Millericrinids constitute an order of extinct articulate crinoids that range from the Middle Tria... more Millericrinids constitute an order of extinct articulate crinoids that range from the Middle Triassic to the Late Cretaceous. Based on partially articulated material comprising calyces, columns, and holdfasts, six species (one of them new) belonging to five different genera are described from the Late Jurassic of Spain for the first time. They include Angulocrinus tomaszi n. sp. from the Yatova Formation (middle-upper Oxfordian); and Millericrinus milleri, Liliocrinus polydactylus, Pomatocrinus hoferi, Pomatocrinus cf. mespiliformis, and Apiocrinites cf. parkinsoni from the Sot de Chera Formation (Kimmeridgian). A. tomaszi n. sp. lived in association with sponges and other invertebrates in relatively shallow, open platform areas, with variable depths near storm wave base. The assemblage from the Sot de Chera Formation is more diverse and preliminary taphonomic and sedimentological information suggest that these millericrinids lived in high-energy conditions from shore-face environme...
Stalked crinoids have generally been overlooked when considering trace fossil makers — largely be... more Stalked crinoids have generally been overlooked when considering trace fossil makers — largely because they were long considered fully sessile. However, observations both in the field and in laboratory experiments revealed that some members of the order Isocrinida use their arms to actively move along the bottom, dragging the stalk behind. This activity leaves distinct traces on the sediment surface. Here, we re-examined time-lapse movies made in 2017 and crawling traces produced by stalked crinoids (the isocrinine Metacrinus rotundus) in previously published neoichnological experiments using new 3D digitization techniques (laser scanning and photogrammetry) in order to provide a more detailed 3D morphology of these traces. These data reveal some previously unnoticed crawling behavior and features of the traces of M. rotundus. We also demonstrate that crinoid-bearing beds are sometimes associated with ichnofossils that can be potentially interpreted as crinoid crawling traces. These...
Proceedings of the Royal Society B: Biological Sciences
Over about 10 million years, the ancestors of whales transformed from herbivorous, deer-like, ter... more Over about 10 million years, the ancestors of whales transformed from herbivorous, deer-like, terrestrial mammals into carnivorous and fully aquatic cetaceans. Protocetids are Eocene whales that represent a unique semiaquatic stage in that dramatic evolutionary transformation. Here, we report on a new medium-sized protocetid, Phiomicetus anubis gen. et sp. nov., consisting of a partial skeleton from the middle Eocene (Lutetian) of the Fayum Depression in Egypt. The new species differs from other protocetids in having large, elongated temporal fossae, anteriorly placed pterygoids, elongated parietals, an unfused mandibular symphysis that terminates at the level of P 3 , and a relatively enlarged I 3 . Unique features of the skull and mandible suggest a capacity for more efficient oral mechanical processing than the typical protocetid condition, thereby allowing for a strong raptorial feeding style. Phylogenetic analysis nests Phiomicetus within the paraphyletic Protocetidae, as the m...
Crinoid and blastoid diversity and abundance peaked during the Late Devonian – early Mississippia... more Crinoid and blastoid diversity and abundance peaked during the Late Devonian – early Mississippian (Famennian – Viséan), an interval known as the Age of Crinoids. In North America, localities with maximum crinoid and blastoid diversity and abundance occurred in carbonate ramp and delta platform and slope deposits offshore from the Appalachian tectonic highlands. Living shallow-water crinoids reached maximum species diversity and abundance in more heterotrophic waters of the Indo-West Pacific Coral Triangle, Great Barrier Reef, and Caribbean crinoids are less diverse around coral-rich offshore islands and atolls in more oligotrophic waters. Ancient crinoids and blastoids were suspension feeders, limited by very narrow food grooves to capturing very small food particles. Blastoids in particular had food grooves <300 μm width, but crinoid food grooves were </= 100 μm to >1.25 mm, with most species <400 μm. Living crinoids, both unstalked and stalked, also have narrow food g...
Predation, an important driver of natural selection, is studied in the fossil record using quanti... more Predation, an important driver of natural selection, is studied in the fossil record using quantifiable traces like drill holes produced by gastropods and repair scars produced after durophagous attacks. Despite the abundance of such records in molluscan prey, predation records of micromolluscs (<5mm) remain largely unexplored. Using a Miocene assemblage of microgastropods from the Quilon Limestone, India, we established the predator-prey dynamics with the help of costbenefit analyses. The overall predation intensity, measured by drilling frequency (DF) and repair scare frequency (RF) is low (DF = 0.06, RF= 0.04). The predation intensity does not depend on the relative abundance of prey families suggesting a non-random prey selection regardless of the encounter frequency. Predation is selective as revealed by higher predation observed in prey of specific family identity, ornamentation, and body size. The smallest size class has the lowest DF and RF supporting a negative size refu...
