Until recently, our understanding of the evolution of human growth and development derived from studies of fossil juveniles that employed extant populations for both age determination and comparison. ...This circular approach has led to considerable debate about the human-like and ape-like affinities of fossil hominins. Teeth are invaluable for understanding maturation as age at death can be directly assessed from dental microstructure, and dental development has been shown to correlate with life history across primates broadly. We employ non-destructive synchrotron imaging to characterize incremental development, molar emergence, and age at death in more than 20 Australopithecus anamensis, Australopithecus africanus, Paranthropus robustus and South African early Homo juveniles. Long-period line periodicities range from at least 6-12 days (possibly 5-13 days), and do not support the hypothesis that australopiths have lower mean values than extant or fossil Homo. Crown formation times of australopith and early Homo postcanine teeth fall below or at the low end of extant human values; Paranthropus robustus dentitions have the shortest formation times. Pliocene and early Pleistocene hominins show remarkable variation, and previous reports of age at death that employ a narrow range of estimated long-period line periodicities, cuspal enamel thicknesses, or initiation ages are likely to be in error. New chronological ages for SK 62 and StW 151 are several months younger than previous histological estimates, while Sts 24 is more than one year older. Extant human standards overestimate age at death in hominins predating Homo sapiens, and should not be applied to other fossil taxa. We urge caution when inferring life history as aspects of dental development in Pliocene and early Pleistocene fossils are distinct from modern humans and African apes, and recent work has challenged the predictive power of primate-wide associations between hominoid first molar emergence and certain life history variables.
Humans have an unusual life history, with an early weaning age, long childhood, late first reproduction, short interbirth intervals, and long lifespan. In contrast, great apes wean later, reproduce ...earlier, and have longer intervals between births. Despite 80 y of speculation, the origins of these developmental patterns in Homo sapiens remain unknown. Because they record daily growth during formation, teeth provide important insights, revealing that australopithecines and early Homo had more rapid ontogenies than recent humans. Dental development in later Homo species has been intensely debated, most notably the issue of whether Neanderthals and H. sapiens differ. Here we apply synchrotron virtual histology to a geographically and temporally diverse sample of Middle Paleolithic juveniles, including Neanderthals, to assess tooth formation and calculate age at death from dental microstructure. We find that most Neanderthal tooth crowns grew more rapidly than modern human teeth, resulting in significantly faster dental maturation. In contrast, Middle Paleolithic H. sapiens juveniles show greater similarity to recent humans. These findings are consistent with recent cranial and molecular evidence for subtle developmental differences between Neanderthals and H. sapiens. When compared with earlier hominin taxa, both Neanderthals and H. sapiens have extended the duration of dental development. This period of dental immaturity is particularly prolonged in modern humans.
The Cherves-de-Cognac site (Charente, France) has yielded a diverse continental microvertebrate fauna of Berriasian (earliest Cretaceous) age. Dinosaur remains are rare, but include three teeth that ...are referrable to an indeterminate sauropod, which might represent either a titanosauriform, a non-titanosauriform macronarian or a non-neosauropod. The small size of these teeth (with a maximum length of 3 mm, as preserved) and the almost complete absence of emanel wrinkling suggests that they pertained to embryonic or hatchling individuals. The Cherves-de-Cognac sauropod represents a rare occurrence of sauropod embryos/ hatchlings, a new sauropod record from the poorly-known terrestrial Berriasian and another possible instance of the persistence of non-diplodocoid, non-titanosauriform sauropods into the Cretaceous.
The Late Jurassic Archaeopterygidae, comprising the iconic genus Archaeopteryx, is altogether among the earliest, basalmost and best-known Mesozoic avian taxa. The geographic distribution of ...Archaeopteryx is hitherto restricted to a limited region of southern Germany, probably due to preservation biases. Here we describe a tooth sorted among the more than 35,000 isolated teeth found by sieving sediments from the Cherves-de-Cognac locality (western France, Lower Cretaceous). This tooth crown is morphologically similar to teeth of the German specimens of Archaeopteryx (sensu lato), despite minor differences. The Cherves-de-Cognac tooth differs much more importantly from all other known taxa. It shares with different specimens of Archaeopteryx the general tooth size, recurved shape affecting apical third of crown, thin apical-mesial carina, constriction at base of crown giving distinctive S shape of distal edge in profile, absence of other ornamentation or serration, and shape of crown section. Incidentally, former assignments of teeth from the Upper Jurassic of Guimarota (Portugal) to cf. Archaeopteryx are unwarranted, as those teeth markedly differ from the Archaeopterygidae in several crucial features. We assign the new tooth to the family Archaeopterygidae, the earliest European birds, making it the first member of the family in Europe outside Germany, and extending its temporal occurrence to the early Cretaceous.
•A tooth from the Lower Cretaceous of France is assigned to the Archaeopterygidae.•It is the only record for the family outside southern Germany.•It also extends the record younger than the late Jurassic.•Purported teeth from Portugal actually do not belong to the Archaeopterygidae.
