A Late Cretaceous amber biota from central Myanmar

International audienceInsect faunas are extremely rare near the latest Cretaceous with a 24-million-year gap spanning from the early Campanian to the early Eocene. Here, we report a unique amber biota from the Upper Cretaceous (uppermost Campanian ~72.1 Ma) of Tilin, central Myan-mar. The chemical composition of Tilin amber suggests a tree source among conifers, indicating that gymnosperms were still abundant in the latest Campanian equatorial forests. Eight orders and 12 families of insects have been found in Tilin amber so far, making it the latest known diverse insect assemblage in the Mesozoic. The presence of ants of the extant sub-families Dolichoderinae and Ponerinae supports that tropical forests were the cradle for the diversification of crown-group ants, and suggests that the turnover from stem groups to crown groups had already begun at ~72.1 Ma. Tilin amber biota fills a critical insect faunal gap and provides a rare insight into the latest Campanian forest ecosystem

Biomacromolecules of Fossil Algae, Spores and Zooclasts from Selected Time Windows of Proterozoic to Mesozoic Age as Revealed by Pyrolysis-Gas Chromatography-Mass Spectrometry : A Biogeochemical Study

This study has revealed the molecular composition of extraordinarily well preserved palynomorphs (organic-walled microfossils) from selected time windows of Proterozoic to Mesozoic time. Sedimentary rock samples were collected from 11 localities: Hazro area (SE Turkey), Ruhr Basin (Germany), Weilerbach-Quierchied (Germany), Zwickau (Germany), Alstätte Embayment (German-Dutch border), Wülfrath (Germany), Gotland (Sweden), Oklahoma (USA), Virginia (USA), Rampura (India) and Tasmania (Australia). All samples are of low thermal maturity (Rock Eval T$_{max}$ 418°C (R$_{c}$~0.40) - 444°C (R$_{c}$~0.75)), except sediments from Suket Shale (Rampura, India). Palynomorphs which are taxonomically well assigned by project collaborators have been handpicked from the total organic residues. For the present investigations, various types of palynomorphs, for example, $\textit{Tasmanites, Leiosphaeridia}$, chitinozoans, scolecodonts, various megaspores and $\textit{Chuaria circularis}$ have been selected. An approach combining microscopy, Micro-Fourier transform infrared (FTIR) spectroscopy and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) has been applied. $\textit{Tasmanites}$ (thick-walled) and $\textit{Leiosphaeridia}$ (thin-walled) are assigned to prasinophycean green algae. Although, $\textit{Tasmanites}$ and $\textit{Leiosphaeridia}$ are morphologically distinct, their overall chemical compositions are similar. The pyrolysates from both thick-walled and thin-walled prasinophytes are dominated by a series of $\textit{n}$-C$_{6-22}$ alkene/alkane doublets which are typical of pyrolysis products of algaenan, the microbiological resistant algal biopolymer. The pyrolysates of the $\textit{Tasmanites}$ from Tasmania (Upper Carboniferous/Lower Permian) show a normal tricyclic terpenoid product distribution, but no traces of tricyclic terpenoids have been detected from the pyrolysates of $\textit{Tasmanites}$ from Turkey (Dadas Formation, Upper Silurian/Lower Devonian) and USA (Arbuckle Mountains, Oklahoma, Upper Devonian/Lower Carboniferous and Chattanooga Shale, Upper Devonian, Virginia). However, the pyrolysates of $\textit{Leiosphaeridia}$ from Turkey show the presence of monounsaturated and diunsaturated tricyclic terpenes as well as monoaromatic tricyclic terpanes. Hence, the inherent source-biomarker relationship between the $\textit{Tasmanites}$ and tricyclic terpenoids does not always exist. Furthermore, tricyclic terpenoid pyrolysates of the $\textit{Leiosphaeridia}$ confirms that there are more than one biological source(s) of these biomarkers and they are not exclusively from or always diagnostic of $\textit{Tasmanites}$. $\textbf{Chitinozoans}$ represent a group of flask-like, marine, organic-walled microfossils with uncertain biological affinity. Biomacromolecules of Chitinozoa (Dadas Formation, Upper Silurian, SE Turkey) of present investigation consist of both aliphatic and aromatic moieties. Aromatic pyrolysis products predominate over aliphatic pyrolysis products. Alkylbenzenes, alkylnaphthalenes, alkylphenols and alkylphenanthrenes are the major aromatic compounds found in the pyrolysates of Chitinozoa. A series of $\textit{n}$-alkene/$\textit{n}$-alkane doublets in the pyrolysates represents the aliphatic moiety. Micro-FTIR data are consistent with the pyrolytic studies emphasizing that biomacromolecules of the Chitinozoa investigated in the present study consist of both aromatic and aliphatic components. No pyrolysis products diagnostic of chitin have been detected in the present study. It is unlikely that the original macromolecules of Chitinozoa before fossilization were made of chitin related compounds. Chitinozoans belong to a group of rare marine fossils that have a substantial amount of ‘lignin-like’ macromolecular matter. Both spectroscopic and pyrolytic investigations demonstrate that the sporopollenin of the fossil $\textbf{megaspores}$ (from Cretaceous and Pennsylvanian sediments, Germany) consists of both aliphatic [...