Abundant, well-preserved archaic whale remains from Fayum deposits have facilitated our understan... more Abundant, well-preserved archaic whale remains from Fayum deposits have facilitated our understanding of the evolutionary transition of whales from the terrestrial to the marine realms (e.g., Gingerich and Smith, 1990; Gingerich et al., 1990; Gingerich and Uhen, 1996). However, the turtle remains from these formations have received significantly less attention and are still poorly understood. Among them are members of the subtribe Stereogenyina (Gaffney et al., 2011), previously referred to as the Shweboemysgroup turtles (Broin, 1988). Although similar to other podocnemidids in many respects, these pleurodires had an autapomorphic palatal structure that consisted of a
Apex predators live at the top of an ecological pyramid, preying on animals in the pyramid below ... more Apex predators live at the top of an ecological pyramid, preying on animals in the pyramid below and normally immune from predation themselves. Apex predators are often, but not always, the largest animals of their kind. The living killer whale Orcinus orca is an apex predator in modern world oceans. Here we focus on an earlier apex predator, the late Eocene archaeocete Basilosaurus isis from Wadi Al Hitan in Egypt, and show from stomach contents that it fed on smaller whales (juvenile Dorudon atrox) and large fishes (Pycnodus mokattamensis). Our observations, the first direct evidence of diet in Basilosaurus isis, confirm a predator-prey relationship of the two most frequently found fossil whales in Wadi Al-Hitan, B. isis and D. atrox. This extends our understanding of their paleoecology. Late Eocene Basilosaurus isis, late Miocene Livyatan melvillei, and modern Orcinus orca are three marine apex predators known from relatively short intervals of time. Little is known about whales as apex predators through much of the Cenozoic era, and whales as apex predators deserve more attention than they have received.
Understanding the timing and character of the expansion of Homo sapiens out of Africa is critical... more Understanding the timing and character of the expansion of Homo sapiens out of Africa is critical for inferring the colonization and admixture processes that underpin global population history. It has been argued that dispersal out of Africa had an early phase, particularly ~130-90 thousand years ago (ka), that reached only the East Mediterranean Levant, and a later phase, ~60-50 ka, that extended across the diverse environments of Eurasia to Sahul. However, recent findings from East Asia and Sahul challenge this model. Here we show that H. sapiens was in the Arabian Peninsula before 85 ka. We describe the Al Wusta-1 (AW-1) intermediate phalanx from the site of Al Wusta in the Nefud desert, Saudi Arabia. AW-1 is the oldest directly dated fossil of our species outside Africa and the Levant. The palaeoenvironmental context of Al Wusta demonstrates that H. sapiens using Middle Palaeolithic stone tools dispersed into Arabia during a phase of increased precipitation driven by orbital for...
Biological and physical factors govern the distribution of fossils, but it is not always clear wh... more Biological and physical factors govern the distribution of fossils, but it is not always clear which is more important. The preservation of late Eocene vertebrates at the UNESCO World Heritage site of Wadi Al-Hitan, Western Desert of Egypt, is controlled primarily by the physical processes responsible for sequence stratigraphic architecture on a siliciclastic shelf. Three types of stratigraphic surface, each characterized by a taxonomically and taphonomically distinct fossil assemblage, yield most of the known vertebrate fossils. Complete, partially articulated whale skeletons, primarily Basilosaurus isis, are abundant in offshore marine flooding surfaces (MFS) in the late transgressive systems tract (TST) of the first Priabonian sequence (TA4.1), where low net sedimentation rates and environmental averaging in offshore environments promoted the accumulation of carcasses on traceable stratigraphic surfaces. Complete, well-articulated whales, primarily Dorudon atrox, are more widely scattered on minor erosion surfaces in rapidly accumulating shoreface sediments of the overlying falling stage systems tract. Fragmented and abraded vertebrate remains are abundant and diverse in a discontinuous conglomerate that marks the first sequence boundary above the base of the Priabonian (Pr-2), which has not been previously recognized in Egypt, but which formed incised valleys with at least 45 m of total relief. Fossils in this variably thick lag conglomerate include skeletal elements reworked by rivers from underlying marine deposits and bones of terrestrial animals living in the fluvial environment. Marginal marine vertebrates, primarily dugongs, occur on shelly marine ravinement surfaces above Pr-2, in the early TST of the second Priabonian sequence. Most vertebrate remains in Wadi Al-Hitan occur in condensed stratigraphic intervals and taxonomic composition changes with sequence position, both important considerations in interpretation of paleobiological patterns. PALAIOS PETERS ET AL. FIGURE 2-Late Eocene-Oligocene timescale, inferred cycles in eustatic sea level, and third-order sequence boundaries (modified from Hardenbol et al., 1998). Studied interval shown (approximately) by hatched area. CN ϭ calcareous nannoplankton zones; PF ϭ planktonic foraminfera zones; SB ϭ sequence boundary.
