DOCSLIB.ORG

I:\AA-TYPESET\PALAEO\2018-2019\WHITNEY.Vp

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
I:\AA-TYPESET\PALAEO\2018-2019\WHITNEY.Vp Histological evi de nce of tra u ma i n t us ks of so ut her n Africa n dicy no do nts § Megan R. Whitney 1, * , Y u e n Ti n g Ts e 1 & C hristia n A. Si dor 1, 2 1 Depart ment of Biology and Burke Museu m, University of Washington, Seattle, Washington, 98195, U.S. A. 2 Evol utio nary St udies I nstit ute, U niversity of the Wit watersra nd, Joha n nesb urg, So uth Africa Received 11 May 2018. Accepted 20 Dece mber 2018 Dicy no do nts were a cla de of globally- distrib ute d t hera psi ds k no w n for t heir ab u n da nce i n t he fossil recor d a n d for s urvivi ng t he Per mo-Triassic mass exti nctio n. T he gro u p ha d disti nctive de ntal a da ptatio ns i ncl u di ng a beak a n d, i n ma ny s pecies, paire d maxillary t usks. T he f u nctio n of t hese t usks has lo ng bee n of i nterest, yet re mai ns poorly u n derstoo d. We re port here o n t wo i nsta nces of u n us ual morphology in tusk dentine fro m speci mens of: 1) Lystrosa ur us fro m the Karoo Basin of South Africa and, 2) an unidentified dicy no do ntoi d fro m t he Lua ng wa Basi n of Za mbia. I n bot h, t he cross-sectio nal s ha pe of t he t usk root is lobe d a n d i nfol de d, w hic h histological feat ures s uggest is a res ult of ab nor mal de nti ne de positio n. We i nfer t hat t his ab nor mal mor p hology is likely t he co nse - q ue nce of tra u ma give n its re parative nat ure a n d str uct ural si milarities to tra u ma-relate d mor p hologies re porte d i n t he t usks of mo der n ele p ha nts. T his st u dy de mo nstrates t hat histological sa m pli ng of dicy no do nt t usks ca n s he d lig ht o n t he biology of t his i m porta nt cla de of t hera psi ds. Key words : Dicy no do ntia, Triassic, So ut h Africa, Za mbia, Per mia n, pat hology, de nti ne. Palaeontologia africana 2019. ©2019 Megan R. Whitney, Yuen Ting Tse & Christian A. Sidor. This is an open-access article published under the Creative Co m mons Attrib utio n 4.0 U nported Lice nse ( C C B Y4.0). To vie w a copy of the lice nse, please visit http://creativeco m mo ns.org/lice nses/by/4.0/ . This lice nse per mits u nrestricted use, distrib utio n, a nd reprod uctio n i n a ny medi u m, provided the origi nal a uthor a nd so urce are credited. This article is per ma ne ntly archived at: http:// wiredspace. wits.ac.za/ha ndle/10539/26243 INTRODUCTION dicynodont speci mens were prepared and thin-sectioned Dicy no do nts evolve d o ne of t he most s pecialize d foo d follo wing standard methods (La m m 2013). In both speci- processi ng syste ms wit hi n t he sy na psi d li neage, c harac- me ns, t he t usks were broke n w here t hey e merge fro m t he terize d by a hor n-covere d beak a n d (ofte nti mes) maxillary maxillae, b ut preserve most of t he root portio n of t he tusks, along with a distinctive ja w hinge ( Cro mpton & t usks. T hi n sectio ns were ma de per pe n dic ular to t he lo ng Hotto n 1967; A ngielczyk 2004). E nlarge d, paire d t usks, axis of t he t usk, gro u n d to a t hick ness of a p proxi mately w hic h are t he na mesake of t he cla de, have lo ng i ntrig ue d 100 µ m, and i maged with a Nikon Eclipse L V100P OL palaeontologists with proposed functions including microscope an d NIS-Ele ments soft ware. foragi ng for foo d, sex ual di mor p his m i n so me s pecies a n d b urro wi ng be havio urs (S ulliva n et al . 