On the affinity of Chuaria circularis Walcott : a multidisciplinary study

In this study, we utilized biometric, structural engineering and micro-FTIR (Fourier Transform Infrared Spectroscopy) analyses to examine the possible biological affinity of Chuaria circularis Walcott, collected from the Mesoproterozoic Suket Shales of the Vindhyan Supergroup and the Neoproterozoic Halkal Shales of the Bhima Supergroup of peninsular India. On the basis of these studies, contrary to the present belief, we conclude that Chuaria circularis was most likely a cylindrical body of algal origi

On the affinity of Chuaria-Tawuia complex: a multidisciplinary study

In this study, biometric and structural engineering tool have been used to examine a possible relationship within Chuaria–Tawuia complex and micro-FTIR (Fourier Transform Infrared Spectroscopy) analyses to understand the biological affinity of Chuaria circularis Walcott, collected from the Mesoproterozoic Suket Shales of the Vindhyan Supergroup and the Neoproterozoic Halkal Shales of the Bhima Group of peninsular India. Biometric analyses of well preserved carbonized specimens show wide variation in morphology and uni-modal distribution. We believe and demonstrate to a reasonable extent that C. circularis most likely was a part of Tawuia-like cylindrical body of algal origin. Specimens with notch/cleft and overlapping preservation, mostly recorded in the size range of 3–5 mm, are of special interest. Five different models proposed earlier on the life cycle of C. circularis are discussed. A new model, termed as ‘Hybrid model’ based on present multidisciplinary study assessing cylindrical and spherical shapes suggesting variable cell wall strength and algal affinity is proposed. This model discusses and demonstrates varied geometrical morphologies assumed by Chuaria and Tawuia, and also shows the inter-relationship of Chuaria–Tawuia complex. Structural engineering tool (thin walled pressure vessel theory) was applied to investigate the implications of possible geometrical shapes (sphere and cylinder), membrane (cell wall) stresses and ambient pressure environment on morphologically similar C. circularis and Tawuia. The results suggest that membrane stresses developed on the structures similar to Chuaria–Tawuia complex were directly proportional to radius and inversely proportional to the thickness in both cases. In case of hollow cylindrical structure, the membrane stresses in circumferential direction (hoop stress) are twice of the longitudinal direction indicating that rupture or fragmentation in the body of Tawuia would have occurred due to hoop stress. It appears that notches and discontinuities seen in some of the specimens of Chuaria may be related to rupture suggesting their possible location in 3D Chuaria. The micro-FTIR spectra of C. circularis are characterized by both aliphatic and aromatic absorption bands. The aliphaticity is indicated by prominent alkyl group bands between 2800–3000 and 1300–1500 cm−1. The prominent absorption signals at 700–900 cm−1 (peaking at 875 and 860 cm−1) are due to aromatic CH out of plane deformation. A narrow, strong band is centred at 1540 cm−1 which could be COOH band. The presence of strong aliphatic bands in FTIR spectra suggests that the biogeopolymer of C. circularis is of aliphatic nature. The wall chemistry indicates the presence of ‘algaenan’—a biopolymer of algae

Molecular signatures of kerogens and bitumens from the Lower Devonian Rhynie chert: Insights into the botanical affinity of the earliest land plants

International audienceThe Lower Devonian Rhynie chert of Scotland is an iconic geological formation that preserves the earliest known terrestrial ecosystem. This assemblage contains key evidence of earliest lineages of land plants, e.g., protracheophytes and paratracheophytes (former Rhyniaceae), together with animals, fungi, algae, and bacteria (Edwards et al., 2017). The exquisite preservation of this early biota provides an ideal scenario to explore the basal evolution of the land biosphere.The Rhynie chert has been vastly studied from multiple viewpoints, however, the biomolecular composition, i.e., “molecular signature”, of the Rhynie flora, including the early detection of fossil lignin, remains clearly unresolved. Lignin biosynthesis has been considered as one of the crucial influences behind the survival and proliferation of land plants in terrestrial ecosystems. Here, we characterize the molecular fossils to help decipher the botanical affinities of the Rhynie flora.Kerogens were isolated by the standard HF/HCl extraction procedure, and bitumens were extracted from the kerogens using organic solvents. The bitumens were studied with GC-MS, and the kerogens were analysed using Py-GC-MS and Py-GC×GC–TOFMS in the presence of TMAH reagent. The bitumens are characterized mainly by some aliphatic compounds such as a series of n-alkanes, pristane, phytane, and a series of diterpanes in very low abundance, as well as a set of aromatic compounds such as naphthalene and methylnaphthalenes, phenanthrene and methylphenanthrenes and retene. The pyrolysates, obtained using Py-GC-MS are dominated by benzene and methyl benzenes, phenol and methylphenols, Polycyclic Aromatic Hydrocarbons (PAHs) like naphthalene and methylnaphthalenes, phenanthrene and methylphenanthrenes, anthracene and methylanthracene, fluoranthene, pyrene, etc. Series of fatty acid methyl esters (FAME) and of n-alkane/alkene doublets were also detected. The thermochemolysates acquired from Py-GC×GC–TOFMS include the same compounds; additional methoxybenzene derivatives, methoxy toluene, methoxy benzaldehydes, and benzoic acid methyl esters, generated by reaction with TMAH, were also identified. Phenols and methoxybenzenes in the pyrolysates and thermochemolysates originate from lignin, and this is the first time that lignin monomers are formally identified from Rhynie chert samples

