The diagenetic fate of collagen as revealed by analytical pyrolysis of fossil fish scales from deep time.

The mechanism of protein degradation has remained a topic of debate (specifically concerning their preservation in deep time), which has recently been invigorated due to multiple published reports of preservation ranging from Miocene to the Triassic that potentially challenge the convention that protein preservation beyond the Cenozoic is extremely uncommon or is expected to be absent altogether, and thus have attracted skepticism. In this paper, we analyze fossil fish scales from the Cretaceous, Jurassic, and Triassic using comprehensive pyrolysis gas chromatography coupled with time-of-flight mass spectrometry and compare the pyrolytic products so obtained with a well-preserved fish scale from Late Pliocene, in an attempt to better understand the effects of diagenesis on protein degradation at the molecular level through deep time. We find that the Pliocene fish scale displays a large number of N-bearing pyrolytic products, including abundant substituted cyclic 2,5-diketopiperazines (2,5-DKPs) which are diagnostic products of peptide and amino acid pyrolysis. We identify N-bearing compounds in the Mesozoic fish scales-however, among the 2,5-DKPs that were identified in the Pliocene scale, only diketodipyrrole (or cyclo (Pyr-Pyr)) is present in the Mesozoic scales. We discuss the implications of N-bearing pyrolytic products with emphasis on 2,5-DKPs in geological samples and conclude that the discrepancy in abundance and variety of N-bearing products between Pliocene and Mesozoic scales indicates that the protein component in the latter has been extensively diagenetically altered, while a suite of DKPs such as in the former would imply stronger evidence to indicate preservation of protein. We conclude that analytical pyrolysis is an effective tool for detecting preservation of intact proteins, as well as for providing insights into their degradation mechanisms, and can potentially be utilized to assign proteinaceous origin to a fossil sample of unknown affinity.

New Middle Miocene Ape (Primates: Hylobatidae) from Ramnagar, India fills major gaps in the hominoid fossil record.

The fossil record of 'lesser apes' (i.e. hylobatids = gibbons and siamangs) is virtually non-existent before the latest Miocene of East Asia. However, molecular data strongly and consistently suggest that hylobatids should be present by approximately 20 Ma; thus, there are large temporal, geographical, and morphological gaps between early fossil apes in Africa and the earliest fossil hylobatids in China. Here, we describe a new approximately 12.5-13.8 Ma fossil ape from the Lower Siwaliks of Ramnagar, India, that fills in these long-standing gaps with implications for hylobatid origins. This ape represents the first new hominoid species discovered at Ramnagar in nearly a century, the first new Siwalik ape taxon in more than 30 years, and likely extends the hylobatid fossil record by approximately 5 Myr, providing a minimum age for hylobatid dispersal coeval to that of great apes. The presence of crown hylobatid molar features in the new species indicates an adaptive shift to a more frugivorous diet during the Middle Miocene, consistent with other proposed adaptations to frugivory (e.g. uricase gene silencing) during this time period as well.

Porcupine gnaw marks on a Late Pliocene bone from the Upper Siwaliks exposed near Village Khetpurali (Haryana, India).

Bone accumulation by porcupines at archaeological sites is well known. However, in paleontological sites such a taphonomical occurrence is rather rare. We here report porcupine (Hystrix sp.) gnaw marks on an unidentified bone fragment, dated to ~2.6 Ma from the Upper Siwalik deposits exposed near Khetpurali (Haryana), India. The present gnaw marks are very distinct and are characterized by visible edges and grooves making clear broad and shallow furrows. The present find adds to our knowledge of Siwalik vertebrate taphonomy where most of the accumulations reported earlier were either fluvial or made by carnivores.

The first darter (Aves: Anhingidae) fossils from India (late Pliocene).

New fossils from the latest Pliocene portion of the Tatrot Formation exposed in the Siwalik Hills of northern India represent the first fossil record of a darter (Anhingidae) from India. The darter fossils possibly represent a new species, but the limited information on the fossil record of this group restricts their taxonomic allocation. The Pliocene darter has a deep pit on the distal face of metatarsal trochlea IV not reported in other anhingids, it has an open groove for the m. flexor perforatus et perforans digiti II tendon on the hypotarsus unlike New World anhingid taxa, and these darter specimens are the youngest of the handful of Neogene records of the group from Asia. These fossil specimens begin to fill in a significant geographic and temporal gap in the fossil record of this group that is largely known from other continents and other time periods. The presence of a darter and pelican (along with crabs, fish, turtles, and crocodilians) in the same fossil-bearing horizon strongly indicates the past presence of a substantial water body (large pond, lake, or river) in the interior of northern India in the foothills of the Himalayan Mountains.