ABSTRACT Remingtonocetids are semiaquatic archaeocete cetaceans known for their elongated narrow ... more ABSTRACT Remingtonocetids are semiaquatic archaeocete cetaceans known for their elongated narrow skulls, long necks, and robust pelves and hind limbs. The family currently includes five genera (Attockicetus, Remingtonocetus, Dalanistes, Andrewsiphius, and Kutchicetus), which are known principally from the middle-to-late Lutetian Domanda Formation of Pakistan and the late Lutetian Harudi Formation of India. Some specimens have been recovered from other formations; however, all previous occurrences have been restricted to the Lutetian of Indo-Pakistan. A new genus of remingtonocetid cetacean has been recovered from the late Lutetian Midawara Formation of Egypt. The specimen includes a left innominate with a complete ilium, ischium, and acetabulum; a nearly complete left femur; a four-vertebra sacrum; and partial lumbar and anterior caudal vertebrae. The long, broad ilium and near closure of the acetabular notch compare closely with the innominates of other remingtonocetids, though the ischium is much broader and flatter. The femur is generally similar in size and shape to known specimens of Remingtonocetus, but has a more vertically-oriented head and neck and a shaft with a more circular cross-section that lacks a conspicuous lateral keel. The sacrum is composed of four vertebrae, three of which are at least partially fused together as in other remingtonocetids, with very large dorsal sacral foramina. A well-preserved lumbar vertebra has curved zygapophyses, reniform epiphyses, and short transverse processes with only a modest degree of anterior or ventral inclination, comparing closely with lumbar vertebrae of Remingtonocetus. However, partial neural arches suggest that lumbar neural spines were inclined posteriorly rather than anteriorly. The new specimen increases the known taxonomic diversity of Remingtonocetidae, illustrates additional variation in the morphology and locomotor repertoire of the group, and provides the first evidence of the family in Africa.
Proceedings of the Royal Society B: Biological Sciences, 2012
Our understanding of locomotor evolution in anthropoid primates has been limited to those taxa fo... more Our understanding of locomotor evolution in anthropoid primates has been limited to those taxa for which good postcranial fossil material and appropriate modern analogues are available. We report the results of an analysis of semicircular canal size variation in 16 fossil anthropoid species dating from the Late Eocene to the Late Miocene, and use these data to reconstruct evolutionary changes in locomotor adaptations in anthropoid primates over the last 35 Ma. Phylogenetically informed regression analyses of semicircular canal size reveal three important aspects of anthropoid locomotor evolution: (i) the earliest anthropoid primates engaged in relatively slow locomotor behaviours, suggesting that this was the basal anthropoid pattern; (ii) platyrrhines from the Miocene of South America were relatively agile compared with earlier anthropoids; and (iii) while the last common ancestor of cercopithecoids and hominoids likely was relatively slow like earlier stem catarrhines, the results...
It is widely understood that Hominoidea (apes and humans) and Cercopithecoidea (Old World monkeys... more It is widely understood that Hominoidea (apes and humans) and Cercopithecoidea (Old World monkeys) have a common ancestry as Catarrhini deeply rooted in Afro-Arabia 1-4. The oldest stem Catarrhini in the fossil record are Propliopithecoidea, known from the late Eocene to early Oligocene epochs (roughly 35-30 Myr ago) of Egypt, Oman and possibly Angola 5-10. Genome-based estimates for divergence of hominoids and cercopithecoids range into the early Oligocene 11 ; however, the mid-to-late Oligocene interval from 30 to 23 Myr ago has yielded little fossil evidence documenting the morphology of the last common ancestor of hominoids and cercopithecoids, the timing of their divergence, or the relationship of early stem and crown catarrhines. Here we describe the partial cranium of a new medium-sized (about 15-20 kg) fossil catarrhine, Saadanius hijazensis, dated to 29-28 Myr ago. Comparative anatomy and cladistic analysis shows that Saadanius is an advanced stem catarrhine close to the base of the hominoid-cercopithecoid clade. Saadanius is important for assessing competing hypotheses about the ancestral morphotype for crown catarrhines 1,12-14 , early catarrhine phylogeny 12,15 and the age of hominoid-cercopithecoid divergence 11. Saadanius has a tubular ectotympanic but lacks synapomorphies of either group of crown Catarrhini, and we infer that the hominoidcercopithecoid split happened later, between 29-28 and 24 Myr ago. The catarrhine fossil record subsequent to propliopithecoids was unknown except for isolated dentitions of the late-Oligocene Kamoyapithecus hamiltoni from Kenya 16 until the Afro-Arabian