A Giant Presbyornis (Aves, Anseriformes) And Other Birds From The Paleocene Aquia Formation Of Maryland And Virginia

7 Pages·1994·2 MB·English

by  S L Olson

PROC. BIOL. SOC. WASH.
107(3), 1994, pp. 429-435
A GIANT PRESBYORNIS (AVES: ANSERIFORMES)
AND OTHER BIRDS FROM THE PALEOCENE AQUIA
FORMATION OF MARYLAND AND VIRGINIA
Storrs L. Olson
Abstract.—Presbyornis isoni, new species, is described from a humerus and
an alarphalanx from marine sediments ofthe late PaleoceneAquia Formation
in Maryland. About the size ofthe smallest living species ofcrane (Gruidae),
itwasmuchlargerthananypreviouslyknownmemberofthePresbyomithidae.
Other fragmentary bird remains from the Aquia Formation are noted, several
ofwhich may be referable to the suborder Phaethontes ofthe Pelecaniformes.
Additional Paleocene birds from eastern North America occur in the Hor-
nerstown Formation of New Jersey, which is now considered to be Danian
(early Paleocene) in age, rather than late Cretaceous.
The marine sediments ofthe Aquia For- Gemx% Presbyornis '^QXmovQ, 1926
mationcropoutintheChesapeakeBayarea Presbyornis isoni, new species
ofMaryland and Virginia. They are oflate Figs. 1, 2
Paleocene (Landenian) age and overlie the
Holotype.—heft humerus lacking proxi-
Brightseat Formation (Danian), between
mal third, collections ofthe Department of
which there is a disconformity representing Paleobiology, National Museum ofNatural
about 3.6 million years, a period of time USNM
History, Smithsonian Institution,
approximately equivalent to that ofthe ex-
294116. Collected in March 1993 by Ron-
posed Aquia Formation (Hazel 1969). The
ald M. A. Ison.
Aquia is divided into an upper Paspotansa
Member and a lower Piscataway Member, Typelocality.—Maryland, CharlesCoun-
the latter having sometimes been designat- ty, east bank of the Potomac River, from
the area designated as Bluebanks, south of
ed in earlier literature as the Piscataway
LiverpoolPointandnorthofDouglasPoint
Formation or Piscataway Indurated Marl
Member ofthe "early Eocene." These sed- (Widewater Quadrangle, USGS 7.5 minute
series).
iments accumulated in a pelagic environ-
Horizon and age.—Near the base ofthe
ment,welloffshore,andarereasonablypro-
Upper Paleocene (Landenian), Aquia For-
ductive of vertebrate fossils, e.g., turtles
mation,PiscatawayMember.Thespecimen
(Weems 1988), but so farhaveyielded very
A camefromnearthebaseofthebluffexposed
few bird remains. recently collected hu-
merusisthelargestandmostdiagnosticavi- atthetypelocality,whichisprobablyupper
nannoplanktonzoneNP5,butpossiblylow-
an fossil yet discovered in the Aquia For-
mation, As it merits description, I have ceromNm.P)6. (OLnaurtehle Ms.calBeyboefll,BerUgSgGreSn, epterasl..
takentheopportunitytoreviewthefewoth-
(1985), the age would be somewhere be-
er avian fossils found so far in the same
tween 61 and 62 million years.
strata.
Measurements ofholotype(mm).—Distal
width, 23.3; depth through radial condyle,
Class Aves 12.9; greatest diameter ofbrachial depres-
Order Anseriformes sion, 8.8; width and depth of shaft at ap-
Family Presbyomithidae Wetmore, 1926 proximate midpoint, 10.8 x 8.2.
430 PROCEEDINGSOFTHEBIOLOGICALSOCIETYOFWASHINGTON
C
B
Fig. 1. Humeri in palmar view (A-C) and phalanx 1 ofmajor alar digit (D-E) of Presbyomithidae: A,
Presbyornisisoninewspecies,holotype(USNM294116);B, Telmabatesantiquus(AMNH3170);C,Presbyornis
pervetus (cast, USNM 483163); D, Presbyornis isoni new species, paratype (USNM 294117); E, Presbyornis
USNM
pervetus(cast, 483164). All figuresnatural size.
