Bryozoanand crustacean from Fruitland Formation (UpperGretaceous) ol New Mexico by Barry S. Kues,Department of Geology, University of New Mexico, Albuquerque, NM Introduction land badlandsin the NE 1/4NE1/4 SEl/+ sec. The bryozoan specimendescribed below The Fruitland Formation of northwest New 3'1,,T. 24 N., R. 13 W (University of New was colleited fromthis localityduring a brief Mexico is a widely exposedcoal-bearing se- Mexico locality BUNM 77-25), 0.8 km (0.5 paleontologicalsurvey (Froehlichand Kues, quenceof predominantly nonmarine deltaic mi) south of the Bisti Trading Post site (now 1977), and exact stratigraphic information is facies,deposited along the westernshoreline abandoned)and about 40 m (132ft) east of not available. It came from a gray shale con- of the Midcontinent epeiric sea as it re- NM-371, San fuan County (Fig. 1). At this taining complete in situ Tereilinashells and gressednortheastward out of New Mexico locality a thin but persistentcoal bed (Coal carbonizedplant matter, probably a few me- nearthe end of Late Cretaceoustime (Fassett D of Hutchinson, 1981)is exposed low on ters below the coal bed. and Hinds, 1971;Hutchinson, 1981).The biota the ridge. This coal is overlain by a dark-gray, Hutchinson (1981)measured a stratigra- of the Fruitland is extremely diverse. It in- organic-richshale that becauseof decrease phic section a short distance south of this cludes 24 species of nonmarine mollusks in organic content becomes lighter in color iocality and placed the coal bed about 30 m (Stanton, 191,6),65 species of vertebrates upsection.This shale,in turn, is overlainby (99 ft) above the baseof the Fruitland and 50 (sharks,rays, bony fish, amphibians,turtles, an extensivechannel sand deposit consisting m (165ft) below the Fruitland-Kirtland con- lizards,snakes, crocodilians, dinosaurs, and of white. moderatelv well indurated quartz- tact. Deposition of the Fruitland occurred mammals;see list in Lucas,1981), and more ose sandstonewith lenses of gray-brown, aboveand lateral to the shoreline sandstones than 80 speciesof plants (combinedtotal for highly indurated, concretionary sandstone of the Pictured Cliffs Sandstone as the "Pic- Fruitland and lower part of Kirtland Shale; locallycontaining low-angle crossbeds (Figs. tured Cliffs Sea" retreated to the northeast Tidwell and others, 1981;Robison and others, 2, 3). At the base of the channel sandstone (Fassettand Hinds, 1971;Flores and Erpen- 1982).Although earlier work on the Fruitland is a transition zone consistingof thin, hori- beck, 1981).The lower part of the Fruitland biota proceeded sporadically, paleontologi- zontallybedded white sandstoneIayers that has been recognizedas consistingof coastal cal investigations have intensified in the past are interbedded with carbonaceouslaminae swamp, estuarine,and delta plain deposits six years. Recentcollecting efforts have been and blocky to pebbly greenish-gray clay- (Fassettand Hinds, 1.971;Hutchinson, 1981). primarily devotedto the areabetween Hunter stones. This transition zone yielded a rich Hutchinson (1981)assigned the lower 20 m and De-Na-Zin washes("Bisti Badlands"area) collectionof vertebratebone fragments,scales, (66 ft) of the Fruitland to an estuarine facies, and south of Split Lip Flats ("FossilForest" and teeth, in addition to Tereilina(Bivalvia) and Hartman (1981)noted that brackishen- area) as a result of attempts to survey and shell fragments and the crab claw described vironments extend as much as 36 m (119f0 study exposuresthat may be affectedby coal below. Examinationof surface-collectedand above the base of the Fruitland, with a sig- strip mining in the near future. The purpose screenedvertebrate specimens revealed had- nificant increase in diversity of freshwater of this paper is to record the first occurrence rosaur teeth, turtle shell fragments, croco- mollusks above this level. of Bryozoa and second occurrence of Crus- dilian scutes and teeth, gar scales,amiid Bryozoa taceain the Fruitland and to discuss their (bowfin) teeth, small, rounded teeth tenta- paleoenvironmental implications. tively referred to the pycnodont holostean Thebryozoan colony (Figs. 4, 5) was found In this paper, UNM refers to the University fish Anomaeodus,and ray teeth (Myledaphus attached to a fragment of the posterior area of New Mexico paleontology collections and SP.)' of a ceratopsian skull. The colony is a thin USNM to the U.S. National Museum pa- leontology collections. Location and stratigraphic setting The fossils described herein were collected from the north side of a low ridge of Fruit- FIGURE l-Location of bryozoan-crustaceanlo- cality fi) N sEc 31, T. 24 N., R. 13 W., San Juan Countv, New Mexico. Each side of sec. 32 eouals FIGURE 2-View of Fruitland exposuresin area of