New sivaladapid primate from Lower Siwalik deposits surrounding Ramnagar (Jammu and Kashmir State), India.

Over the past century, numerous vertebrate fossils collected near the town of Ramnagar, India, have proven to be important for understanding the evolution and biogeography of many mammalian groups. Primates from Ramnagar, though rare, include a number of hominoid specimens attributable to Sivapithecus, as well as a single published mandibular fragment preserving the P4-M1 of the Miocene adapoid Sivaladapis palaeindicus. Since 2010, we have renewed fossil prospecting in the Lower Siwalik deposits near Ramnagar in an attempt to better understand the evolution, biogeographic timing, and paleoclimatic context of mammalian radiations in Asia, with a particular focus on primates. Our explorations have resulted in the identification of new fossil localities, including the site of Sunetar. The age of Sunetar and the Ramnagar region, in general, is tentatively dated between 14 and 11 Ma. In 2014, a partial right mandible of a sivaladapid primate was recovered at Sunetar, preserving the corpus with P4 roots and worn M1-M3 dentition. Although sivaladapids are known by numerous specimens of two genera (Sivaladapis and Indraloris) at Lower Siwalik sites on the Potwar Plateau (Pakistan) and at the Middle Siwalik locality of Haritalyangar (India), this new specimen is just the second sivaladapid recovered from the Ramnagar region. Our analyses suggest that the new specimen is distinct from all other sivaladapids, and we therefore describe it as a new genus and species close to the base of the Sivaladapinae.

Crocodilian Nest in a Late Cretaceous Sauropod Hatchery from the Type Lameta Ghat Locality, Jabalpur, India.

The well-known Late Cretaceous Lameta Ghat locality (Jabalpur, India) provides a window of opportunity to study a large stable, near shore sandy beach, which was widely used by sauropod dinosaurs as a hatchery. In this paper, we revisit the eggs and eggshell fragments previously assigned to lizards from this locality and reassign them to crocodylomorphs. Several features point to a crocodilian affinity, including a subspherical to ellipsoidal shape, smooth, uneven external surface, discrete trapezoid shaped shell units with wide top and narrow base, basal knobs and wedge shaped crystallites showing typical inverted triangular extinction under crossed nicols. The crocodylomorph eggshell material presented in this paper adds to the skeletal data of these most probably Cretaceous-Eocene dryosaurid crocodiles.

A pelican tarsometatarsus (Aves: Pelecanidae) from the latest Pliocene Siwaliks of India.

We report a new fossil specimen of a pelican from the Tatrot Formation of the Siwalik Hills, India. It likely represents Pelecanus sivalensis Davies, 1880, the smaller of the two previously published species from the Siwalik Group stratigraphic sequence. This complete tarsometatarsus is the first fossil bone of a pelican collected in India for over 100 years. It is from the latest Pliocene (∼2.6 Ma), and is the youngest pelican fossil from the region. The new specimen exhibits a derived distoplantar 'slant' to the plantar margin of the medial crest of the hypotarsus, and a combination of features related to the morphology of the hypotarsus, the distal foramen, trochleae, and overall size that allow further differentiation from known tarsometatarsi of fossil and extant pelicans, including the three species of extant pelicans that occur in India (Pelecanus crispus, P. onocrotalus, and P. philippensis). It is of appropriate size for Pelecanus sivalensis, which to date has been known only by fragments of other skeletal elements of the wing, leg, and shoulder girdle. Thus, the observation that this tarsometatarsus is morphologically distinct from those of known pelicans provides further support for the distinctiveness of at least one extinct species of pelican from the Siwalik Group sediments. While the morphology of the tarsometatarsus allows for separation from other taxa known from tarsometatarsi, we found no clear shared derived states to place this taxon with any confidence in a phylogenetic context relative to any other pelican species, or even determine if it is part of the crown group of Pelecanidae. However, published molecular data are consistent with an origin of the crown clade prior to the Pleistocene, suggesting (along with one morphological character) the possibility that this species belongs to the Old World clade of pelican species.

Fossil mice and rats show isotopic evidence of niche partitioning and change in dental ecomorphology related to dietary shift in Late Miocene of Pakistan.

