Enigmatic Osteology in Miocene odontocete rostra suggests periostitis

MARINE MAMMAL SCIENCE, 26(2): 381–394 (April 2010)C© 2009 by the Society for Marine MammalogyDOI: 10.1111/j.1748-7692.2009.00342.x

Enigmatic osteology in Miocene odontocete rostrasuggests periostitis

JENNIFER M. GERHOLDT1∗STEPHEN J. GODFREY∗∗

Department of Paleontology,Calvert Marine Museum,

P. O. Box 97, Solomons, Maryland 20688, U.S.A.E-mail: ∗[email protected],

∗∗[email protected]

ABSTRACT

Eight Miocene odontocete partial rostra (six specimens from the ChesapeakeGroup of Maryland, one from the Chesapeake Group of Virginia, and another fromthe Hawthorn Group of Florida) exhibit periostitis, of unknown etiology, character-ized by proliferative bone growth. Periostitis is an inflammation of the periosteumsecondary to a predisposing event such as a fracture or infection. Computed tomog-raphy reveals that the lesions are limited to the premaxillae and that they becameprogressively swollen and gnarled as evidenced by the onion-like layering withinthe deformity. The level of maturity and degree of organization of the periostitis in-dicates that it likely developed over a period of months or years in these individuals.Given this length of time, these pathologies seem not to have been life-threateningdespite the gross size and shape of most of these periosteal reactions.

The fossils range in age from about 11 to 15 million yr and all eight rostraappear to be derived from the same, but as yet unnamed or unrecognized speciesof odontocete. The family from which these odontocetes derive remains unknown.Un-deformed rostra attributed to this species have not been identified, which opensthe possibility that “abnormal” was the new normal for this species of odontocete.

Key words: odontocete, periostitis, fossil, pathology, rostrum, deformity, Miocene,Chesapeake Group, Hawthorn Group, Calvert Cliffs.

The field of paleopathology investigates how disease processes evidence themselvesin the fossil record. It is now widely recognized that disease manifestations are rela-tively stable through time and that human pathologies appear directly comparable tothose seen in prehistoric species (Rothschild and Martin 1993, Tanke and Rothschild2002).

Multifarious disease conditions and injuries to the rostrum and mandibles incetaceans are known. A few examples include a broken mandible in a stranded

1Current Address: Global Forest & Trade Network North America, World Wildlife Fund, 1250 24thStreet NW, Washington, DC 20037, U.S.A.[Author’s affiliation updated after online published date of Sept 7, 2009]

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striped dolphin, Stenella coeruleoalba (Gales 1992), an unusual rostral curvature ina mature La Plata dolphin, Pontoporia blainvillei, as a result of incidental captures(Brownell 1989), bone lesions in the tucuxi, Sotalia fluviatilis, as a consequence ofentanglement in fishing nets (Ramos et al. 2001), a healed fracture and osteolyticlesions in a male Cuvier’s beaked whale, Ziphius cavirostris (Ketten 2005), and threecases of mandibular disease in the sperm whale, Physeter macrocephalus (Murie 1865,Thompson 1868). Examples among mysticetes include a fractured mandible andassociated oral lesions in a bowhead whale, Balaena mysticetus (Philo et al. 1990),and fractured skulls and mandibles in the North Atlantic right whale, Eubalaenaglacialis, the unfortunate result of vessel-whale collisions (Campbell-Malone 2007,Campbell-Malone et al. 2008).

The literature becomes scant, however, when one focuses on rostral and mandibu-lar paleopathologies in extinct cetaceans. Bjotvedt (1977) described mandibularlesions in some prehistoric Aleutian cetaceans, and Dawson (1996) and Dawson andGottfried (2002) described chronic osteomyelitis in the right mandible of a Miocenekentriodontid delphinoid from Calvert Cliffs, Hadrodelphis calvertense.

The purpose of this article is to report on the presence of idiopathic periostitis(i.e., periostitis of unknown cause or origin) in eight fossilized odontocete partialrostra from the Miocene of Maryland, Virginia, and Florida. Periostitis is a chronicinflammation of the periosteum secondary to a predisposing event such as a fracture,infection, or inflammatory processes in response to trauma (Ortner and Putschar1985, Messe and Sebastianelli 1996, McWhinney et al. 2001, Mann and Hunt2005). These deformed rostral segments are also noteworthy because they appear torepresent the remains of an unknown or unrecognized odontocete species.

