American Museum Published by the American Museum of Natural History Central Park West at 79Th Street, New York, N.Y

American Museum Published by the American Museum of Natural History Central Park West at 79Th Street, New York, N.Y

NovitatesAMERICAN MUSEUM PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK, N.Y. 10024 Number 2930, 32 pp., 13 figs., 2 tables February 6, 1989 Evolution of the Aeluroid Carnivora: Significance of the Ventral Promontorial Process of the Petrosal, and the Origin of Basicranial Patterns in the Living Families ROBERT M. HUNT, JR.' CONTENTS Abstract ........................................... 1 Introduction ........................................... 2 Acknowledgments ........................................... 3 Abbreviations ........................................... 3 Petrosal Form in the Living Aeluroid Families ........................5............ The Auditory Region in the Oldest Known Aeluroid Carnivorans ........ ........... 7 The Stenoplesictine Concept ........................ ................... 12 A New Stenoplesictine Basicranium from Quercy ................. ................ 14 Petrosal Form in the Living Aeluroid Nandinia binotata ............ ............... 15 The Proailurine Basicranium and Petrosal ........................................ 21 Origin of the Living Aeluroid Families ........................................... 23 Conclusions ........................................... 29 References ........................................... 30 ABSTRACT In studies of carnivoran phylogeny, the config- useful in tracing modem lineages to their first ap- uration and ontogenetic development of the au- pearances in the mid-Cenozoic. Pre-Oligocene ditory bulla enclosing the middle ear have been camivorans, however, lack preserved bullae and I Research Associate, Department of Vertebrate Paleontology, American Museum of Natural History; Curator, State Museum and Department of Geology, University of Nebraska, Lincoln, Neb. 68588. Copyright © American Museum of Natural History 1989 ISSN 0003-0082 / Price $3.70 2 AMERICAN MUSEUM NOVITATES NO. 2930 have been difficult to relate to later Cenozoic indicates that the form of Nandinia's petrosal groups. The carnivoran petrosal bone, because of closely approximates the petrosals of Oligocene its durability both in intact skulls and as an iso- stenoplesictine aeluroids from the Quercy fissues lated element, can be tracked through Cenozoic ofFrance. Stenoplesictines are the oldest generally time, and can supply new information on lineage acknowledged aeluroids represented by basicra- continuity through its geometry and spatial rela- nial remains. The strong anatomical correspon- tionships. dence shared by the Quercy stenoplesictine basi- Aeluroid carnivorans are united by a petrosal crania with the basicranium of Nandinia reflects of characteristic shape, distinguished by a ventral the plesiomorphic auditory structure of these promontorial process buttressing the lateral mar- groups. However, relative to stenoplesictines, gin of the basioccipital. The configuration of the Nandinia's auditory region is more primitive in process is highly uniform in most living aeluroids the structure ofthe auditory bulla and surrounding (viverrids, herpestids, hyaenids) but has been sup- basicranium; its basicranium is arrested at a pre- pressed in modem felids by encroachment of an Oligocene structural grade, and is representative inflated auditory bulla. Ancestral proailurine fe- of the projected ancestral aeluroid morphotype. lids, however, retain the process. Survey ofthe aeluroid fossil record suggests that Among living aeluroids, the African palm civet the modem aeluroid basicranial and bulla patterns Nandinia binotata is distinguished by a somewhat developed in the mid- to late Miocene, and were differently configured ventral promontorial pro- well established by the Plio-Pleistocene. Prior to cess, which is more posteriorly situated and ro- the mid-Miocene, an array of archaic basicranial bust. Comparison with fossil aeluroid basicrania patterns characterized the aeluroid Carnivora. INTRODUCTION An improved understanding of the evo- and details of its structure are only conjec- lution ofthe mammalian order Carnivora has tural at the present time. The nature of au- resulted from detailed anatomical study of ditory bullae in early Tertiary carnivorans the auditory region in both living and extinct may be eventually clarified by study of re- lineages (Flower, 1869; Hough, 1948; Ted- cently discovered fully articulated skeletons ford, 1976). Ontogenetic elements forming ofEocene carnivorans from Messel for which the auditory bulla join to create unique mor- little postmortem disturbance is inferred phopatterns diagnostic of particular lineages (Springhorn, 1980, 1982, 1985). (Hunt, 1974a). Such lineages are most com- However, in the interim, a useful insight monly