New discoveries on the ichnological site known as “the Pterosaur Beach of Crayssac” (lower Tithonian, Upper Jurassic; south-western France) answer the question of terrestrial capabilities of ...non-pterodactyloid pterosaurs. If the terrestrial type of locomotion of pterodactyloid pterosaurs has been solved from ichnological evidence for more than twenty years, no tracks and trackways referable to non-pterodactyloid pterosaurs have ever been described. Thus, the debate on terrestrial capabilities of these non-pterodactyloids was based on morpho-functional studies, with the main conclusion that those pterosaurs were arboreal dwellers and bad walkers. Six trackways referable to three non-pterodactyloid new ichnotaxa, maybe closely related to Rhamphorhynchidae, are described in this work. Their study leads to the conclusion that grounded non-pterodatyloids, at least during the Late Jurassic, were quadrupedal with digitigrade manus and plantigrade to digitigrade pes. They were clearly good walkers, even if hindlimbs are supposed to be hampered by the uropatagium, what could have constrained the terrestrial agility of these animals. Thus, from ichnological evidence and contrary to the current hypotheses, non-pterodactyloid pterosaurs seem to have been good walkers even though their trackways are very rare or unidentified to date. This rarity could be due to behaviour rather than to functional capacities, many non-pterodactyloids being considered both littoral fishers and arboreal or cliff dwellers. However, the concept of non-pterodactyloid “good climbers and bad walkers” has to be modified to “good climbers and rare walkers”, unless many non-pterodactyloid ichnites have yet to be discovered.
The fossil record of middle and late Miocene Eurasian hominoids has expanded considerably over the past few decades, particularly with the recovery of numerous isolated teeth and jaws. Scholars have ...turned to assessments of internal tooth structure and growth to make sense of the evolutionary radiations of these primates as well as their affinities to the living great apes (hominids). Here we characterize full-dentition enamel thickness and dental development in several juvenile Rudapithecus hungaricus individuals using multiple imaging modalities. Relative enamel thickness (RET) values for the anterior teeth and premolars of Rudapithecus are broadly akin to those of gorillas and chimpanzees and are thinner than those of orangutans. First molar RET values are most similar to chimpanzees, while posterior molar values are closer to thicker-enameled orangutans. When compared to Miocene hominoids, Rudapithecus shows an intermediate molar RET condition that is especially similar to other dryopithecines. Long-period line periodicity values are comparable to African apes and most Miocene hominoids, and lower than living and fossil orangutans. The mean cuspal daily secretion rate is similar to that of several other Miocene hominoids but is greater than extant great apes. Cusp-specific molar crown formation times generally exceed those of chimpanzees, are lower than those of orangutans, and are broadly like those of other Miocene apes. While Rudapithecus appears to have a somewhat unique pattern of enamel thickness and dental development relative to individual great ape genera, these structural and developmental features are consistent with its designation as a hominid.
Until recently, our understanding of the evolution of human growth and development derived from studies of fossil juveniles that employed extant populations for both age determination and comparison. ...This circular approach has led to considerable debate about the humanlike and ape-like affinities of fossil hominins. Teeth are invaluable for understanding maturation as age at death can be directly assessed from dental microstructure, and dental development has been shown to correlate with life history across primates broadly. We employ non-destructive synchrotron imaging to characterize incremental development, molar emergence, and age at death in more than 20 Australopithecus anamensis, Australopithecus africanus, Paranthropus robustus and South African early Homo juveniles. Long-period line periodicities range from at least 6-12 days (possibly 5-13 days), and do not support the hypothesis that australopiths have lower mean values than extant or fossil Homo. Crown formation times of australopith and early Homo postcanine teeth fall below or at the low end of extant human values; Paranthropus robustus dentitions have the shortest formation times. Pliocene and early Pleistocene hominins show remarkable variation, and previous reports of age at death that employ a narrow range of estimated long-period line periodicities, cuspal enamel thicknesses, or initiation ages are likely to be in error. New chronological ages for SK 62 and StW 151 are several months younger than previous histological estimates, while Sts 24 is more than one year older. Extant human standards overestimate age at death in hominins predating Homo sapiens, and should not be applied to other fossil taxa. We urge caution when inferring life history as aspects of dental development in Pliocene and early Pleistocene fossils are distinct from modern humans and African apes, and recent work has challenged the predictive power of primate-wide associations between hominoid first molar emergence and certain life history variables
The spotty nature of the terrestrial fossil record for the Mesozoic hinders a more complete understanding of dinosaur diversity. For stegosaurs (Ornithischia), the plated dinosaurs, only a few and ...fragmentary remains are reported from the Early Cretaceous of Europe. A recent revision concluded that only a partial vertebra of the
nomen dubium
Craterosaurus
(?Aptian, England) could be considered as stegosaurian. Here we report on a stegosaur tooth from the Early Cretaceous (Berriasian) Purbeckian deposits of Cherves-de-Cognac (Charente), southwestern France. This tiny tooth was examined in detail using microtomography. Comparisons being limited by the rarity of stegosaur tooth rows material (e.g., from the skull of the holotype of
Stegosaurus stenops
) and dental material, notably from Europe, we observed new material of cf.