early Miocene (about 23-16 Myr ago) diversification of apes 5,16 (considered as basal or 'eo' 17-hominoids, and/or late stem catarrhines and placed in 'Proconsuloidea' 3,12 and 'Dendropithecoidea' 3,18) and cercopithecoids 2,4 (Supplementary Information). The paucity of fossil evidence from about 30-23 Myr ago has inhibited the testing of competing hypotheses about the attributes of the ancestral morphotype of cercopithecoids and hominoids 1,12-14 , the age of their divergence 11 and the nature of the propliopithecoid-crown-catarrhine relationship 12,15. A new Oligocene catarrhine fossil (SGS-UM 2009-002), preserving substantial facial, palatal and dental morphology, was recently recovered from the top of an oolitic ironstone bone bed of the middle unit of the Shumaysi Formation, at Harrat Al Ujayfa in Al Hijaz Province, western Saudi Arabia (Fig. 1a-c) by a Saudi Geological Survey-University of Michigan expedition. This is the most substantive evidence of catarrhines from the late early Oligocene through to the late Oligocene, further emphasizing Afro-Arabia as the locus of early catarrhine evolution (Fig. 1c). The Shumaysi Formation was deposited before the early Miocene opening of the Red Sea rift 19-21. It rests partly on the late Cretaceous-Eocene Usfan Formation, and is overlain in places by Miocene
... 28″N latitude and 37°07′06″E longitude, some 194 km southeast of Amman and 8 km northeast of ... more ... 28″N latitude and 37°07′06″E longitude, some 194 km southeast of Amman and 8 km northeast of the Al-Umari check point on ... The Natural Resources Authority of Jordan mapping project in the Abar Al-Hazim area, carried out by Rabba (1998), regarded all of the Wadi Esh ...
Protocetidae are middle Eocene (49-37 Ma) archaeocete predators ancestral to later whales. They a... more Protocetidae are middle Eocene (49-37 Ma) archaeocete predators ancestral to later whales. They are found in marine sedimentary rocks, but retain four legs and were not yet fully aquatic. Protocetids have been interpreted as amphibious, feeding in the sea but returning to land to rest.
Partial skeletons of two new fossil whales, Artiocetus clavis and Rodhocetus balochistanensis , a... more Partial skeletons of two new fossil whales, Artiocetus clavis and Rodhocetus balochistanensis , are among the oldest known protocetid archaeocetes. These came from early Lutetian age (47 million years ago) strata in eastern Balochistan Province, Pakistan. Both have an astragalus and cuboid in the ankle with characteristics diagnostic of artiodactyls; R. balochistanensis has virtually complete fore- and hind limbs. The new skeletons are important in augmenting the diversity of early Protocetidae, clarifying that Cetacea evolved from early Artiodactyla rather than Mesonychia and showing how early protocetids swam.
Over about 10 million years, the ancestors of whales transformed from herbivorous, deer-like, ter... more Over about 10 million years, the ancestors of whales transformed from herbivorous, deer-like, terrestrial mammals into carnivorous and fully aquatic cetaceans. Protocetids are Eocene whales that represent a unique semiaquatic stage in that dramatic evolutionary transformation. Here, we report on a new medium-sized protocetid, <i>Phiomicetus anubis</i> gen. et sp. nov., consisting of a partial skeleton from the middle Eocene (Lutetian) of the Fayum Depression in Egypt. The new species differs from other protocetids in having large, elongated temporal fossae, anteriorly placed pterygoids, elongated parietals, an unfused mandibular symphysis that terminates at the level of P<sub>3</sub> and a relatively enlarged I<sub>3</sub>. Unique features of the skull and mandible suggest a capacity for more efficient oral mechanical processing than the typical protocetid condition, thereby allowing for a strong raptorial feeding style. Phylogenetic analysis nest...
A Priabonian (late Eocene) neoselachian fauna of sharks and rays is known from marine strata in t... more A Priabonian (late Eocene) neoselachian fauna of sharks and rays is known from marine strata in the foothills of Minqar Tabaghbagh, near the southwestern corner of the Qattara Depression in the Western Desert of Egypt. Neoselachian remains were collected from the lower glauconitic shales and mudstones of the Daba’a Formation, which is a western equivalent of the Qasr El-Sagha Formation found in the eastern part of the Western Desert. Neoselachians studied here are macro-scale, collected on the surface, and known either from teeth or rostral remains. Taxonomic evaluation shows that the neoselachians belong to five orders, 11 families, 19 genera, and 24 species. The species are: Hexanchus agassizi, Carcharias sp., Otodus cf. O. sokolowi, Brachycarcharias cf. B. twiggsensis, Macrorhizodus praecursor, Xiphodolamia serrata, Alopias alabamensis, Alopias sp., Abdounia aff. A. minutissima, Misrichthys stromeri, Carcharhinus sp. 1, Carcharhinus sp. 2, Galeocerdo sp. 1, Galeocerdo sp. 2, Nega...
