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- Australian Systematic Botany
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Leguminosae are one of the most diverse flowering-plant groups today, but the evolutionary history of the family remains obscure because of the scarce early fossil record, particularly from lowland tropics. Here, we report ~500 compression or impression specimens with distinctive legume features collected from the Cerrejón and Bogotá Formations, Middle to Late Paleocene of Colombia. The specimens were segregated into eight fruit and six leaf morphotypes. Two bipinnate leaf morphotypes are confidently placed in the Caesalpinioideae and are the earliest record of this subfamily. Two of the fruit morphotypes are placed in the Detarioideae and Dialioideae. All other fruit and leaf morphotypes show similarities with more than one subfamily or their affinities remain uncertain. The abundant fossil fruits and leaves described here show that Leguminosae was the most important component of the earliest rainforests in northern South America c. 60–58 million years ago.
First fossil-leaf floras from Brunei Darussalam show dipterocarp dominance in Borneo by the PlioceneThe Malay Archipelago is one of the most biodiverse regions on Earth, but it suffers high extinction risks due to severe anthropogenic pressures. Paleobotanical knowledge provides baselines for the conservation of living analogs and improved understanding of vegetation, biogeography, and paleoenvironments through time. The Malesian bioregion is well studied palynologically, but there have been very few investigations of Cenozoic paleobotany (plant macrofossils) in a century or more. We report the first paleobotanical survey of Brunei Darussalam, a sultanate on the north coast of Borneo that still preserves the majority of its extraordinarily diverse, old-growth tropical rainforests. We discovered abundant compression floras dominated by angiosperm leaves at two sites of probable Pliocene age: Berakas Beach, in the Liang Formation, and Kampong Lugu, in an undescribed stratigraphic unit. Both sites also yielded rich palynofloral assemblages from the macrofossil-bearing beds, indicating lowland fern-dominated swamp (Berakas Beach) and mangrove swamp (Kampong Lugu) depositional environments. Fern spores from at least nine families dominate both palynological assemblages, along with abundant fungal and freshwater algal remains, rare marine microplankton, at least four mangrove genera, and a diverse rainforest tree and liana contribution (at least 19 families) with scarce pollen of Dipterocarpaceae, today’s dominant regional life form. Compressedmore »
Can Geometric Morphometric Analyses of Limb Shape Reveal Ecomorphological Patterns Across the Evolutionary History of Synapsida?Extant Mammalia are the only living representatives of the larger clade known as Synapsida, which has a continuous fossil record from around 320 million years ago to today. Despite the fact that much of the ecological diversity of mammals has been considered in light of limb morphology, the deep time origin of synapsid limb diversity and its influence on ecological diversity has received less attention. Here, we present shape analyses focusing on the forelimbs of the two earliest synapsid radiations (“pelycosaurs”, and pre-mammaliaforme Therapsida) in comparison to a broad sample of extant Mammalia. Using an expansive geometric morphometric data set, comprised of 384 fossil specimens and 148 extant mammalian specimens, we sought evidence for ecomorphological signals that could provide insight on the ecology of the earliest synapsids. Collecting shape data of humeral and ulnar elements from an extant sample representing multiple known eco morphologies provided the framework for a comparative exploration of extinct ecomorphologies, associated specifically with locomotion. Our results show that distal humeral shape is not informative of broad locomotor ecomorphologies in early fossil Synapsida. In contrast, proximal humeral shape shows a more complex pattern that suggests shape similarity between basal synapsids and members of extant Perissodactyla, and certainmore »
Hyainailourine and teratodontine cranial material from the late Eocene of Egypt and the application of parsimony and Bayesian methods to the phylogeny and biogeography of Hyaenodonta (Placentalia, Mammalia)
Hyaenodonta is a diverse, extinct group of carnivorous mammals that included weasel- to rhinoceros-sized species. The oldest-known hyaenodont fossils are from the middle Paleocene of North Africa and the antiquity of the group in Afro-Arabia led to the hypothesis that it originated there and dispersed to Asia, Europe, and North America. Here we describe two new hyaenodont species based on the oldest hyaenodont cranial specimens known from Afro-Arabia. The material was collected from the latest Eocene Locality 41 (L-41, ∼34 Ma) in the Fayum Depression, Egypt.
Akhnatenavus nefertiticyonsp. nov. has specialized, hypercarnivorous molars and an elongate cranial vault. In A. nefertiticyonthe tallest, piercing cusp on M1–M2is the paracone. Brychotherium ephalmosgen. et sp. nov. has more generalized molars that retain the metacone and complex talonids. In B. ephalmosthe tallest, piercing cusp on M1–M2is the metacone. We incorporate this new material into a series of phylogenetic analyses using a character-taxon matrix that includes novel dental, cranial, and postcranial characters, and samples extensively from the global record of the group. The phylogenetic analysis includes the first application of Bayesian methods to hyaenodont relationships. B. ephalmosis consistently placed within Teratodontinae, an Afro-Arabian clade with several generalist and hypercarnivorous forms, and Akhnatenavusis consistently recovered in Hyainailourinae as part of an Afro-Arabianmore »
Abstract The fossil record of Marsilea is challenging to assess, due in part to unreliable reports and conflicting opinions regarding the proper application of the names Marsilea and Marsileaceaephyllum to fossil leaves and leaflets similar to those of modern Marsilea . Specimens examined for this study include material assigned to Marsileaceaephyllum johnhallii , purportedly the oldest fossil record of a Marsilea -like sporophyte from the Lower Cretaceous of the Dakota Formation, Kansas, U.S.A.; leaves and leaf whorls of the extinct aquatic angiosperm Fortuna from several Late Cretaceous and Paleocene localities in western North America; and leaves and leaflets resembling Marsilea from the Eocene Green River Formation, Colorado and Utah, U.S.A. Literature on the fossil record of Marsilea was also reviewed. As a result, several taxonomic changes are proposed. Marsileaceaephyllum johnhallii is reinterpreted as an aquatic angiosperm that shares some architectural features with the genus Fortuna , although Marsileaceaephyllum is here maintained as a distinct genus with an emended diagnosis; under this reinterpretation, the name Marsileaceaephyllum can no longer be applied to sporophyte organs with affinities to Marsileaceae. Three valid fossil Marsilea species are recognized on the basis of sporophyte material that includes characteristic quadrifoliolate leaves and reticulate-veined leaflets: Marsilea campanicamore »