Paratype.—IjqH phalanx 1 ofmajor alar size, therearenodiscemabledifferencesbe-
digit, abraded along the posterior edge, tweenP. isoniand P. pervetus, savethatthe
USNM
2941 17. Collected in June 1984 by olecranal fossa appears less distinct in the
EugeneHartstein atthe same localityas the former, which may be a size-related factor.
holotype. Discussion.—Presbyornisis a remarkable
Measurements of paratype (mm).— bird that exemplifies an early stage in the
Length, 40.6; greatest diameterofproximal evolution of the Anseriformes, combining
articulation, 9.5. a long-legged, shorebird-like body with the
Etymology.—Named in honorofthe col- head of a duck (Olson & Feduccia 1980).
lector, Ronald M. A. Ison, an enthusiastic Presbyornis pervetus occurs abundantly in
amateur paleontologist. lacustrinedepositsoftheearlyEoceneGreen
Diagnosis.—M-wch larger than Presbyor- River Formation of Wyoming, Colorado,
nis pervetus Wetmore, 1926, or any other and Utah, and a slightly smaller form is
known members ofthe family. Apart from found in the Paleocene ofUtah and Mon-
.
VOLUME 107, NUMBER 3 431
Fig. 2. Left humeri ofPresbyornis: (A, C, E) P. isoni new species, holotype (USNM 294116); (B, D, F) P.
pervetus(part ofUCMP 136541). A-B, palmar view; C-D, anconal view; E-F, distal view. Specimens coated
withammoniumchloride. 1.5x
golia (Olson 1985a:171). The contempora- Stockholm, pers. comm.). Thetype species,
neousgenus Telmabates, fromPatagonia, is T. antiquus, was considerably larger than
very similar to Presbyornis and was syn- Presbyornispervetus.
onymized with that genus by Feduccia & Presbyornis isoni was much larger than
McGrew (1974). Further study, however, either. To put the relative differences in
hasshownthatthelimbproportionsofTel- terms ofmodem analogs forsize, Presbyor-
mabatesdiffer sufficiently from Presbyornis nispervetuswould have been about the size
to meritretentionofthegenus(PerEricson, ofthe largest species ofBurhinus, the Bush
Swedish Museum of Natural History, Stone-curlew, B. magnirostris, ofAustralia.
432 PROCEEDINGSOFTHEBIOLOGICALSOCIETYOFWASHINGTON
Telmabates antiquus was about the size of vergent ofthe Pelecaniformes, relegated to
a Limpkin, Aramus guarauna, whereas a separate suborder Phaethontes. The first
Presbyornis isoni would have been the size fossil assigned to the family was Prophae-
ofa Demoiselle Crane, Anthropoides virgo. thon shrubsolei Andrews (1899), known
It is possible, given its much larger size, from a skull, mandible, andpartial postcra-
thatthe feeding adaptations ofP. isonimay nial skeleton from the early Eocene (Ypre-
have been different from those ofP. perve- sian) London Clay ofEngland. Harrison &
tus, and that were the entire skeleton avail- Walker (1976) restudied the specimen and
ableitmightbeassignedtoadifferentgenus. created a new order and family for it, only
As it is, however, there is no distinction the latter being justified, however (Olson
whatever to be made between these taxa 1985a). Theonlyotherfossilmemberofthe
except on size. Phaethontes is Heliadornis ashbyi Olson
The considerable assemblage of birds (1985b),knownfromthreeassociatedbones
knownfromtheHomerstownFormationof from the Middle Miocene (Langhian) Cal-
New Jersey (Olson & Parris 1987) are now vert Formation ofMaryland, whichwasre-
believed to be Danian (early Paleocene) ferred to the Phaethontidae.
ratherthan latest Cretaceous in age (see be-
low), and are older than P. isoni. Most of Family Prophaethontidae
&
these birds were referred to the "form fam- Harrison Walker, 1976
ily"Graculavidae,whichsharessimilarities Genus Prophaethon Andrews, 1899
withthePresbyomithidae.Presbyornisisoni Prophaethonl sp.