Millericrinids constitute an order of extinct articulate crinoids that range from the Middle Tria... more Millericrinids constitute an order of extinct articulate crinoids that range from the Middle Triassic to the Late Cretaceous. Based on partially articulated material comprising calyces, columns, and holdfasts, six species (one of them new) belonging to five different genera are described from the Late Jurassic of Spain for the first time. They include Angulocrinus tomaszi n. sp. from the Yatova Formation (middle-upper Oxfordian); and Millericrinus milleri, Liliocrinus polydactylus, Pomatocrinus hoferi, Pomatocrinus cf. mespiliformis, and Apiocrinites cf. parkinsoni from the Sot de Chera Formation (Kimmeridgian). A. tomaszi n. sp. lived in association with sponges and other invertebrates in relatively shallow, open platform areas, with variable depths near storm wave base. The assemblage from the Sot de Chera Formation is more diverse and preliminary taphonomic and sedimentological information suggest that these millericrinids lived in high-energy conditions from shore-face environme...
Stalked crinoids have generally been overlooked when considering trace fossil makers — largely be... more Stalked crinoids have generally been overlooked when considering trace fossil makers — largely because they were long considered fully sessile. However, observations both in the field and in laboratory experiments revealed that some members of the order Isocrinida use their arms to actively move along the bottom, dragging the stalk behind. This activity leaves distinct traces on the sediment surface. Here, we re-examined time-lapse movies made in 2017 and crawling traces produced by stalked crinoids (the isocrinine Metacrinus rotundus) in previously published neoichnological experiments using new 3D digitization techniques (laser scanning and photogrammetry) in order to provide a more detailed 3D morphology of these traces. These data reveal some previously unnoticed crawling behavior and features of the traces of M. rotundus. We also demonstrate that crinoid-bearing beds are sometimes associated with ichnofossils that can be potentially interpreted as crinoid crawling traces. These...
Proceedings of the Royal Society B: Biological Sciences
Over about 10 million years, the ancestors of whales transformed from herbivorous, deer-like, ter... more Over about 10 million years, the ancestors of whales transformed from herbivorous, deer-like, terrestrial mammals into carnivorous and fully aquatic cetaceans. Protocetids are Eocene whales that represent a unique semiaquatic stage in that dramatic evolutionary transformation. Here, we report on a new medium-sized protocetid, Phiomicetus anubis gen. et sp. nov., consisting of a partial skeleton from the middle Eocene (Lutetian) of the Fayum Depression in Egypt. The new species differs from other protocetids in having large, elongated temporal fossae, anteriorly placed pterygoids, elongated parietals, an unfused mandibular symphysis that terminates at the level of P 3 , and a relatively enlarged I 3 . Unique features of the skull and mandible suggest a capacity for more efficient oral mechanical processing than the typical protocetid condition, thereby allowing for a strong raptorial feeding style. Phylogenetic analysis nests Phiomicetus within the paraphyletic Protocetidae, as the m...
Crinoid and blastoid diversity and abundance peaked during the Late Devonian – early Mississippia... more Crinoid and blastoid diversity and abundance peaked during the Late Devonian – early Mississippian (Famennian – Viséan), an interval known as the Age of Crinoids. In North America, localities with maximum crinoid and blastoid diversity and abundance occurred in carbonate ramp and delta platform and slope deposits offshore from the Appalachian tectonic highlands. Living shallow-water crinoids reached maximum species diversity and abundance in more heterotrophic waters of the Indo-West Pacific Coral Triangle, Great Barrier Reef, and Caribbean crinoids are less diverse around coral-rich offshore islands and atolls in more oligotrophic waters. Ancient crinoids and blastoids were suspension feeders, limited by very narrow food grooves to capturing very small food particles. Blastoids in particular had food grooves <300 μm width, but crinoid food grooves were </= 100 μm to >1.25 mm, with most species <400 μm. Living crinoids, both unstalked and stalked, also have narrow food g...
Predation, an important driver of natural selection, is studied in the fossil record using quanti... more Predation, an important driver of natural selection, is studied in the fossil record using quantifiable traces like drill holes produced by gastropods and repair scars produced after durophagous attacks. Despite the abundance of such records in molluscan prey, predation records of micromolluscs (<5mm) remain largely unexplored. Using a Miocene assemblage of microgastropods from the Quilon Limestone, India, we established the predator-prey dynamics with the help of costbenefit analyses. The overall predation intensity, measured by drilling frequency (DF) and repair scare frequency (RF) is low (DF = 0.06, RF= 0.04). The predation intensity does not depend on the relative abundance of prey families suggesting a non-random prey selection regardless of the encounter frequency. Predation is selective as revealed by higher predation observed in prey of specific family identity, ornamentation, and body size. The smallest size class has the lowest DF and RF supporting a negative size refu...