Stegosaurus armatus
and
Hesperosaurus mjosi
from the Upper Jurassic Morrison Formation of Wyoming (USA). The tooth shows the most similarities to the Late Jurassic genera
Stegosaurus
and
Hesperosaurus
, but differs in having a distinctive downwardly arched (V-shaped) cingulum on the ?lingual face (maxillary tooth hypothesis). It is referred to as Stegosauria indeterminate, a medium-sized quadrupedal herbivore that inhabited an emerged land between the Armorican Massif and the Massif Central. This finding is the first evidence of a stegosaur from the Early Cretaceous of France and a welcome addition to the meagre European record of that time. In addition, it is the second stegosaurian tooth crown reported from Europe. The assemblage of ornithischians of Cherves-de-Cognac shares some similarities with that of the Early Cretaceous (Berriasian) of the Purbeck Limestone Group, southern England. The relative rarity of ornithischian osteological remains in both Purbeckian environments suggests that most of these dinosaurs were mainly inhabitants of inland terrestrial palaeoenvironments.
More than 1500 sauropod and theropod tracks have been discovered and excavated on the floor of a disused 3800m2 quarry, near the village of Loulle (French Jura). These levels correspond to a ...tidal-flat environment, from intertidal to supratidal zone, dated from the earliest Kimmeridgian (∼157M.a.). Eighteen sauropod trackways have been recognized, ranging from 3.8m to 51.5m in length. These trackways do not correspond to a unique herd passage, because trackways are diversely oriented, most of them are crossing others and prints are more or less deeply marked, depending of different stages of substratum competence. According to the trackway gauges, the three types (narrow-, medium and wide-gauge) are represented. Some trackways could be referred to the ichnogenus Brontopodus Farlow et al., 1989, and others to Parabrontopodus Lockley et al., 1994a. Based on footprint size, the body-sizes of these 18 sauropod trackways range from tiny (Pes Length<25cm) to large individuals (PL>75cm), showing a regular continuum of sizes. Several biometrical ratios classically used in sauropod ichnology appear to be closely related to size (e.g., the smallest individuals apparently moved faster than the largest; large individuals are all narrow-gauge while small individuals are all wide-gauge; large specimens are characterized by a high heteropody ratio when the smallest show a low heteropody ratio). Associated with these sauropod trackways, four theropod trackways have also been recorded. Three small to medium-sized theropod are referred to the ichnogenus Carmelopodus Lockley et al., 1998a, while a large individual (PL=77cm) is tentatively referred to Megalosauripus Lessertisseur, 1955.
The European record of continental vertebrates during the Earliest Cretaceous (Berriasian) is usually based on accumulation assemblages in littoral localities where faunas of various living ...environments and ecologies are mixed. A recently excavated site located in the southwest of France (Cherves-de-Cognac) corresponds to a hyper-saline lagoonal environment that has yielded a rich vertebrate fauna including brackish and freshwater fish, amphibious crocodilians and turtles, as well as terrestrial dinosaurs and mammals. While some of these taxa were most likely parautochthonous, others may have been transported from distant environments. In order to decipher the respective living environments of these vertebrates, and better understand the local climatic conditions, apatite phosphates of their teeth or bones have been analyzed for their oxygen isotope compositions. From these preliminary measurements, differences in phosphate δ18Op values observed between taxa most likely reflect differences in sources of ingested waters that are compatible with their assumed ecologies. Reconstructed δ18Ow values of environmental waters using PO4–water fractionation equations show that marine and brackish waters were submitted to enough evaporation for generating a hypersaline lagoon, as reflected by δ18Ow values ranging from −1.7‰ to +1.7‰, whereas the more inland freshwaters have δ18Ow values ranging from −4.1‰ to −1.8‰. The lowest water δ18Ow value of about −4‰ estimated from the δ18Op value of terrestrial mammals, which is assumed to be the composition of local meteoric waters, leads to estimate a mean air temperature of about 20±3°C at Cherves-de-Cognac during the Berriasian (30–35°N). Such temperatures are recorded today at similar latitudes; however, a weak equator to pole thermal gradient is evidenced by the latitudinal distribution of thermophilic taxa such as crocodilians.
•We have analyzed the δ18O values of vertebrate apatites from a Berriasian locality.•Variations in δ18O values between taxa reflect their different living environments.•Local paleo-environments are characterized by high evaporation rates.•Calculated air temperature of 20±3°C is similar to present day ones at low latitudes.•The results support the occurrence of a low latitudinal temperature gradient.
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