2002; Ra y et al . 2 0 0 5; SYSTE MATIC PALAEO NTOLOGY Mo desto & Bot ha- Bri nk 2010; Bot ha- Bri nk 2017). Des pite Synapsida Osbor n, 1903 this variety of proposed roles, gross morphological T hera psi da Broo m, 1905 evi de nce has provi de d little i nsig ht i nto t he f u nctio n of Dicy no do ntia O we n, 1859 dicy no do nt t usks. Dicynodontoidea O we n, 1859 Here we describe t he histology of t wo t usks a n d t heir surrounding hard tissues in speci mens of Lystrosa ur us Dicy no do ntoi dea i n det. fro m the Karoo Basin of South Africa and an indeter mi - Referred speci me n . N H C C LB836, tusk-bearing left and nate dicynodontoid (possibly Dicy nodo n ) fro m t he ri g ht m a xill a e fr o m o n e i n di vi d u al. Luang wa Basin of Za mbia. Unusually, these speci mens L oc alit y . T his s peci me n was collecte d fro m locality L424, preserve anato my consistent with a develop mental a mediu m-sized outcrop of the upper me mber of the ano maly or pathology, although non-pathological Madu mabisa Mudstone For mation near the southern i nfol de d de nti ne (i.e. plici de nti ne) is see n i n so me border North Luang wa National Park ( Northern Prov - pelycosa ur-gra de sy na psi ds ( Bri nk et al . 2014). Base d o n i nce, Za mbia). Detaile d locality i nfor matio n is available co mparisons with modern tusked ani mals, we conclude fro m N H C C or the authors. t hat tra u ma is t he most likely ex pla natio n for t his a no ma - Lystrosaur us Co pe, 1870 lo us de nti ne a nato my, w hic h ca n provi de i nsig ht i nto t he f u nctio n of t usks i n at least so me dicy no do nts. Lystrosaur us i n d et. Referred speci me ns . S A M-P K- K011603, tusk-bearing right MATERIALS A N D MET H O DS maxilla; S A M- P K- K011604, partial sk ull, i ncl u di ng orbits The tusk and surrounding alveolar ja w bone of the a n d s no ut. * Aut hor for corres po n de nce. E- mail: meg whit @u w.edu L oc alit y . S A M-P K- K011603 was collected near the bound - Palaeontolo gia africana 5 3 : 7 5 – 8 0 — I S S N 2 4 1 0- 4 4 1 8 [ P al a e o nt ol. afr.] O nli n e o nl y Per manently archived on the 17th of January 2019 at the University of the Wit watersrand, Johannesburg, South Africa T hi s arti cl e i s p er m a n e ntl y ar c hi v e d at: htt p:// wir e d s p a c e. wit s. a c. z a/ h a n dl e/ 1 0 5 3 9/ 2 6 2 4 3 ISS N 2410-4418 P al ae o nt. afr. (2019) 5 3 : 75–80 7 5 ary bet ween the far ms Weltrevreden and Ripple mead f u n nel-s ha pe d p ul p cavity (Fig. 1b), i n dicative of a n ever- ( Nieu Bethesda District, Eastern Cape Province) by Dr gro wing tusk (Steenka mp 2003). Roger S mith as field nu mber RS 337, fro m rocks of the N H C C L B836 i ncl u des associate d left a n d rig ht maxillae Triassic u p per Pali ngkloof Me mber of t he Balfo ur For ma - that contain inco mplete tusks (Fig. 2). The caninifor m ti o n ( Lystrosa ur us Asse mblage Zone; S mith & Botha- Brink processes of t he maxillae are a ngle d slig htly per pe n dic u - 2014). S A M-P K- K011604 was also collected by Dr Roger lar to the dorsoventral axis and more r ugose than the S mit h fro m Lo wer Triassic rocks o n t he far m Do nal d 207 surrounding maxillary bone (Fig. 2a). The left maxilla (Fairy dale) i n t he Bet h ulie District, Easter n Ca pe Prov - includes approxi mately 7.5 c m of tusk and the right is ince, approxi mately 54 metres above the inferred slig htly more co m plete, preservi ng 8.4 c m of t usk i ncl u d - Per mo–Triassic boundary.