Abundant, well-preserved archaic whale remains from Fayum deposits have facilitated our understan... more Abundant, well-preserved archaic whale remains from Fayum deposits have facilitated our understanding of the evolutionary transition of whales from the terrestrial to the marine realms (e.g., Gingerich and Smith, 1990; Gingerich et al., 1990; Gingerich and Uhen, 1996). However, the turtle remains from these formations have received significantly less attention and are still poorly understood. Among them are members of the subtribe Stereogenyina (Gaffney et al., 2011), previously referred to as the Shweboemysgroup turtles (Broin, 1988). Although similar to other podocnemidids in many respects, these pleurodires had an autapomorphic palatal structure that consisted of a
Apex predators live at the top of an ecological pyramid, preying on animals in the pyramid below ... more Apex predators live at the top of an ecological pyramid, preying on animals in the pyramid below and normally immune from predation themselves. Apex predators are often, but not always, the largest animals of their kind. The living killer whale Orcinus orca is an apex predator in modern world oceans. Here we focus on an earlier apex predator, the late Eocene archaeocete Basilosaurus isis from Wadi Al Hitan in Egypt, and show from stomach contents that it fed on smaller whales (juvenile Dorudon atrox) and large fishes (Pycnodus mokattamensis). Our observations, the first direct evidence of diet in Basilosaurus isis, confirm a predator-prey relationship of the two most frequently found fossil whales in Wadi Al-Hitan, B. isis and D. atrox. This extends our understanding of their paleoecology. Late Eocene Basilosaurus isis, late Miocene Livyatan melvillei, and modern Orcinus orca are three marine apex predators known from relatively short intervals of time. Little is known about whales as apex predators through much of the Cenozoic era, and whales as apex predators deserve more attention than they have received.
Understanding the timing and character of the expansion of Homo sapiens out of Africa is critical... more Understanding the timing and character of the expansion of Homo sapiens out of Africa is critical for inferring the colonization and admixture processes that underpin global population history. It has been argued that dispersal out of Africa had an early phase, particularly ~130-90 thousand years ago (ka), that reached only the East Mediterranean Levant, and a later phase, ~60-50 ka, that extended across the diverse environments of Eurasia to Sahul. However, recent findings from East Asia and Sahul challenge this model. Here we show that H. sapiens was in the Arabian Peninsula before 85 ka. We describe the Al Wusta-1 (AW-1) intermediate phalanx from the site of Al Wusta in the Nefud desert, Saudi Arabia. AW-1 is the oldest directly dated fossil of our species outside Africa and the Levant. The palaeoenvironmental context of Al Wusta demonstrates that H. sapiens using Middle Palaeolithic stone tools dispersed into Arabia during a phase of increased precipitation driven by orbital for...
Biological and physical factors govern the distribution of fossils, but it is not always clear wh... more Biological and physical factors govern the distribution of fossils, but it is not always clear which is more important. The preservation of late Eocene vertebrates at the UNESCO World Heritage site of Wadi Al-Hitan, Western Desert of Egypt, is controlled primarily by the physical processes responsible for sequence stratigraphic architecture on a siliciclastic shelf. Three types of stratigraphic surface, each characterized by a taxonomically and taphonomically distinct fossil assemblage, yield most of the known vertebrate fossils. Complete, partially articulated whale skeletons, primarily Basilosaurus isis, are abundant in offshore marine flooding surfaces (MFS) in the late transgressive systems tract (TST) of the first Priabonian sequence (TA4.1), where low net sedimentation rates and environmental averaging in offshore environments promoted the accumulation of carcasses on traceable stratigraphic surfaces. Complete, well-articulated whales, primarily Dorudon atrox, are more widely scattered on minor erosion surfaces in rapidly accumulating shoreface sediments of the overlying falling stage systems tract. Fragmented and abraded vertebrate remains are abundant and diverse in a discontinuous conglomerate that marks the first sequence boundary above the base of the Priabonian (Pr-2), which has not been previously recognized in Egypt, but which formed incised valleys with at least 45 m of total relief. Fossils in this variably thick lag conglomerate include skeletal elements reworked by rivers from underlying marine deposits and bones of terrestrial animals living in the fluvial environment. Marginal marine vertebrates, primarily dugongs, occur on shelly marine ravinement surfaces above Pr-2, in the early TST of the second Priabonian sequence. Most vertebrate remains in Wadi Al-Hitan occur in condensed stratigraphic intervals and taxonomic composition changes with sequence position, both important considerations in interpretation of paleobiological patterns. PALAIOS PETERS ET AL. FIGURE 2-Late Eocene-Oligocene timescale, inferred cycles in eustatic sea level, and third-order sequence boundaries (modified from Hardenbol et al., 1998). Studied interval shown (approximately) by hatched area. CN ϭ calcareous nannoplankton zones; PF ϭ planktonic foraminfera zones; SB ϭ sequence boundary.