Institutional Abbreviations

AMNH = American Museum of Natural History, New York, NY; CMM-V =Calvert Marine Museum vertebrate collection, Solomons, MD; USNM = NationalMuseum of Natural History, the Smithsonian Institution, Washington, D.C.

GEOLOGICAL AND PALEOENVIRONMENTAL SETTING

Seven of the eight fossilized odontocete partial rostra described herein derivefrom the Miocene epoch Calvert and Choptank formations (two of the formationswithin the Chesapeake Group). Two of these rostra were collected in situ from seacliffs along Chesapeake Bay, Maryland; CMM-V-2663 from Bed 13 of the CalvertFormation and USNM 412124 from the Choptank Formation (Bed unknown). Thesediments comprising Bed 13 of the Calvert Formation are approximately 15 million-yr old, whereas the Choptank Formation along Calvert Cliffs ranges in age fromapproximately 11 to 13 million yr (Gottfried et al. 1994, Kidwell and Kelly 1998).The geological and paleoenvironmental settings within these Miocene formationsin Maryland and Virginia have been described by Shattuck (1904), Kidwell (1984,1989), Vogt and Eshelman (1987), Ward and Powars (1989), Ward (1992), Gottfriedet al. (1994), Kidwell and Kelly (1998), and Ward and Andrews (2008). The entirelyextinct cetacean fauna within the Chesapeake Group comprises a diverse assemblageof approximately 30 species of both odontocetes and mysticetes (Shattuck 1904,Gottfried et al. 1994, Godfrey and Barnes 2008).

GERHOLDT AND GODFREY: MIOCENE ODONTOCETE OSTEOLOGY 383

CMM-V-3949 was recovered from sediments approximately 11 million-yr oldderived from the Bone Valley Member of the Peace River Formation. The geologicaland paleoenvironmental settings within the Miocene Hawthorn Group of Floridahave been described in detail by Scott (1988), Hulbert (2001), Scott et al. (2001),and Petuch and Roberts (2007). The diverse cetacean fauna has been reviewed mostrecently by Morgan (1994) and Hulbert (2001).

SYSTEMATIC PALEONTOLOGY

MAMMALIA Linnaeus, 1758CETACEA Brisson, 1762ODONTOCETI Flower, 1867 Incertae sedisA total of eight specimens (CMM-V-2663, CMM-V-3929, CMM-V-3949, USNM

412120, USNM 412124, USNM 425487, USNM 452910, and USNM 534014) arecurrently known to exhibit this rostral deformity caused by proliferative bone. Themost informative specimens are figured and described in detail. To view the internalanatomy of these fossilized rostra, computed tomography technology (i.e., CT scans)was employed obviating the need for destructive histological sectioning. These scansreveal that in life, with or without the periosteal bony lesions, the premaxillaefused dorsomedially to enclose the mesorostral canal. Externally, above the fusedpremaxillae and mesorostral canal, the premaxillae are smoothly or grotesquelyswollen. On the basis of their shared morphology, there is no reason to think thatthey are not all derived from the same species, but given the fragmentary nature ofthese unusual finds it is possible that they represent more than one closely relatedspecies.

DESCRIPTIONS

CMM-V-2663

CMM-V-2663 (Fig. 1) consists of a 28.9 cm-long section of an odontocete rostrum.The partial rostrum is composed of grotesquely swollen premaxillae to which undis-torted maxillae are fused. Short anterior and posterior segments of non-pathologicalbone frame the pathology. In a left lateral view (Fig. 1B), the anterior end of thesegment is curved slightly ventrally. This curvature may have been caused by theoriginating trauma or the resulting periostitis. The break at about the midpoint inthe length of the rostral section occurred postmortem. The two segments consti-tuting CMM-V-2663 were collected separately and reunited years later. M. Melvincollected the tooth-bearing portion on 25 February 1996 in Bed 13 of the CalvertFormation between Western Shores and Kenwood Beach, Calvert County, Maryland.W. Douglass collected the posterior moiety preserving only premaxillae on or aboutthe same date from the same location. These two segments are presumed to be derivedfrom approximately the midpoint in the length of the rostrum.