Load more

Recommended publications
  • On the Stratigraphic Range of the Dicynodont Taxon Emydops (Therapsida: Anomodontia) in the Karoo Basin, South Africa
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Wits Institutional Repository on DSPACE On the stratigraphic range of the dicynodont taxon Emydops (Therapsida: Anomodontia) in the Karoo Basin, South Africa Kenneth D. Angielczyk1*, Jörg Fröbisch2 & Roger M.H. Smith3 1Department of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, BS8 1RJ, United Kingdom 2Department of Biology, University of Toronto at Mississauga, 3359 Mississauga Rd., Mississauga, ON, L5L 1C6, Canada 3Divison of Earth Sciences, South African Museum, P.O. Box 61, Cape Town, 8000 South Africa Received 19 May 2005. Accepted 8 June 2006 The dicynodont specimen SAM-PK-708 has been referred to the genera Pristerodon and Emydops by various authors, and was used to argue that the first appearance of Emydops was in the Tapinocephalus Assemblage Zone in the Karoo Basin of South Africa. However, the specimen never has been described in detail, and most discussions of its taxonomic affinities were based on limited data. Here we redescribe the specimen and compare it to several small dicynodont taxa from the Tapinocephalus and Pristerognathus assemblage zones. Although the specimen is poorly preserved, it possesses a unique combination of features that allows it to be assigned confidently to Emydops. The locality data associated with SAM-PK-708 are vague, but they allow the provenance of the specimen to be narrowed down to a relatively limited area southwest of the town of Beaufort West. Strata from the upper Tapinocephalus Assemblage Zone and the Pristerognathus Assemblage Zone crop out in this area, but we cannot state with certainty from which of these biostratigraphic divisions the specimen was collected.
    [Show full text]
  • By in the Spring of 1929, I Had the Privilege of Acting As Guide To
    O n a S o u t h A fr ic a n M a m m a l -l ik e R e p t il e , B a u r i a c y n o p s . By Lieuwe D. Boonstra (South African Museum, Capetown). With 8 textfigures. (Eingelangt am 18. Dezember 1934.) In the spring of 1929, I had the privilege of acting as guide to Professor and Frau Abel on a short collecting trip in the Great Karroo. When the opportunity was offered me of contributing to the number of Palaeobiologica which is to be issued in honor of Professor Abel’s sixtieth birthday,I recalled with pleasure the time we had spent together. When Professor Abel reads this account of a very interesting reptile from the Karroo, I hope that he may have equally pleasant recollections of our donkey-cart excursions in the Great Karroo of South Africa. On working through the collection of Karroo reptiles which had been sold to the American Museum of Natural History by Dr. R. B room in 1913, I came across some interesting remains of a Bauriamorph. Under the number Amer. Mus. 5622, there is catalogued a good skull, a hind-foot and some limb-bones from the Cynognathus zone at Winnaarsbaken. The skull was first described and figured by B room in 1911. In 1913, and again in 1915, the lateral view was republished. In 1914, sections through the sphen- ethmoidal and prootic regions were published by the same author. When the skull first came under my notice, it had a mass of matrix, containing some limb-bones, attached to the preorbital sur­ face of the snout; the teeth of the left side were partly exposed; parts of the basicranium were cleaned; the matrix on the dorsal surface had been removed in a rough manner, so that part of the D.