was larger than any ofthese species except
Material examined.—Distal end ofright
Laornisedvardsianus,whichwasmuchlarg- USNM m
er than P. isoni. The species in the Hor- humerus, 483158. Collected 1
fromtop ofchalky shellbandofAquiaFor-
nerstown most similar to P. isoni is Ana- mation at Capital Beltway and Central Av-
talavis rex, which was a much smaller bird
enue, Prince Georges, County, Maryland
in which the brachial depression is longer, (LanhamQuadrangle,USGS 7.5 minutese-
narrower, andnotasdeep, andinwhichthe
ries), by Calvin F. Allison, Jr. in 1973. Dis-
shaftappearstohavebeenrelativelyshorter tal width, 7.6 mm.
and more curved.
Right coracoid lacking part ofthe acro-
Although the alar phalanx referred to P.
coracoid and the lateral process ofthe ster-
miseonnti,iistsnositzeaapnadrtoivceurlaalrllysidmiialganroisttyitcoetlhee- nRaulhoenfdf,atUaSrNoMad4c8u3t1o5n9.InCdoillaencHteedabdyHTi.ghB-.
sameelementinPresbyornismakesithighly way,about200mnorthofPiscatawayCreek,
unlikely that it would belong to some other Prince Georges County, Maryland(Piscata-
familyaltogether. Thattwoelementsofthis way Quadrangle, USGS 7.5 minute series).
presumed land bird were discovered at the "About 10-12 feet above road." This is ev-
same site, the sediments ofwhich were de- idently the same as the type locality ofthe
paroesistceadrcwee,lslugogfefssthsotrheatantdhewyhmearye bhiarvdebcoonmees fossil turtle Catapleura ruhoffi (Weems
1988). Length to internal distal angle 28.5
from the same individual, despite having mm.
been collected years apart.
Remarks.—ThQ humerus is extremely
similarto that in modem tropicbirds ofthe
Order Pelecaniformes Sharpe
genusPhaethon, practicallythe onlynotice-
Suborder Phaethontes
able difference being the indistinctness of
The modem tropicbirds (Phaethontidae, the external tricipital groove, but this may
Phaethon), are the most primitive and di- be an artifact as the specimen is consider-
VOLUME 107, NUMBER 3 433
ablyworn inthis area. Itcomes from abird Abradeddistalendoflefttibiotarsuslack-
much smaller than any living tropicbird, ing internal condyle, USNM 2941 18. Col-
about the size ofa Common Tern, Sterna lected from "Top Gully" of Aquia For-
hirundo, and thus much smaller than Pro- mation at the Hampton Mall Site, Central
phaethon shrubsolei or Heliadornis ashbyi, Avenue near Capital Beltway, Prince
although the distal end of the humerus is GeorgesCounty, Maryland(LanhamQuad-
unknown in either ofthose species. rangle, USGS 7.5 minute series), in 1984
The coracoid from the Aquia was com- by Eugene Hartstein. Depth through exter-
pared directly to that from the holotype of nal condyle, 3.7 mm. Thisis from a species
P. shrubsolei and is very similar in overall small enough to be of comparable size to
shape and proportions, but much smaller. Prophaethonl sp., but it bears no resem-
At the sternal end, the specimens are lack- blance to the tibiotarsus in Phaethon. It is
ingcomplementary portions and hence can similar, however, to that element in the ge-
scarcely be compared. Both have a shallow nus Palaeotringa, from the Homerstown
&
scapular facet. It is apparent that in the Formation (Olson Parris 1987), though
smaller species the procoracoid process muchsmallerthananyofitsknownspecies.
would not have projected as much anteri-
orly, and the procoracoid foramen is more Size 2
stemallysituated(i.e.,fartherfromthescap-
ular facet). Also the triossial groove in the Proximal halfofphalanx 1 ofmajor alar
procoracoid is deeper in Prophaethon. digiUt,SUNSMNM 483161. Same collection data
The Aquia coracoid is small and if not as 483159. Greatest diameter of
from a bird the same size as represented by proximal articulation, 5.0 mm.
thehumerus,wouldbefromaslightlylarger Proximal shaft ofleft humerus including
USNM
individualorspecies.Thesetwobonesseem pectoral crest, 483162. The label
to be sufficiently diagnostic to be referred with this specimen, in Alexander Wet-
to the Phaethontes, but they are assigned more's hand, says only "Piscataway For-
only provisionally to the Prophaethontidae mation, Virginia, fromTedRuhoff." Width
on the basis oftheir age. and depth of shaft just distal to pectoral
crest, 4.0 x 5.0 mm.