The premaxillae are fused along their entire length. Areas of localized swelling arepronounced. Dorsally (Fig. 1A) the sinuous suture between the premaxillae is clearlyvisible. Vascular furrows course over much of the surface of the premaxillae but aremore prominent on the right side. Apposition of woven secondary bone layers ontothe original rostral surface can be seen over most of both premaxillae, resulting in ahighly porous and irregularly pitted outer layer. Individual CT scan images (Fig. 1C,


Figure 1. CMM-V-2663 in A. Dorsal; B. Left lateral; C. 1–3, CT scans through the rostrumas indicated by the line segment above each CT image; and D. Ventral view. Scale bar equals10 cm. Abbreviations: alv = alveolus; mes = mesorostral canal; Mx = maxilla; Pmx =premaxilla.

1–3) evidence the onion-like layers of secondary bone growth over the originallyslender rostrum. Fusion of the premaxillae dorsally encloses the mesorostral canalbelow the lesions. In life, the mesorostral canal would have held the mesorostralcartilage. Ventrally on either side of the mesorostral canal the premaxillae are suturedto the maxillae. These tongue-and-groove sutures are visible posteriorly where themaxillae are not preserved (Fig. 1D).

The maxillae do not appear to have been affected by the pathology. They arepreserved only below the anterior section of the pathological premaxillae. Twenty-two and 21 complete subcircular alveoli are preserved in the left and right maxillae,respectively. Each alveolus is nearly 4.5 mm long and 3.5 mm wide. Center to center,ipsilateral (i.e., same side) alveoli are 6 mm apart. The contralateral (i.e., opposingside) maxillary tooth rows are extremely close together; anterior and posterior alveoliare only 7 mm and 7.5 mm apart, respectively. Two well-formed teeth were found insitu. The tooth in the left maxilla was removed from the posterior-most alveolus (thatstill preserves its medial margin) to be photographed and described (Fig. 2B). Theother tooth occupies the ninth complete right alveolus from the front (Fig. 1B, D).Both teeth possess a simple conical crown and hatchet-shaped root. Immediatelyabove the enameled crown in a labial or lingual view of the tooth, the root exhibitsslightly swollen shoulders. Beyond the wide shoulders, the root narrows ever soslightly before flaring to form the blade of the hatched-shaped root (Fig. 2B). Theanteroposteriorly elongate blade of the root curls slightly laterally. In an anterior orposterior view of the tooth, the root is never wider than the base of the enameledcrown, and in this view, the root thins away from the crown.


Figure 2. A. A single transverse CT scan image through USNM 412124 (Fig. 3C, 3)illustrating how greatly enlarged the premaxillae became above the prepathological dorsaloutline of the rostrum. The thick black line outlines the prepathological transverse outlineof the premaxillae. B. A left maxillary tooth from CMM-V-2663 in labial (lateral) view (leftis toward the front of the rostrum). Scale bar equals 10 mm for B. Abbreviation: Pmx =premaxilla.

USNM 412124

B. Kent collected USNM 412124 (Fig. 3) in April 1987 from the ChoptankFormation, approximately 2 km north of Matoaka Cottages, Long Beach, CalvertCounty, Maryland. It consists of a 19.1 cm-long rostral section that is broken atboth ends. As in CMM-V-2663, a postmortem break occurred at about the segment’smidpoint. USNM 412124 is formed almost entirely by unevenly swollen and fusedpremaxillae. CT scan images (Fig. 2A, 3C, 1–4) reveal the original outline of the ros-tral surface under layers of pathological bone. The anterior and posterior ends of thisjaw segment taper to what are assumed to be more normal proportions. Dorsally, thesuture between the premaxillae is pronounced and at times conspicuously misaligned(Fig. 3A). Where the outer layer of lamellar bone has not been abraded postmortem,vascular furrows course over its surface. These furrows originate along the ventralmaxillary margin of the premaxillae. Five enlarged foramina are also visible on the


Figure 3. USNM 412124 in A. Dorsal; B. Left lateral; C. 1–4, CT scans through therostrum as indicated by the line segment above each CT image; and D. Ventral view. Scale barequals 10 cm. Abbreviations: mes = mesorostral canal; Mx = maxilla; Pmx = premaxilla.

outer surface of the premaxillae. The pathological fibrous woven bone is pitted andporous, exposed thusly as a result of postmortem abrasion.

As seen in CMM-V-2663 (Fig. 1), ventrally, ridges and furrows on either side ofthe dorsally enclosed mesorostral canal mark where the maxillae were sutured to thepremaxillae (Fig. 3D). In lateral (Fig. 3B) and ventral (Fig. 3D) views, the tooth-bearing portions of the maxillae are preserved only anteriorly by strap-like segmentsof their lateral walls. No alveoli are preserved. Also in lateral view, it is at about themidpoint in the length of these maxillary strips that the premaxilla appears to bedeflected ventrally. This deflection might mark a premaxillary fracture that did notappear to impact the adjacent maxilla.

