Dr Imran Rahman
Deputy Head of Research
Email: imran.rahman@oum.ox.ac.uk
Phone: +44 (0)1865 272 996
College profile page: Junior Research Fellow, St Cross College
Twitter: @VirtualPalaeo
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Research summary
Research summary
Dr Rahman’s research uses echinoderms as a model group for uncovering the origin and early evolution of animals more broadly. His work is focused on Palaeozoic fossils, which document the earliest steps in the evolution of the echinoderm body plan. Fossils are analysed with the aid of high-resolution X-ray tomography and computer simulations (e.g. computational fluid dynamics), providing new insights into their morphology, systematics and function. This has informed rigorous tests of long-standing hypotheses concerning the mode of life, phylogenetic relationships and evolutionary history of early echinoderms, with implications for understanding the Cambrian explosion and the emergence of animals more generally.
Related research interests include Ediacaran organisms and their ecosystems, the anatomy and development of deuterostomes and techniques for three-dimensional visualization and analysis of fossil and modern specimens.
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Imran Rahman is Deputy Head of Research at Oxford University Museum of Natural History, and is currently supported by a Museum Research Fellowship. He is also a Junior Research Fellow at St Cross College. Prior to this, Imran was supported by an 1851 Research Fellowship split between the University of Bristol and the Oxford University Museum of Natural History.
Imran obtained an MSc in Palaeobiology from University College London and a PhD on Palaeozoic fossil echinoderms from Imperial College London under the supervision of Dr Mark Sutton. After his PhD, Imran undertook an MSc in Evolutionary Genetics and Genomics at the University of Manchester to gain practical experience in molecular biology and bioinformatics. This was followed by a NERC Postdoctoral Research Fellowship split between the Universities of Birmingham and Bristol.
Featured publications
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An edrioasteroid from the Silurian Herefordshire Lagerstätte of England reveals the nature of the water vascular system in an extinct echinoderm.
Briggs, DEG, Siveter, DJ, Siveter, DJ, Sutton, MD, Rahman, IA2017|Journal article|Proceedings. Biological sciencesEchinoderms are unique in having a water vascular system with tube feet, which perform a variety of functions in living forms. Here, we report the first example of preserved tube feet in an extinct group of echinoderms. The material, from the Silurian Herefordshire Lagerstätte, UK, is assigned to a new genus and species of rhenopyrgid edrioasteroid, Heropyrgus disterminus The tube feet attach to the inner surface of compound interradial plates and form two sets, an upper and a lower, an arrangement never reported previously in an extant or extinct echinoderm. Cover plates are absent and floor plates are separated creating a large permanent entrance to the interior of the oral area. The tube feet may have captured food particles that entered the oral area and/or enhanced respiration. The pentameral symmetry of the oral surface transitions to eight columns in which the plates are vertically offset resulting in a spiral appearance. This change in symmetry may reflect flexibility in the evolutionary development of the axial and extraxial zones in early echinoderm evolution.Animals, Echinodermata, Water, Fossils, England -
The Cambrian Substrate Revolution and the early evolution of attachment in suspension-feeding echinoderms
Zamora, S, Deline, B, Javier Alvaro, J, Rahman, IA2017|Journal article|EARTH-SCIENCE REVIEWSPalaeoecology, Evolution, Seafloor, Attachment -
Cambrian cinctan echinoderms shed light on feeding in the ancestral deuterostome.
Rahman, IA, Zamora, S, Falkingham, PL, Phillips, JC2015|Journal article|Proceedings. Biological sciencesReconstructing the feeding mode of the latest common ancestor of deuterostomes is key to elucidating the early evolution of feeding in chordates and allied phyla; however, it is debated whether the ancestral deuterostome was a tentaculate feeder or a pharyngeal filter feeder. To address this, we evaluated the hydrodynamics of feeding in a group of fossil stem-group echinoderms (cinctans) using computational fluid dynamics. We simulated water flow past three-dimensional digital models of a Cambrian fossil cinctan in a range of possible life positions, adopting both passive tentacular feeding and active pharyngeal filter feeding. The results demonstrate that an orientation with the mouth facing downstream of the current was optimal for drag and lift reduction. Moreover, they show that there was almost no flow to the mouth and associated marginal groove under simulations of passive feeding, whereas considerable flow towards the animal was observed for active feeding, which would have enhanced the transport of suspended particles to the mouth. This strongly suggests that cinctans were active pharyngeal filter feeders, like modern enteropneust hemichordates and urochordates, indicating that the ancestral deuterostome employed a similar feeding strategy.Animals, Echinodermata, Feeding Behavior, Fossils, Computer Simulation, Biological Evolution, Hydrodynamics -
Organismal Biology: Suspension feeding in the enigmatic ediacaran organism tribrachidium demonstrates complexity of Neoproterozoic ecosystems
Rahman, IA, Darroch, SAF, Racicot, RA, Laflamme, M2015|Journal article|Science Advances© 2018 The Authors. The first diverse and morphologically complex macroscopic communities appear in the late Ediacaran period, 575 to 541 million years ago (Ma). The enigmatic organisms that make up these communities are thought to have formed simple ecosystems characterized by a narrow range of feeding modes, with most restricted to the passive absorption of organic particles (osmotrophy). We test between competing feeding models for the iconic Ediacaran organism Tribrachidium heraldicum using computational fluid dynamics. We show that the external morphology of Tribrachidium passively directs water flow toward the apex of the organism and generates low-velocity eddies above apical "pits." These patterns of fluid flow are inconsistent with osmotrophy and instead support the interpretation of Tribrachidium as a passive suspension feeder. This finding provides the oldest empirical evidence for suspension feeding at 555 to 550 Ma, ∼10 million years before the Cambrian explosion, and demonstrates that Ediacaran organisms formed more complex ecosystems in the latest Precambrian, involving a larger number of ecological guilds, than currently appreciated. -
Early post-metamorphic, Carboniferous blastoid reveals the evolution and development of the digestive system in echinoderms.
Rahman, IA, Waters, JA, Sumrall, CD, Astolfo, A2015|Journal article|Biology lettersInferring the development of the earliest echinoderms is critical to uncovering the evolutionary assembly of the phylum-level body plan but has long proven problematic because early ontogenetic stages are rarely preserved as fossils. Here, we use synchrotron tomography to describe a new early post-metamorphic blastoid echinoderm from the Carboniferous (approx. 323 Ma) of China. The resulting three-dimensional reconstruction reveals a U-shaped tubular structure in the fossil interior, which is interpreted as the digestive tract. Comparisons with the developing gut of modern crinoids demonstrate that crinoids are an imperfect analogue for many extinct groups. Furthermore, consideration of our findings in a phylogenetic context allows us to reconstruct the evolution and development of the digestive system in echinoderms more broadly; there was a transition from a straight to a simple curved gut early in the phylum's evolution, but additional loops and coils of the digestive tract (as seen in crinoids) were not acquired until much later.Gastrointestinal Tract, Animals, Echinodermata, Phylogeny, Fossils, China, Biological Evolution
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