Aves Incertae Sedis These two specimens come from a bird
the size ofmodem Phaethon lepturus, and
Size 1 such little morphology as remains on them
isactuallyquite similartothatofPhaethon,
USNM
Distalthirdofrightulna, 483160. so that they might well be from the same
SamecollectiondataasthecoracoidofPro- species and perhaps belong among the
phaethon"? sp. mentioned above. Depth of Phaethontes.
distalendthroughexternalcondyle,4.4mm.
Thisspecimenisfromasmallbird, possibly
Size 3
smaller than Prophaethonl sp. Its mor-
phology is quite unlike the distinctive con- Proximal end of right carpometacarpus
dition in modem Phaethon, in which the NewJerseyStateMuseum 13532. Collected
carpaltubercleisdevelopedasastronghook, as floatatBelvedereBeach, PotomacRiver,
andismoresimilartothatinProcellariifor- KingGeorge County, Virginia(Passapatan-
mes, but as we do not know what the ulna zy Quadrangle, USGS 7.5 minute series),
looked like in ancient Phaethontes, it can- 27 Dec 1985 byEugeneHartstein. Proximal
not be ruled out that this fossil belongs in depth through alular metacarpal, 13.3 mm.
that group. Although not found in situ, the specimen is
434 PROCEEDINGSOFTHEBIOLOGICALSOCIETYOFWASHINGTON
most probably Paleocene as the exposures vey will have none of this and place the
at this locality are entirely a green glauco- outcropping portions ofthe basal Homers-
niticsandy marl ofthePaspotansaMember town in nannoplankton zone NP 3 (Laurel
ofthe Aquia Formation. The bone comes M. Bybell, USGS, pers. comm.), which is
from a bird slightly larger than Phaethon Danian, Lower Paleocene, between about
rubricauda, the largest modem tropicbird, 64 and 65 million years in age (Berggren et
but differs considerably from that genus. It al. 1985). A Cretaceous assignment may
has some resemblance to the carpometa- haveariseneitherthroughreworkingofMe-
carpus in the Sulidae but again is quite dif- sozoic macrofossils into the younger sedi-
ferent, though it could still belong to some ments, or through the persistence of oth-
member ofthe Pelecaniformes. erwise Mesozoic taxa into the earliest
Theageofthe "Cretaceous"birds ofNew Tertiary.
Jersey.—TherecordofPaleocenebirdsfrom Althoughitmakesnogreatdifferenceone
marinedepositsisquitescantyandthespec- way oranotheras faras avian evolutionary
imens discussed above would probably be history is concerned, as birds with some of
the only ones known from North America the same general morphological attributes
wereitnotforthefactthatthefairlydiverse existed before and after the Homerstown
avifauna derived from the marine sedi- Formation, the refinements brought about
ments ofthebasal Homerstown Formation by modem microfossil analysis would ap-
in New Jersey, long considered to be late pearto necessitatetheNewJersey birds be-
Cretaceous(Maastrichtian)inage,areprob- ingrelinquishedaspartofMesozoichistory.
ably Paleocene as well. These fossil birds
have received attention since the early Acknowledgments
1870's, when many ofthe taxa were origi-
nally described by O. C. Marsh. The fauna I thank Ron Ison and Eugene Hartstein,
hasbeenrecentlyrevisedbyOlson &Parris for collecting and donating the fossils of
Presbyornis described here. Laurel M. By-
(1987).