USNM 425487

USNM 425487 (Fig. 4) was collected as beach float by G. Fowler on or about24 October 1987 from the beach north of Rocky Point, Calvert County, Maryland.


Figure 4. USNM 425487 in A. Dorsal; B. Left lateral; C. 1–3, CT scans through therostrum as indicated by the line segment above each CT image; and D. Ventral view. Scalebar equals 10 cm. Abbreviations: mes = mesorostral canal; Pmx = premaxilla.

The specimen is believed to be locally derived from the Choptank Formation thatis exposed in the bay cliffs adjacent to the beach at Rocky Point. USNM 425487 isa 12.2 cm-long rostral segment consisting of fused premaxillae. It is more heavilychafed than the previously described specimens (Fig. 4A, B). Much of the outerlamellar bone is missing, presumably eroded during the time this specimen tumbledabout in the surf prior to collection.

CT scans show that the originally slender and gracile premaxillae were conspic-uously enlarged (Fig. 4C, 1–3). Regions of localized swelling on the dorsal side ofthe rostrum are present. The furrowed suture between the premaxillae is angleddiagonally across the dorsal surface of the rostral segment (Fig. 4A). The maxillaeare not preserved, although remnants of the elongate sutures in the premaxillae oneither side of the mesorostral canal are (Fig. 4D).


Figure 5. USNM 412120 in A. Dorsal; B. Left lateral; C. CT scan through the rostrumas indicated by the line segment above the CT image; and D. Ventral view. Scale bar equals10 cm. Abbreviations: mes = mesorostral canal; Pmx = premaxilla.

USNM 412120

C. Smith collected USNM 412120 (Fig. 5) as beach float at Matoaka Cottages, St.Leonard, Calvert County, Maryland. Although the fossil was not found in situ, it wasalmost certainly derived from the cliffs adjacent to the beach. The coloring of thefossil suggests it originated from the Choptank Formation, the sediments of whichcomprise most of the cliff exposure along this length of Calvert Cliffs.

USNM 412120 consists of a 12.4 cm-long tapering rostral section of fused premax-illae. Both anterior and posterior ends are broken. The straight-line suture betweenthe premaxillae is visible only on the dorsal side of the partial rostrum (Fig. 5A). Theanterior two-thirds of the specimen appear normal, whereas the posterior one-third isprogressively enlarged, preserving a fracture-callus-like swelling. Reticulating vas-cular furrows that originate from the suture between premaxillae and maxillae arevisible over the enlarged pathology (Fig. 5B). A trough-like suture along the fulllength of the premaxillae on either side of the mesorostral canal held the maxillae inlife (Fig. 5D). The CT scan shown in Figure 5C illustrates that remnants of the pre-pathological premaxillae are preserved within the specimen. Notice that the sidesof the pre-pathological premaxillae are present, but that the pathology destroyed


the pre-pathological dorsal margins of the premaxillae as evidenced by the darkenedcentral area.

CMM-V-3929

CMM-V-3929 is an 8.9 cm-long segment of fused premaxillae that closely resem-bles USNM 412120 in the expression of the pathology that it preserves. This shortsegment of odontocete rostrum was collected as beach float by R. Hazen on 4 April2008 at Western Shores, Calvert County, Maryland.

CMM-V-3949

CMM-V-3949 is a 12.7 cm-long segment of premaxillae; swollen, fused, andspindle-shaped. This short segment of odontocete rostrum was collected in April2008 by H. Murdoch in Hardee County at the South Fort Meade Mine from theBone Valley Member of the Peace River Formation (Hawthorn Group, Florida:the Bone Valley Member was formerly the Bone Valley Formation of Matson andClapp 1909). MacFadden and Webb (1982), Webb and Crissinger (1983), and Scott(1988) recorded that the Bone Valley Member of the Peace River Formation extendsfrom latest Early Miocene (latest Burdigalian) to the Early Pliocene (Zanclean).CMM-V-3949 was collected from an overburden pile in the mine. This otherwiseunremarkable specimen is of particular interest because it demonstrates that this kindof rostral lesion, in probably the same kind of odontocete, was reasonably widespreadgeographically.

