhexoxylon species, these axes have two discontinuous cambial rings that develop centrifugal secondary xylem (normal secondary xylem) and centripetal secondary xylem (inverted secondary xylem). Both types of xylem are separated by a band of parenchymatous tissue developed by a remnant cambium. The centrifugal xylem is divided by parenchymatous rays following differential cambial activity. The secondary xylem is pycnoxylic with uniseriate rays; tracheids have mainly biseriate and alternate bordered pits on radial and tangential walls, and one simple oval pit in cross-fields. The distinctive feature of R. cortaderitaense is the conspicuous amount of centripetal secondary vascular tissues not forming perimedullar bundles, this being interpreted as an apomorphic trait. This interpretation of the character modifies previous hypothesized phylogenetic relationships of corystosperm wood taxa.     

Preservation assessment of Miocene–Pliocene tooth enamel from Tugen Hills (Kenyan Rift Valley) through FTIR,chemical and stable-isotope analyses

We investigated fossil tooth enamel of mammals and crocodiles from two Mio-Pliocene East-African formations (Lukeino and Mabaget Fms) using infrared spectroscopy and chemical and stable-isotope analyses. Infrared spectra indicate that the fossil enamel contains biological apatite (bioapatite), without significant secondary carbonate contaminations. Several empirical infrared indexes were used to analyze the crystal–chemical characteristics of enamel. Fossil enamel has less organic matter, water and structural carbonate of apatite than modern enamel with which it was compared. Fossil apatite has a better crystallinity than bioapatite. The calcium/phosphorus mass ratio and the fluorine content of fossil apatite show intermediate values between bioapatite and geological fluorapatite. The samples also display significant crystal-chemical variations, depending on the vertebrate group (mammals vs. reptiles) and the taphonomic context (Lukeino Fm vs. Mabaget Fm). In spite of these changes, no relationship was observed between the chemical contents (carbonate and fluorine) and the stable-isotope ratios of carbonate (δ¹³C and δ¹⁸O) in fossil enamel. Preservation of the palaeoenvironmental signals is strongly supported by the fact that the stable-isotope composition of the three investigated fossil mammalian taxa (deinotheres, equids and hippos) is consistent with their ecological features. For instance, typical C₃- and C₄-plant isotope compositions are reflected in the deinotheres and equids, respectively, and amphibious hippos display lower δ¹⁸O values than terrestrial herbivores, as expected.