identified at the family level within comes from another quarter: identification of the order, and can be traced in some cases the small Holarctic Oligocene carnivoran Pa- into the Oligocene. laeogale as a relict lineage of the early Ter- The auditory bulla has not been found in tiary viverravids (Hunt, 1974b; see also Flynn pre-Oligocene fossil carnivoran basicrania, and Galiano, 1982) demonstrates the struc- and only rarely occurs in the extinct creodont ture ofthe auditory bulla in a member ofone carnivores (Mellett, 1977). This situation of the principal early Tertiary carnivoran seems to result from (a) a record of very few families (Viverravidae). Although the den- well-preserved skulls ofPaleocene and Eocene tition of Palaeogale exhibits aeluroid affini- Carnivora in paleontological collections; (b) ties (Flynn and Galiano, 1982), its unique probable loose attachment ofthe bulla to the single-chambered fully ossified bulla is not skull; (c) lack of ossification of some or all typically aeluroid, and suggests that early bulla elements. Tertiary viverravids probably did not possess Based on present knowledge of taxonomic the derived bulla configuration of the living distribution and morphology of the ontoge- aeluroid families. This conclusion raises sev- netic elements making up the auditory bulla eral important questions concerning the liv- in post-Eocene camivorans, we might rea- ing aeluroid groups: When did the modern sonably predict that Paleocene and Eocene bulla patterns develop? Can additional de- carnivorans possessed a multipart bulla rived traits be identified that unite the aelu- (formed by an ectotympanic and one or more roid families in addition to bulla configura- entotympanics) as in living forms. However, tion? such a bulla has yet to be discovered intact, Modern aeluroid bulla patterns appear in 1 989 HUNT: AELUROID CARNIVORA 3 the mid- to late Miocene, based on a review plesictine skulls (M1723, M1381) discussed of aeluroid basicranial patterns in the fossil in this report; to Dr. Guy Musser, American record, identified and summarized in this re- Museum of Natural History, New York, for port. From this conclusion it follows that one permission to study aeluroid carnivorans in should not expect to find aeluroid basicranial the Department of Mammalogy; to Drs. patterns typical of the living families in the Richard Tedford and Michael Novacek, early Tertiary. American Museum of Natural History, for Consequently, in the tracing of carnivoran access to fossil carnivorans in the Depart- lineages, it would be useful to identify other ment of Vertebrate Paleontology; and to Dr. features ofthe skeleton that can be employed Patricia Freeman for loan of carnivorans in as reliable anatomical markers in lieu of the the Zoology Division, University of Nebras- dentition and bulla. The basicranium ofCar- ka State Museum, Lincoln. I am grateful to nivora has been a fertile source of data for G. de Beaumont and Qiu Zhanxiang for use- phylogenetic studies in the past, so it is not ful discussions on fossil aeluroid carnivorans. surprising that a fresh examination of this My thanks to Marc Marcuson for preparation part ofthe skull, particularly the auditory re- of figures 7, 8, and 13. For review of the gion, might provide new insights. My recent manuscript, I appreciate the comments of work indicates that the form of the petrosal Harold Bryant, Patricia Freeman, Neil Land- bone has potential as a phyletic marker. In man, Bruce MacFadden, R. T. Schuh, and the Aeluroidea, a characteristic configuration Richard Tedford. of the petrosal promontorium can be iden- tified (Hunt, 1987: 44). It is found in repre- ABBREVIATIONS sentative species of all the major aeluroid families: A alisphenoid viverrids, herpestids, hyaenids, AC anterior carotid foramen primitive felids, and in the living primitive BO basioccipital aeluroid Nandinia. In addition, it appears that BS basisphenoid the petrosal configuration of aeluroids may Ca anterior crus of ectotympanic be responsible for the unusual double-cham- E caudal entotympanic bered arrangement of their auditory bulla, a EO exoccipital structural peculiarity that has been difficult F facet for ectotympanic on petrosal to explain. FR round window To demonstrate this, I first illustrate and G gonial discuss petrosal form in representative mem- H hypoglossal (condyloid) foramen bers of the living aeluroid groups; then de- ICA internal carotid artery L middle lacerate foramen scribe the structural parallels in petrosal and M mastoid basicranium between the oldest generally ac- P petrosal knowledged aeluroids (stenoplesictines) and PC posterior carotid foramen the living African aeluroid Nandinia, with PLF posterior lacerate foramen particular attention given to a recently iden- PP paroccipital process of exoccipital tified stenoplesictine basicranium

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