USNM 452910

USNM 452910 is a 10.4 cm-long segment of fused rostral premaxillae from CalvertCliffs, Maryland (additional collection and locality information are unknown). Dor-sally, the suture between the premaxillae is more pronounced posteriorly. Most ofthe premaxillary surface is smooth and uniformly swollen over its entire surface.The vascular furrows that characterize the other specimens are not present. Theirabsence may reflect postmortem abrasion or healing of the pathology prior to death.Ventrally, a mesorostral canal is well-defined.

USNM 534014

USNM 534014 is a 17.8 cm-long segment of fused premaxillae. The variouslypreserved and gnarled dorsal surface marked with vascular furrows is in stark contrastto the smoothly finished internal premaxillary surface of the mesorostral canal. USNM534014 was collected by M. Culliman as float at Stratford Beach, WestmorelandCounty, Virginia.

DISCUSSION

Generally, inflammatory periosteal bone deposited over a long period of timetends to be irregular and of variable thickness as seen in the rostra described herein.According to Messe and Sebastianelli (1996), periosteal reactions in humans typicallymanifest themselves radiographically 4 to 6 wk after the initial injury. The level of


maturity and degree of organization of the periostitis in these odontocetes indicatesthat it likely developed over a period of months or years.

Unfortunately, in these odontocetes the etiology of this pathology is unknown.Furthermore, there is no explanation as to why the lesions are seemingly limited onlyto the premaxillae. Presumably, the localization of the pathology was the result of aninfection or injury, such as an abrasion wound or a fracture only to the premaxillae(the size and shape of the maxillae, where preserved, does not seem to have beenaltered by the hyperostotic growth of the premaxillae). USNM 412124 (Fig. 3B)is the only specimen that hints that a fracture (to its left premaxilla) may havecontributed to the initial onset of periostitis. It is tempting to suggest that becausethe rostrum in these odontocetes was so gracile, it was more susceptible to thiskind of injury and resulting lesion. In the extant slender-snouted La Plata dolphin,Pontoporia blainvillei, it is possible for the premaxillae to fracture in life without themaxillae being damaged. Two skulls of P. blainvillei (USNM 501163 and 550555)exhibit fractured premaxillae but undamaged maxillae. However, none of the over300 La Plata dolphin skulls in the collections of the USNM and the AMNH exhibitany sign of rostral periostitis, although other pathologies exist. No known group ofextant odontocetes exhibits this kind of rostral pathology and therefore they do nothelp in resolving the origin of these deformities.

In humans, syphilitic skin ulcers (chancre) can provoke periosteal reaction onbones that tend to be near the skin surface (Ortner and Putschar 1985). Syphilis isa venereal disease caused by a spirochetal bacterium. Although it is not known ifthe periostitis in these cetaceans was the result of a sexually transmitted pathogen,it is worth keeping in mind that a bacterially induced skin ulcer on the rostrum ofthese odontocetes may have caused these lesions. A virulent micro-organismal originfor these rostral deformities seems at least as likely (if not more so) as their originresulting from the same kind of physical trauma.

With so many individuals exhibiting this kind of deformity, we became intriguedby the possibility that a hyperostotic rostrum characterized this currently unnamedor unrecognized odontocete. As this project, progressed and more similarly afflictedspecimens came to light, what was initially considered abnormal became normal.That a genetically mediated deformity or pathology could characterize a significantpercentage of individuals within a species has already been documented. Wang andRothschild (1992) describe a multiple hereditary osteochondroma in the Oligocenecanid Hesperocyon. Was this species of long-snouted odontocete genetically predis-posed to develop a gnarled and thickened rostrum? As tempting as it is to claimthe enlarged premaxillae as an autapomorphy characterizing a new taxon, the urgewill be resisted pending the discovery of more complete specimens providing con-firmatory evidence one way or another. Ironically, it would appear as though theproliferative periosteal bone growth contributed to the preservation of an otherwisedelicate structure in a few representatives of a species that is otherwise unknown.

That these odontocetes probably lived with this condition for long periods of timeindicates that their afflictions did not precipitate mortality. There is no question thatinjuries to the mandibles and teeth can lead to limitations in cetaceans on food intakeand an overall deterioration of health and untimely death (Bjotvedt 1977, Philoet al. 1990, Erb et al. 1996). Chronic secondary bone formations have been shownto be debilitating and can become extremely painful, interfering with an animal’sability to capture and consume prey (Dawson and Gottfried 2002). It is not knownto what extent, if any, these hyperostoses hampered the ability of these cetaceans tofind, capture, and consume prey.