Stable carbon isotope analysis in tooth enamel is a well-established approach to infer C3 and C4 dietary composition in fossil mammals. The bulk of past work has been conducted on large herbivorous mammals. One important finding is that their dietary habits of fossil large mammals track the late Miocene ecological shift from C3 forest and woodland to C4 savannah. However, few studies on carbon isotopes of fossil small mammals exist due to limitations imposed by the size of rodent teeth, and the isotopic ecological and dietary behaviors of small mammals to climate change remain unknown. Here we evaluate the impact of ecological change on small mammals by fine-scale comparisons of carbon isotope ratios (δ(13)C) with dental morphology of murine rodents, spanning 13.8 to ∼2.0 Ma, across the C3 to C4 vegetation shift in the Miocene Siwalik sequence of Pakistan. We applied in-situ laser ablation GC-IRMS to lower first molars and measured two grazing indices on upper first molars. Murine rodents yield a distinct, but related, record of past ecological conditions from large herbivorous mammals, reflecting available foods in their much smaller home ranges. In general, larger murine species show more positive δ(13)C values and have higher grazing indices than smaller species inhabiting the same area at any given age. Two clades of murine rodents experienced different rates of morphological change. In the faster-evolving clade, the timing and trend of morphological innovations are closely tied to consumption of C4 diet during the vegetation shift. This study provides quantitative evidence of linkages among diet, niche partitioning, and dental morphology at a more detailed level than previously possible.

New geochronological, paleoclimatological, and archaeological data from the Narmada Valley hominin locality, central India.

The oldest known fossil hominin in southern Asia was recovered from Hathnora in the Narmada Basin, central India in the early 1980's. Its age and taxonomic affinities, however, have remained uncertain. Current estimates place its maximum age at >236ka, but not likely older than the early middle Pleistocene. The calvaria, however, could be considerably younger. We report recent fieldwork at Hathnora and associated Quaternary type-sections that has provided new geological and archaeological insights. The portion of the exposed 'Boulder Conglomerate' within the Surajkund Formation, which forms a relict terrace and has yielded the hominin fossils, contains reworked and stylistically mixed lithic artifacts and temporally mixed fauna. Three mammalian teeth stratigraphically associated with the hominin calvaria were dated by standard electron spin resonance (ESR). Assuming an early uranium uptake (EU) model for the teeth, two samples collected from the reworked surface deposit averaged 49+/-1ka (83+/-2ka, assuming linear uptake [LU]; 196+/-7ka assuming recent uptake [RU]). Another sample recovered from freshly exposed, crossbedded gravels averaged 93+/-5ka (EU), 162+/-8ka (LU) or 407+/-21ka (RU). While linear uptake models usually provide the most accurate ages for this environment and time range, the EU ages represent the minimum possible age for fossils in the deposit. Regardless, the fossils are clearly reworked and temporally mixed. Therefore, the current data constrains the minimum possible age for the calvaria to 49+/-1ka, although it could have been reworked and deposited into the Hathnora deposit any time after 160ka (given the LU uptake ages) or earlier (given the RU ages). At Hathnora, carbonaceous clay, bivalve shells, and a bovid tooth recovered from layers belonging to the overlying Baneta Formation have yielded (14)C ages of 35.66+/-2.54cal ky BP, 24.28+/-0.39cal ky BP, and 13.15+/-0.34ky BP, respectively. Additional surveys yielded numerous lithics and fossils on the surface and within the stratigraphic sequence. At the foot of the Vindhyan Hills 2km from the river, we recovered a typologically Early Acheulean assemblage comprised of asymmetrical bifaces, large cleavers with minimal working, trihedral picks, and flake tools in fresh condition. These tools may be the oldest Acheulean in the Narmada Valley. Several lithics recovered from the Dhansi Formation may represent the first unequivocal evidence for an early Pleistocene hominin presence in India. In situ invertebrate and vertebrate fossils, pollen, and spores indicate a warm, humid climate during the late middle Pleistocene. High uranium concentrations in the mammalian teeth indicate exposure to saline water, suggesting highly evaporative conditions in the past. Late Pleistocene sediment dated between 24.28+/-0.39cal ky BP and 13.15+/-340ky BP has yielded pollen and spores indicating cool, dry climatic conditions corresponding to Oxygen Isotope Stage 2 (OIS 2). An early Holocene palynological assemblage from the type locality at Baneta shows evidence for relatively dry conditions and a deciduous forest within the region. The Dhansi Formation provisionally replaces the Pilikarar Formation as the oldest Quaternary formation within the central Narmada Basin. The Baneta Formation, previously dated at 70ka to 128ka, correlates with the late Pleistocene and early Holocene. Our results highlight the need for further Quaternary geological and paleoanthropological research within the Narmada Basin, especially because dam construction threatens these deposits.