    [Show full text]
  • The Role of Fossils in Interpreting the Development of the Karoo Basin
    Palaeon!. afr., 33,41-54 (1997) THE ROLE OF FOSSILS IN INTERPRETING THE DEVELOPMENT OF THE KAROO BASIN by P. J. Hancox· & B. S. Rubidge2 IGeology Department, University of the Witwatersrand, Private Bag 3, Wits 2050, South Africa 2Bernard Price Institute for Palaeontological Research, University of the Witwatersrand, Private Bag 3, Wits 2050, South Africa ABSTRACT The Permo-Carboniferous to Jurassic aged rocks oft1:J.e main Karoo Basin ofSouth Africa are world renowned for the wealth of synapsid reptile and early dinosaur fossils, which have allowed a ten-fold biostratigraphic subdivision ofthe Karoo Supergroup to be erected. The role offossils in interpreting the development of the Karoo Basin is not, however, restricted to biostratigraphic studies. Recent integrated sedimentological and palaeontological studies have helped in more precisely defming a number of problematical formational contacts within the Karoo Supergroup, as well as enhancing palaeoenvironmental reconstructions, and basin development models. KEYWORDS: Karoo Basin, Biostratigraphy, Palaeoenvironment, Basin Development. INTRODUCTION Invertebrate remains are important as indicators of The main Karoo Basin of South Africa preserves a facies genesis, including water temperature and salinity, retro-arc foreland basin fill (Cole 1992) deposited in as age indicators, and for their biostratigraphic potential. front of the actively rising Cape Fold Belt (CFB) in Fossil fish are relatively rare in the Karoo Supergroup, southwestern Gondwana. It is the deepest and but where present are useful indicators of gross stratigraphically most complete of several depositories palaeoenvironments (e.g. Keyser 1966) and also have of Permo-Carboniferous to Jurassic age in southern biostratigraphic potential (Jubb 1973; Bender et al. Africa and reflects changing depositional environments 1991).
    [Show full text]
  • Physical and Environmental Drivers of Paleozoic Tetrapod Dispersal Across Pangaea
    ARTICLE https://doi.org/10.1038/s41467-018-07623-x OPEN Physical and environmental drivers of Paleozoic tetrapod dispersal across Pangaea Neil Brocklehurst1,2, Emma M. Dunne3, Daniel D. Cashmore3 &Jӧrg Frӧbisch2,4 The Carboniferous and Permian were crucial intervals in the establishment of terrestrial ecosystems, which occurred alongside substantial environmental and climate changes throughout the globe, as well as the final assembly of the supercontinent of Pangaea. The fl 1234567890():,; in uence of these changes on tetrapod biogeography is highly contentious, with some authors suggesting a cosmopolitan fauna resulting from a lack of barriers, and some iden- tifying provincialism. Here we carry out a detailed historical biogeographic analysis of late Paleozoic tetrapods to study the patterns of dispersal and vicariance. A likelihood-based approach to infer ancestral areas is combined with stochastic mapping to assess rates of vicariance and dispersal. Both the late Carboniferous and the end-Guadalupian are char- acterised by a decrease in dispersal and a vicariance peak in amniotes and amphibians. The first of these shifts is attributed to orogenic activity, the second to increasing climate heterogeneity. 1 Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK. 2 Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstraße 43, 10115 Berlin, Germany. 3 School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK. 4 Institut
    [Show full text]
  • ON BA U RIA C YNOP S BROOM by A. S. BRINK Bauria Cynops Broom
    ON BA U RIA C YNOP S BROOM By A. S. BRINK ABSTRACT Descriptions of this genus and species, the type of an infraorder, have thus far been based on three individuals. The type in the South African Museum, Cape Town is a complete skull, but somewhat unsatisfactorily preserved and cleaned. The second specimen in the American Museum of Natural History, New York, is a good skull with a portion of the skeleton, but the skull has been damaged in the course of preparation. The third specimen is in the Bernard Price Institute. It is an exceptionally fine specimen, but was only superficially cleaned when described. This specimen also includes a portion of the skeleton. Two additional complete skulls, one somewhat crushed, have since been added to the Bernard Price Institute's collection. This paper describes Bauria cynops Broom on information derived from all five specimens. Illustrations are based on the three specimens in this Institute. Attention h also given to the position of this infraorder relative to other related groups. INTRODUCTION Bauria cynops Broom is a classic Karroo therapsid, the type of the important infraorder Bauriamorpha. The name was introduced by Broom in 1909 and for ~alf a century the infraorder enjoyed a great deal of attention, despite the fact that the type genus is still rather inadequately known. There would appear to be little excuse for this peculiar situation when it is considered that past descrip­ tions have been based on three different specimens which could pass as complete or relatively complete skulls, two with partial skeletons. To these three indivi­ duals a fou.-th and a fifth skull are now added.