ABSTRACT Remingtonocetids are semiaquatic archaeocete cetaceans known for their elongated narrow ... more ABSTRACT Remingtonocetids are semiaquatic archaeocete cetaceans known for their elongated narrow skulls, long necks, and robust pelves and hind limbs. The family currently includes five genera (Attockicetus, Remingtonocetus, Dalanistes, Andrewsiphius, and Kutchicetus), which are known principally from the middle-to-late Lutetian Domanda Formation of Pakistan and the late Lutetian Harudi Formation of India. Some specimens have been recovered from other formations; however, all previous occurrences have been restricted to the Lutetian of Indo-Pakistan. A new genus of remingtonocetid cetacean has been recovered from the late Lutetian Midawara Formation of Egypt. The specimen includes a left innominate with a complete ilium, ischium, and acetabulum; a nearly complete left femur; a four-vertebra sacrum; and partial lumbar and anterior caudal vertebrae. The long, broad ilium and near closure of the acetabular notch compare closely with the innominates of other remingtonocetids, though the ischium is much broader and flatter. The femur is generally similar in size and shape to known specimens of Remingtonocetus, but has a more vertically-oriented head and neck and a shaft with a more circular cross-section that lacks a conspicuous lateral keel. The sacrum is composed of four vertebrae, three of which are at least partially fused together as in other remingtonocetids, with very large dorsal sacral foramina. A well-preserved lumbar vertebra has curved zygapophyses, reniform epiphyses, and short transverse processes with only a modest degree of anterior or ventral inclination, comparing closely with lumbar vertebrae of Remingtonocetus. However, partial neural arches suggest that lumbar neural spines were inclined posteriorly rather than anteriorly. The new specimen increases the known taxonomic diversity of Remingtonocetidae, illustrates additional variation in the morphology and locomotor repertoire of the group, and provides the first evidence of the family in Africa.
Proceedings of the Royal Society B: Biological Sciences, 2012
Our understanding of locomotor evolution in anthropoid primates has been limited to those taxa fo... more Our understanding of locomotor evolution in anthropoid primates has been limited to those taxa for which good postcranial fossil material and appropriate modern analogues are available. We report the results of an analysis of semicircular canal size variation in 16 fossil anthropoid species dating from the Late Eocene to the Late Miocene, and use these data to reconstruct evolutionary changes in locomotor adaptations in anthropoid primates over the last 35 Ma. Phylogenetically informed regression analyses of semicircular canal size reveal three important aspects of anthropoid locomotor evolution: (i) the earliest anthropoid primates engaged in relatively slow locomotor behaviours, suggesting that this was the basal anthropoid pattern; (ii) platyrrhines from the Miocene of South America were relatively agile compared with earlier anthropoids; and (iii) while the last common ancestor of cercopithecoids and hominoids likely was relatively slow like earlier stem catarrhines, the results...
It is widely understood that Hominoidea (apes and humans) and Cercopithecoidea (Old World monkeys... more It is widely understood that Hominoidea (apes and humans) and Cercopithecoidea (Old World monkeys) have a common ancestry as Catarrhini deeply rooted in Afro-Arabia 1-4. The oldest stem Catarrhini in the fossil record are Propliopithecoidea, known from the late Eocene to early Oligocene epochs (roughly 35-30 Myr ago) of Egypt, Oman and possibly Angola 5-10. Genome-based estimates for divergence of hominoids and cercopithecoids range into the early Oligocene 11 ; however, the mid-to-late Oligocene interval from 30 to 23 Myr ago has yielded little fossil evidence documenting the morphology of the last common ancestor of hominoids and cercopithecoids, the timing of their divergence, or the relationship of early stem and crown catarrhines. Here we describe the partial cranium of a new medium-sized (about 15-20 kg) fossil catarrhine, Saadanius hijazensis, dated to 29-28 Myr ago. Comparative anatomy and cladistic analysis shows that Saadanius is an advanced stem catarrhine close to the base of the hominoid-cercopithecoid clade. Saadanius is important for assessing competing hypotheses about the ancestral morphotype for crown catarrhines 1,12-14 , early catarrhine phylogeny 12,15 and the age of hominoid-cercopithecoid divergence 11. Saadanius has a tubular ectotympanic but lacks synapomorphies of either group of crown Catarrhini, and we infer that the hominoidcercopithecoid split happened later, between 29-28 and 24 Myr ago. The catarrhine fossil record subsequent to propliopithecoids was unknown except for isolated dentitions of the late-Oligocene Kamoyapithecus hamiltoni from Kenya 16 until the Afro-Arabian early Miocene (about 23-16 Myr