As evidenced by the CT scans, the non-pathological morphology of the rostra sug-gests they are all derived from the same species of Miocene odontocete. In comparingthe non-pathological portions of the maxillae and teeth in CMM-V-2663 with everyother named odontocete in the Chesapeake Group, no match was found. In CMM-V-2663, opposing (i.e., contralateral) maxillary tooth rows are more closely spacedthan in any other Miocene odontocete from Maryland or Virginia. The closely setand parallel tooth-rows do not appear to be an artifact of the deformity. The bilateralproximity of the parallel maxillary tooth rows, along with the size and spacing of thealveoli, are similar to the configuration seen in the extant La Plata dolphin, Pontoporiablainvillei (Pontoporiidae) (Flower 1869, Barnes 1985, Brownell 1989, Ramos et al.2000). The simple conical crown and hatchet-shaped root of the teeth in CMM-V-2663 also suggests pontoporiid affinities, although hatchet-shaped roots are alsopresent in the Yangtze River dolphin, Lipotes vexillifer (Lipotidae, USNM 218293)(Flower 1869, Muizon 1984, fig. 16–17; Barnes 1985, Brownell 1989, Ramos et al.2000) and the extant Ganges River Dolphin, Platanista gangetica (Platanistidae). Thedeformed rostra also share with P. gangetica very close approximation of the right andleft tooth rows.

The only odontocete with very closely set tooth rows from the Hawthorn Group inFlorida is the poorly known Goniodelphis hudsoni (Allen 1941, Morgan 1994, Hulbert2001, fig. 17.9b). Both the rostrum and mandibles are laterally compressed as arethe triangle-shaped roots of these simple conical-crowned teeth (Hulbert 2001).

Of the pathological rostra, USNM 412120, 412124, and 425487 had been re-ported as being derived from ziphiids (Gottfried et al. 1994). At the time thisassignment was made, the only specimen that preserves maxillary alveoli and teeth(CMM-V-2663) had not yet been discovered. It is understandable that Gottfried et al.(1994) attributed the former specimens to the Ziphiidae because in several respectsthey resemble the normal “swollen” rostra of some Miocene beaked whales (Lambert2005). In addition to which, CT scans through the rostra described herein reveal asupravomerine canal formed over the mesorostral gutter by fusion of the dorsomediallips of the premaxillae, as is also seen in some Miocene ziphiids including Messapice-tus and Ziphirostrum (Bianucci et al. 1992, 1994; Lambert 2005; Fuller and Godfrey2007). However, even with the discovery of CMM-V-2663 (the specimen preservingthe teeth), we cannot presently rule out the possibility that these deformed rostraderive from a slender-snouted small-toothed ziphiid because a primitive member ofthis family with a full dentition consisting of many small teeth awaits description.Clearly, a resolution of the taxonomic affinities of these enigmatic odontocete rostramust await further discoveries of more complete skulls.

ACKNOWLEDGMENTS

We are grateful to all who collected and donated the pathological rostral segments tothe USNM and the CMM. We are also indebted to B. Frohlich (USNM) for CT scanningthe rostra. D. Hunt (USNM), D. Ortner (USNM), and M. Kricun generously identified thepathology, and lengthy discussion with them and B. Rothschild helped us along the way. D.Bohaska (USNM), J. Mead (USNM), C. Potter (USNM), and E. Westwig (AMNH) kindlyprovided liberal access to the collections of both fossil and extant odontocetes in their care.J. Pojeta (USNM) welcomed us to his lab so that we could whiten the fossils with sublimedammonium chloride. We are also indebted to D. Steere, M. Rosen, and P. Lasker (USNMLibrary) for their assistance in tracking down pertinent literature.


Reviews by B. Rothschild and three anonymous reviewers for MMS improved the finaldraft. We are also indebted to D. J. Boness (Editor, MMS) and D. Domning (Associate Editor,MMS) for shepherding this paper along.

J.M.G. completed this study as a research intern at the Calvert Marine Museum. Fundingfor her internship came from The Clarissa and Lincoln Dryden Endowment for Paleontologyat the Calvert Marine Museum. This publication would not have been possible withoutadditional funding from the Board of Calvert County Commissioners and the Citizens ofCalvert County, MD.

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Received: 1 April 2009Accepted: 9 June 2009

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Enigmatic Osteology in Miocene odontocete rostra suggests periostitis

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