    [Show full text]
  • Proceedings of the 18Th Biennial Conference of the Palaeontological Society of Southern Africa Johannesburg, 11–14 July 2014
    Proceedings of the 18th Biennial Conference of the Palaeontological Society of Southern Africa Johannesburg, 11–14 July 2014 Table of Contents Letter of Welcome· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 63 Programme · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 64 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 66 Hand, K.P., Bringing Two Worlds Together: How Earth’s Past and Present Help Us Search for Life on Other Planets · · · · · · · 66 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 67 Erwin, D.H., Major Evolutionary Transitions in Early Life: A Public Goods Approach · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 67 Lelliott, A.D., A Survey of Visitors’ Experiences of Human Origins at the Cradle of Humankind, South Africa· · · · · · · · · · · · · · 68 Looy, C., The End-Permian Biotic Crisis: Why Plants Matter · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 69 Reed, K., Hominin Evolution and Habitat: The Importance of Analytical Scale · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·
    [Show full text]
  • Variability of the Parietal Foramen and the Evolution of the Pineal Eye in South African Permo-Triassic Eutheriodont Therapsids
    The sixth sense in mammalian forerunners: Variability of the parietal foramen and the evolution of the pineal eye in South African Permo-Triassic eutheriodont therapsids JULIEN BENOIT, FERNANDO ABDALA, PAUL R. MANGER, and BRUCE S. RUBIDGE Benoit, J., Abdala, F., Manger, P.R., and Rubidge, B.S. 2016. The sixth sense in mammalian forerunners: Variability of the parietal foramen and the evolution of the pineal eye in South African Permo-Triassic eutheriodont therapsids. Acta Palaeontologica Polonica 61 (4): 777–789. In some extant ectotherms, the third eye (or pineal eye) is a photosensitive organ located in the parietal foramen on the midline of the skull roof. The pineal eye sends information regarding exposure to sunlight to the pineal complex, a region of the brain devoted to the regulation of body temperature, reproductive synchrony, and biological rhythms. The parietal foramen is absent in mammals but present in most of the closest extinct relatives of mammals, the Therapsida. A broad ranging survey of the occurrence and size of the parietal foramen in different South African therapsid taxa demonstrates that through time the parietal foramen tends, in a convergent manner, to become smaller and is absent more frequently in eutherocephalians (Akidnognathiidae, Whaitsiidae, and Baurioidea) and non-mammaliaform eucynodonts. Among the latter, the Probainognathia, the lineage leading to mammaliaforms, are the only one to achieve the complete loss of the parietal foramen. These results suggest a gradual and convergent loss of the photoreceptive function of the pineal organ and degeneration of the third eye. Given the role of the pineal organ to achieve fine-tuned thermoregulation in ecto- therms (i.e., “cold-blooded” vertebrates), the gradual loss of the parietal foramen through time in the Karoo stratigraphic succession may be correlated with the transition from a mesothermic metabolism to a high metabolic rate (endothermy) in mammalian ancestry.