Molecular characterization of fossil palynomorphs by transmission micro-FTIR spectroscopy: Implications for hydrocarbon source evaluation

Transmission micro-FTIR spectroscopy has been conducted to elucidate the macromolecular structure of well-preserved fossil palynomorphs including prasinophycean algae, megaspores, chitinozoans, and scolecodonts. Plant and arthropod cuticles which may be present in palynological residues have also been investigated. Important differences are noted among these palynomorph groups regarding the intensities of CHx, Cdouble bond; length as m-dashO and aromatic Cdouble bond; length as m-dashC absorptions. Tasmanites, Leiosphaeridia, and plant cuticles are characterized by stronger aliphatic CHx stretching (3000–2800 cm− 1), strong CH3 (1460–1450 cm− 1), and intense Cdouble bond; length as m-dashO group (1710–1700 cm− 1) absorptions. Aromatic Cdouble bond; length as m-dashC stretching (1610–1560 cm− 1) absorptions are less intense and aromatic CH out of plane (900–750 cm− 1) absorptions are absent. In contrast, chitinozoans, scolecodonts, and arthropod cuticles show intense aromatic Cdouble bond; length as m-dashC stretching (1620–1560 cm− 1) and aromatic CH out of plane (900–750 cm− 1) absorptions. Aliphatic CHx stretching (3000–2800 cm− 1) and Cdouble bond; length as m-dashO group (1710–1700 cm− 1) absorptions are less intense. Megaspores are characterized by stronger aliphatic CHx stretching (3000–2800 cm− 1), strong CH3 (1460–1450 cm− 1), and moderate aromatic Cdouble bond; length as m-dashC stretching (1610–1560 cm− 1) and Cdouble bond; length as m-dashO group (1710–1700 cm− 1) absorptions. The CH2/CH3 intensity ratio has been used to assess the relative chain length and degree of branching. The aliphatic components in Tasmanites, Leiosphaeridia, and plant cuticles are longest chained and least branched whereas those in chitinozoans, scolecodonts, and arthropod cuticles are shortest chained and most branched. Megaspores show intermediate CH2/CH3 ratio. The present study demonstrates that palynomorphs differ in functional group chemistry and this spectroscopic technique can be useful to assign biological affinity of enigmatic palynomorphs. Furthermore, micro-FTIR spectroscopy provides insights into the hydrocarbon generating potential of different fossil palynomorph groups

Foraminiferal biostratigraphy of lignite mines of Kutch India: Age of lignite fossil vertebrates

The lignite deposits of Kutch, India are stratigraphically referred to the Naredi Formation and considered to be Early Eocene in age. The biostratigraphy of the older mine at Panandhro and a newly opened mine at Matanomadh has constrained the upper age limit of lignite to the early Bartonian. Its lower age may extend to the late Lutetian. Temporally the formation of lignite corresponds to the warming event of the Middle Eocene and suggests a humid climate at the onset of the warming. The previous palynological studies have already suggested dominance of tropical angiospermic pollen. A diverse assemblage of fossil whales and other vertebrates, many of them supposedly the oldest representatives, were reported from Panandhro mine. These were initially assigned to the Early Eocene and later to the Lute‑ tian age. The present biostratigraphic study revises their age to the Early Bartonian

Foraminiferal biostratigraphy of lignite mines of Kutch India: Age of lignite fossil vertebrates

AbstractThe lignite deposits of Kutch, India are stratigraphically referred to the Naredi Formation and considered to be Early Eocene in age. The biostratigraphy of the older mine at Panandhro and a newly opened mine at Matanomadh has constrained the upper age limit of lignite to the early Bartonian. Its lower age may extend to the late Lutetian. Temporally the formation of lignite corresponds to the warming event of the Middle Eocene and suggests a humid climate at the onset of the warming. The previous palynological studies have already suggested dominance of tropical angiospermic pollen. A diverse assemblage of fossil whales and other vertebrates, many of them supposedly the oldest representatives, were reported from Panandhro mine. These were initially assigned to the Early Eocene and later to the Lute‑ tian age. The present biostratigraphic study revises their age to the Early Bartonian