bryozoan-crustaceanlocality, looking west. Vehicle 1.5kd (1 mi). is parked along NMJ71. X marks level of "Coal D." August 1983 New MexicoGeology encrustation approximately 75 cm, in areaon east. Alternatively, the bryozoan might have served or identified as such by vertebrate the ledge below the occipital condyle, ex- been a permanent inhabitant of brackish paleontologists.Though bryozoans are cer- tends over the broken edgeof the ledge,and waters during Fruitland deposition. Possi- tainly not common in the Fruitland, addi- coversseveral cracks in the bone. Growth of bly, because most studies of Fruitland pa- tional specimens will probably be found in the zoarium thus occurred after fragmenta- ieontology have concentrated on fhe the brackish-water facies of the formation as tion of the skull and after transpor'iof the vertebrates, bryozoans have not been ob- study of Fruitland faunas proceeds. rF fragments.The bryozoanspecimen was sub- mitted to Dr. Alan Cheetham, Smithsonian Institution, who identified it as Conopeum? sp.,a membraniporoidanascan cheilostome. Cheetham noted (written communication, 1981)that zooecialmorphology is well pre- served and includes distinct gymnocvsts, crenulatecryptocysts, and smali6asesof dis- tal spines.These features and the sizeof the present on the Fruitland specimen, which consistsmainly of late multilamellar growth. The skull fragment with attachedbiyozoan has been donated to the SmithsonianInsti- tution and bearsthe cataloguenumber USNM 297027. Although most modern cheilostomebry- ozoanslive in water of normal marine salin- ity, somegenera are typically found in brackish water. The Recentspecies Conopeum seurati lives in environmentsless saline than 20Too and can toleratesalinities as low as 7%o(Rv- land, 7970,p. 71).The presenceof Conopeum? sp. in a certainly nonmarine facies of the Fruitland strongly suggests that Cretaceous FIGURE.3-Bryozoan-crustacean locality, showing white channel sandstone eroded into small pinna- :]:t, i"g unde-rlying dark shale. Fossil-rich transition zone between sandstone and shale is at highest thin dark band, at shoulder level of figure to left. bryozoan approached that of a modern Con- opeumspecies, the Fruitland specimen could have settled and grown in estuarine waters of only slight salinity. - To assessmore precisely the position of bryozoans in the estuarine communities of the Fruitland Formation is difficult at pres- ent..Thisis the first report of their presence in the Fruitland, and bryozoans are un- known in the marine sediments of the pic- tured Cliffs Sandstone. Specimens of membraniporoidand pyripoid bryozoans have been observed attiihed to inoceramid and ammonoid shells in the offshore marine deposits of the Lewis Shale in the eastern San Juan Basin (W. A. Cobban, personal c_ommunication,1983). Two explanationsof the bryozoan'spresence in the Fruitland are possible, and additional specimensfrom the Fruitland and equivalent marine units will be needed to determine which is probably the correctone. As the Lewis Shalewas de- FIGURE 4-Occipital c91dy]e of ceratopsiandinosaur (USNM 297021).Bryozoan colony is below con- environment many kilometers to the north- dyle, around ledge to left of cm scale. Nao Mexico Geology August 1983 FIGURE S-Close view of part of Conopeum?sp. colonv x 2. B A FIGURE 7-Teredinn sp.; A, UNM 69M, ventral view, showing articllated. prirnary valves (top) and long calcareoustube t^hatextends posteriorly from valves; B, UNM 6943, distorted specimen showing thi&ened calcitic area at posterioi end of tube (bottom of specimen). Fragments of this part.of tube were abundant in microvertebrate lag deposits in transition zone. Scaleis same for both specimens. Fruitland specimen and lack the prominent localities and levels in the Fruitland may pro- rounded teeth. Previously, Armstrong-Zie- vide a reliable basis for indicating brackish gler (1980,p. 30) reported unidentified crab environments and for distinguishing brack- claws from a locality northwest of Bisti, on ish from freshwater facies. the Navajo Reservation. As with cheilostome bryozoans, most modern crabs live in fully marine environ- ments, but some do prefer brackish condi- tions. A few modem specieslive in conditions of very low salinity (Pearseand Gunter, 1952), and groups of a dozen or more shells are and this may have been true of the Fruitland ofterifouird in their vertically oriented life B crab as well. No crabs of this fype have been positions in the Fruitland. Complete shells but have not ptevi- crabcheliped (UNM 6749);A, reported from the Lewis Shale or Pictured ire relatively common FIGURE6-Partial lived inner surface,x 2; B, outer surface,x 2. Cliffs Sandstone,so, until evidence to the ously beenfigured. Teredinaapparently contrary appears,this crab is consideredto