    [Show full text]
  • Rehabilitation of National Route R61 (Section 3, Km 24.2 to Km 75) Between Cradock and Tarkastad, Eastern Cape
    PALAEONTOLOGICAL HERITAGE STUDY: COMBINED DESKTOP AND FIELD-BASED ASSESSMENT Rehabilitation of National Route R61 (Section 3, km 24.2 to km 75) between Cradock and Tarkastad, Eastern Cape John E. Almond PhD (Cantab.) Natura Viva cc, PO Box 12410 Mill Street, Cape Town 8010, RSA [email protected] February 2013 1. SUMMARY The South African National Roads Agency Limited (SANRAL) is proposing to rehabilitate Section 3 of the National Route R61 (km 24.2 to km 75) between Cradock and Tarkastad, Eastern Cape. The project involves widening of the roadway and of all stormwater structures along the route. Road material is to be sourced from five new or existing borrow pits and one hard rock quarry. A Phase 1 palaeontological heritage assessment for the road project has been commissioned by Arcus GIBB (Pty) Ltd in accordance with the requirements of the National Heritage Resources Act (Act 25 of 1999). Section 3 of the R61 traverses the outcrop area of continental sedimentary rocks of the Upper Beaufort Group (Tarkastad Subgroup, Karoo Supergroup) of Early to Middle Triassic age. These are cut and baked by numerous dolerite intrusions of the Karoo Dolerite Suite of Early Jurassic age. Towards Cradock (Graaff-Reinet and Middelburg 1: 250 000 sheet areas) the sedimentary bedrocks belong to the sandstone-dominated Katberg Formation that was deposited in arid braided fluvial settings following the catastrophic end-Permian mass extinction event. Further east towards Tarkastad (Queenstown and King William’s Town 1: 250 000 sheet areas) the sedimentary bedrocks are assigned to the slightly younger Burgersdorp Formation comprising recessive-weathering reddish mudrocks and braided river channel sandstones.
    [Show full text]
  • Triassic Pentadactyl Tracks from the Los Menucos Group
    Triassic pentadactyl tracks from the Los Menucos Group (Río Negro province, Patagonia Argentina): possible constraints on the autopodial posture of Gondwanan trackmakers Paolo Citton1,2, Ignacio Díaz-Martínez1,2, Silvina de Valais1,2 and Carlos Cónsole-Gonella1,3 1 Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina 2 Instituto de Investigación en Paleobiología y Geología (IIPG), Universidad Nacional de Río Negro, General Roca, Argentina 3 Instituto Superior de Correlación Geológica (INSUGEO), Universidad Nacional de Tucumán, Tucumán, Argentina ABSTRACT The Los Menucos locality in Patagonia, Argentina, bears a well-known ichnofauna mostly documented by small therapsid footprints. Within this ichnofauna, large pentadactyl footprints are also represented but to date were relatively underinvestigated. These footprints are here analyzed and discussed based on palaeobiological indications (i.e., trackmaker identification). High resolution digital photogrammetry method was performed to achieve a more objective representation of footprint three-dimensional morphologies. The footprints under study are compared with Pentasauropus from the Upper Triassic lower Elliot Formation (Stormberg Group) of the Karoo Basin (Lesotho, southern Africa). Some track features suggest a therapsid-grade synapsid as the potential trackmaker, to be sought among anomodont dicynodonts (probably Kannemeyeriiformes). While the interpretation of limb posture in the producer of Pentasauropus tracks from the Los Menucos locality
    [Show full text]
  • Introduction to the Tetrapod Biozonation of the Karoo Supergroup
    See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/342446203 Introduction to the tetrapod biozonation of the Karoo Supergroup Article in South African Journal of Geology · June 2020 DOI: 10.25131/sajg.123.0009 CITATIONS READS 0 50 4 authors, including: Bruce S Rubidge Michael O. Day University of the Witwatersrand Natural History Museum, London 244 PUBLICATIONS 5,724 CITATIONS 45 PUBLICATIONS 385 CITATIONS SEE PROFILE SEE PROFILE Jennifer Botha National Museum Bloemfontein 82 PUBLICATIONS 2,162 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: Permo-Triassic Mass Extinction View project Permo-Triassic palaeoecology of southern Africa View project All content following this page was uploaded by Michael O. Day on 24 August 2020. The user has requested enhancement of the downloaded file. R.M.H. SMITH, B.S. RUBIDGE, M.O. DAY AND J. BOTHA Introduction to the tetrapod biozonation of the Karoo Supergroup R.M.H. Smith Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, 2050 South Africa Karoo Palaeontology, Iziko South African Museum, P.O. Box 61, Cape Town, 8000, South Africa e-mail: [email protected] B.S. Rubidge Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg 2050, South Africa e-mail: [email protected] M.O. Day Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg 2050, South Africa e-mail: [email protected] J. Botha National Museum, P.O. Box 266, Bloemfontein, 9300, South Africa Department of Zoology and Entomology, University of the Free State, 9300, South Africa e-mail: [email protected] © 2020 Geological Society of South Africa.