ago) diversification of apes 5,16 (considered as basal or 'eo' 17-hominoids, and/or late stem catarrhines and placed in 'Proconsuloidea' 3,12 and 'Dendropithecoidea' 3,18) and cercopithecoids 2,4 (Supplementary Information). The paucity of fossil evidence from about 30-23 Myr ago has inhibited the testing of competing hypotheses about the attributes of the ancestral morphotype of cercopithecoids and hominoids 1,12-14 , the age of their divergence 11 and the nature of the propliopithecoid-crown-catarrhine relationship 12,15. A new Oligocene catarrhine fossil (SGS-UM 2009-002), preserving substantial facial, palatal and dental morphology, was recently recovered from the top of an oolitic ironstone bone bed of the middle unit of the Shumaysi Formation, at Harrat Al Ujayfa in Al Hijaz Province, western Saudi Arabia (Fig. 1a-c) by a Saudi Geological Survey-University of Michigan expedition. This is the most substantive evidence of catarrhines from the late early Oligocene through to the late Oligocene, further emphasizing Afro-Arabia as the locus of early catarrhine evolution (Fig. 1c). The Shumaysi Formation was deposited before the early Miocene opening of the Red Sea rift 19-21. It rests partly on the late Cretaceous-Eocene Usfan Formation, and is overlain in places by Miocene
... 28″N latitude and 37°07′06″E longitude, some 194 km southeast of Amman and 8 km northeast of ... more ... 28″N latitude and 37°07′06″E longitude, some 194 km southeast of Amman and 8 km northeast of the Al-Umari check point on ... The Natural Resources Authority of Jordan mapping project in the Abar Al-Hazim area, carried out by Rabba (1998), regarded all of the Wadi Esh ...
Protocetidae are middle Eocene (49-37 Ma) archaeocete predators ancestral to later whales. They a... more Protocetidae are middle Eocene (49-37 Ma) archaeocete predators ancestral to later whales. They are found in marine sedimentary rocks, but retain four legs and were not yet fully aquatic. Protocetids have been interpreted as amphibious, feeding in the sea but returning to land to rest.
Partial skeletons of two new fossil whales, Artiocetus clavis and Rodhocetus balochistanensis , a... more Partial skeletons of two new fossil whales, Artiocetus clavis and Rodhocetus balochistanensis , are among the oldest known protocetid archaeocetes. These came from early Lutetian age (47 million years ago) strata in eastern Balochistan Province, Pakistan. Both have an astragalus and cuboid in the ankle with characteristics diagnostic of artiodactyls; R. balochistanensis has virtually complete fore- and hind limbs. The new skeletons are important in augmenting the diversity of early Protocetidae, clarifying that Cetacea evolved from early Artiodactyla rather than Mesonychia and showing how early protocetids swam.
Over about 10 million years, the ancestors of whales transformed from herbivorous, deer-like, ter... more Over about 10 million years, the ancestors of whales transformed from herbivorous, deer-like, terrestrial mammals into carnivorous and fully aquatic cetaceans. Protocetids are Eocene whales that represent a unique semiaquatic stage in that dramatic evolutionary transformation. Here, we report on a new medium-sized protocetid, <i>Phiomicetus anubis</i> gen. et sp. nov., consisting of a partial skeleton from the middle Eocene (Lutetian) of the Fayum Depression in Egypt. The new species differs from other protocetids in having large, elongated temporal fossae, anteriorly placed pterygoids, elongated parietals, an unfused mandibular symphysis that terminates at the level of P<sub>3</sub> and a relatively enlarged I<sub>3</sub>. Unique features of the skull and mandible suggest a capacity for more efficient oral mechanical processing than the typical protocetid condition, thereby allowing for a strong raptorial feeding style. Phylogenetic analysis nest...
A Priabonian (late Eocene) neoselachian fauna of sharks and rays is known from marine strata in t... more A Priabonian (late Eocene) neoselachian fauna of sharks and rays is known from marine strata in the foothills of Minqar Tabaghbagh, near the southwestern corner of the Qattara Depression in the Western Desert of Egypt. Neoselachian remains were collected from the lower glauconitic shales and mudstones of the Daba’a Formation, which is a western equivalent of the Qasr El-Sagha Formation found in the eastern part of the Western Desert. Neoselachians studied here are macro-scale, collected on the surface, and known either from teeth or rostral remains. Taxonomic evaluation shows that the neoselachians belong to five orders, 11 families, 19 genera, and 24 species. The species are: Hexanchus agassizi, Carcharias sp., Otodus cf. O. sokolowi, Brachycarcharias cf. B. twiggsensis, Macrorhizodus praecursor, Xiphodolamia serrata, Alopias alabamensis, Alopias sp., Abdounia aff. A. minutissima, Misrichthys stromeri, Carcharhinus sp. 1, Carcharhinus sp. 2, Galeocerdo sp. 1, Galeocerdo sp. 2, Nega...
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Papers by Iyad Zalmout