The age of the basal Homerstown has bell, Thomas Gibson, and Robert Weems
been, andstillis, ahighlycontentiousissue. of the U.S. Geological Survey provided
The birds from here were originallyregard- stratigraphic information, maps, and ref-
ed as Cretaceous (Marsh 1870, 1872), then erences. For lending various fossils I am
Paleocene (Wetmore 1930), then Creta- gratefultoCharlotteHolton,AmericanMu-
ceous (Baird 1967). Weems (1988) cites seum of Natural History, New York
some of the more recent literature giving (AMNH); Howard Hutchison, Museum of
evidence for the basal Homerstown being Paleontology, University of California,
Paleocene, but still notes some dissention. Berkeley (UCMP); David C. Parris, New
There seems to be consensus thatthe up- JerseyStateMuseum,Trenton(NJSM);and
perHomerstown is definitely Paleocene, so Cyril Walker, British Museum (Natural
that ifthe basal part were Cretaceous, then History). The photographs are by Victor E.
the K/T boundary would have to lie within Krantz. I thank Robert Weems for com-
theHomerstown,which,iftrue,shouldhave ments on the manuscript and Mark Ror-
ence for curatorial assistance.
attracted international attention. I get the
impression that local pride may be in-
volved, with the New Jersey contingent Literature Cited
holding out for a Cretaceous attribution,
Andrews,C. W. 1899. Ontheremainsofanewbird
Mesozoic fossils presumably being more from the London Clay ofSheppey.—Proceed-
glamorous than Cenozoic ones. Neverthe- ingsoftheZoological Society ofLondon 1899:
less, personnel ofthe U.S. Geological Sur- 776-785.
VOLUME NUMBER
107, 3 435
Baird, D. 1967. Age offossil birds from the green- . 1985b. A newgenus oftropicbird (Pelecan-
sandsofNewJersey.—Auk 84:260-262. iformes: Phaethontidae)from the MiddleMio-
Berggren, W. A., D. V. Kent,J. J. Flynn, &J. A. Van cene Calvert Formation of Maryland.—Pro-
Couvering. 1985. Cenozoicgeochronology.— ceedingsoftheBiologicalSocietyofWashington
GeologicalSocietyofAmericaBulletin96:1407- 98:851-855.
1418. , & A. Feduccia. 1980. Presbyornis and the
Feduccia,A.,&P.O.McGrew. 1974. Aflamingolike origin of the Anseriformes (Aves: Charadrio-
waderfrom the Eocene ofWyoming.—Contri- morphae).-Smithsonian Contributions to Zo-
butionstoGeologyUniversityofWyoming 13: ology 323:1-24.
49-61. , &D. C. Parris. 1987. The Cretaceousbirds
Harrison, C. J. O., and C. A. Walker. 1976. A re- ofNewJersey.—Smithsonian Contributionsto
appraisal of Prophaethon shrubsolei Andrews Paleobiology63:1-22.
(Aves).—Bulletin ofthe British Museum (Nat- Weems,R.E. 1988. PaleoceneturtlesfromtheAquia
ural History), Geology 27:1-30. andBrightseatFormations,withadiscussionof
Hazel,J. E. 1969. Faunalevidenceforan unconfor- their bearing on sea turtle evolution and phy-
mitybetweenthePaleoceneBrightseatandAquia logeny.—Proceedings ofthe Biological Society
Formations (Maryland and Virginia).—U.S. ofWashington 101:109-145.
Geological Survey Professional Paper 650-C: Wetmore,A. 1926. FossilbirdsfromtheGreenRiver
C58-C65. deposits ofeastern Utah.—Annals ofthe Car-
Marsh,O.C. 1870. Noticeofsomefossilbirdsfrom negie Museum 16:391^02.
the Cretaceous and Tertiary formations ofthe . 1930. The age ofthe supposed Cretaceous
UnitedStates.—AmericanJournalofScienceser birdsfrom NewJersey. Auk47:186-188.
2., 49:205-217.
. 1872. Preliminarydescriptionof//eiperor«w Department ofVertebrate Zoology, Na-
regalis, with notices offour other new species tional Museum ofNatural History, Smith-
ofCretaceousbirds.—AmericanJournalofSci-
ence ser 3., 3:360-365. sonianInstitution,Washington,D.C. 20560,
Olson, S. L. 1985a. The fossil record ofbirds. Pp. U.S.A.
79-238 in D. Famer, J. King, and K. Parkes,
eds.AvianBiology,volume8.AcademicPress,
NewYork.