    [Show full text]
  • Stepwise Shifts Underlie Evolutionary Trends in Morphological Complexity of the Mammalian Vertebral Column
    ARTICLE https://doi.org/10.1038/s41467-019-13026-3 OPEN Stepwise shifts underlie evolutionary trends in morphological complexity of the mammalian vertebral column Katrina E. Jones 1*, Kenneth D. Angielczyk2 & Stephanie E. Pierce 1* A fundamental concept in evolutionary biology is that life tends to become more complex through geologic time, but empirical examples of this phenomenon are controversial. One 1234567890():,; debate is whether increasing complexity is the result of random variations, or if there are evolutionary processes which actively drive its acquisition, and if these processes act uni- formly across clades. The mammalian vertebral column provides an opportunity to test these hypotheses because it is composed of serially-repeating vertebrae for which complexity can be readily measured. Here we test seven competing hypotheses for the evolution of vertebral complexity by incorporating fossil data from the mammal stem lineage into evolutionary models. Based on these data, we reject Brownian motion (a random walk) and uniform increasing trends in favor of stepwise shifts for explaining increasing complexity. We hypothesize that increased aerobic capacity in non-mammalian cynodonts may have pro- vided impetus for increasing vertebral complexity in mammals. 1 Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA. 2 Integrative Research Center, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, IL 60605-2496, USA. *email: katrinajones@fas. harvard.edu; [email protected] NATURE COMMUNICATIONS | (2019)10:5071 | https://doi.org/10.1038/s41467-019-13026-3 | www.nature.com/naturecommunications 1 ARTICLE NATURE COMMUNICATIONS | https://doi.org/10.1038/s41467-019-13026-3 nderstanding the remarkable complexity of living organ- system, a concept that is key to our intuitive understanding of Uisms is one of the most fundamental and alluring topics in complexity.
    [Show full text]
  • A NEW SKELETON of the THEROCEPHALIAN SYNAPSID OLIVIEROSUCHUS PARRINGTONI from the LOWER TRIASSIC SOUTH AFRICAN KAROO BASIN by JENNIFER BOTHA-BRINK* and SEAN P
    [Palaeontology, Vol. 54, Part 3, 2011, pp. 591–606] A NEW SKELETON OF THE THEROCEPHALIAN SYNAPSID OLIVIEROSUCHUS PARRINGTONI FROM THE LOWER TRIASSIC SOUTH AFRICAN KAROO BASIN by JENNIFER BOTHA-BRINK* and SEAN P. MODESTOà *Karoo Palaeontology, National Museum, PO Box 266, Bloemfontein 9300, South Africa Department of Zoology and Entomology, University of the Free State, Bloemfontein 9300, South Africa; e-mail: [email protected] àDepartment of Biology, Cape Breton University, Sydney, NS B1P 6L2, Canada; e-mail: [email protected] Typescript received 10 June 2009; accepted in revised form 6 July 2010 Abstract: We provide a redescription of the therocephalian topterygoid instead of a narrow shaft, the presence of promi- therapsid Olivierosuchus parringtoni based on a new specimen nent pterygoid tuberosities and a narrow, elongated tabular. recovered from the Lower Triassic Lystrosaurus Assemblage A reappraisal of Lower Triassic therocephalian biostratigra- Zone of South Africa and discuss the biostratigraphic impli- phy reveals that most of these taxa are restricted to the lower- cations of Lower Triassic South African therocephalians. The most part of the Lystrosaurus Assemblage Zone revealing a new specimen comprises a skull and articulated anterior por- high diversity, whereafter the diversity decreases dramatically tion of the postcranial skeleton. Olivierosuchus parringtoni in the middle of the zone. However, despite their scarcity in can be distinguished from its akidnognathid relatives, Promo- the middle and upper Lystrosaurus Assemblage
    [Show full text]