Jacisin and Hopkins—Fossil newts from the Oligocene of Oregon


the work of Thormahlen (1984) and Smith et al. (1998), the location of this specimen coincides with the Trail Crossing flora, which to date has produced Acer, Alnus, Fagus, and Quercus fossils from ashy, tan to yellow, massive to stratified, highly silicified lacustrine siltstone and sandstone beds. These beds are consistent with the temperate, hardwood-dominated Bridge Creek flora of the Oligocene. The fossils from Gray Butte are


between 32–33Ma because the overlying alkali-olivine basalt is 40Ar/39Ar-dated at 32.49 ± 0.30 Ma, and the lithology of the Gray Butte area aligns with the middle Big Basin Member of the western facies of the John Day Formation.


Materials and methods


Systematic paleontology and comparative morphology.—For this study, we re-examined all the previously described speci- mens of fossil salamanders fromthe Oligocene ofOregon, as well as a number of previously undescribed specimens and the skele- tons of several extant salamandrids. This included comparing them to modern salamander taxa in order to understand caudate


evolutionary relationships during a period of climatic cooling, floral transition, and perhaps increased seasonality during the early Oligocene in the Pacific Northwest of North America. The specimens are in collections at the University of Oregon Museum of Natural and Cultural History (UOMNH), University of California-Berkeley Museum of Paleontology (UCMP), and John Day Fossil Beds National Monument (JODA).


Table 1 contains a list of the specimens examined. We


examined skeletons and isolated bones of eight Taricha granulosa, a single Taricha sierrae, seven Taricha torosa,12 Taricha rivularis, and four Notophthalmus viridescens, in addition to the fossils of five T. oligocenica,12 T. lindoei, and one fossil identified to genus Taricha. For all examined specimens, we recorded morphologic details of the scapulocoracoid, phalangeal count, and vertebral column, especially the atlas and trunk vertebrae, since these features have been noted as useful for diagnosing fossil salamanders in the past (Estes, 1981; Holman, 2006). We paid special attention to details of the skull when possible because it is rare to find a complete or mostly complete salamander skull in the fossil record, where skull fragments and postcrania (particularly trunk vertebrae) are much more common than articulated specimens. The systematic descriptions provide details of the morphology of these structures. We coded several of these details into the phylogenetic analysis as characters. Because each fossil preserves different areas of the


skeleton, establishing useful measurements is a complex task. For example, the vertebral measurements used in Tihen (1974) are difficult to apply to fossils that are articulated skeletons, impressions, or flat (as are so many of the relatively complete salamander fossils). Instead, this study uses a variety of measurements, as applied by Good and Wake (1992) to the morphometrics of the genus Rhyacotriton and by Kuchta (2007) to the morphometrics of T. torosa and T. sierra, whenever possible. While the small sample size and limited variety of age classes for fossils make it unlikely that we can perform a morphometric analysis in the manner of Good andWake (1992) and Kuchta (2007), these measurements are still useful for determining body proportions and predicting the size of


T. torosa T. sierrae


Notophthalmus viridescens


715


Table 1. List of specimens with collection numbers. Dagger symbol (†) indi- cates extinct taxa.


Taxon T. lindoei† Specimen #


Taricha oligocenica† UOMNH F-5405, UOMNH F-30648, UOMNH F-36412, UOMNH F-55196, UOMNH F-59812 A-B,


Taricha sp.† T. granulosa


T. rivularis


UOMNH F-35553, UOMNH F-59813, UOMNH F-30616, UOMNH F-109709, UOMNH F-109710, UOMNH F-110577, UOMNH F-111395 A-B, UOMNH F-37883 A-B, JODA 10429 A-B, JODA 1230, UCMP 137464, UCMP 137466


UCMP 137465


UCMP 118876, UCMVZ 67956, UCMVZ 67969, UCMVZ 218168, UCMVZ 218169, UCMVZ 218170, UCMVZ 218171, UCMVZ 218172


UCMP 81746, UCMVZ 78190, UCMVZ 111544, UCMVZ 111546, UCMVZ 111548, UCMVZ 68232, UCMVZ 68233, UCMVZ 68234, UCMVZ 68235, UCMVZ 68236, UCMVZ 68237, UCMVZ 78191


UCMP 81747, UCMVZ 4480, UCMVZ 68179, UCMVZ 68180, UCMVZ 68181, UCMVZ 68182, UCMVZ 129891 UCMVZ 129892


UCMP 117050, UCMP 118873, UCMP 118874, UCMVZ 185290


individual specimens. These measurements include snout-vent length (SVL), tail length (TL), snout-gular length (SG), head width (HW), eye width (EW), distance between the eyes (E-E), distance from eye to nostril (E-N), axilla-groin length (AG), trunk width (TW), forelimb length (FLL), hind limb length (HLL), and foot length (FL). Weused digital calipers or a metric ruler at the millimeter scale for all attainable measurements for each fossil. Some of these measurements (SVL, SG, and AG) use soft-tissue reference points (Good and Wake, 1992; Kuchta, 2007), and we adjust these to use osteological landmarks that represent corresponding measurements for fossil taxa. Here, the anterior edge of the premaxilla to the posterior edge of the pelvic girdle is SVL, the anterior edge of the premaxilla to the anterior portion of the atlas is SG, and the length of the trunk between the forelimb and the hind limb is AG. We took all University of Oregon (UO) and John Day


Fossil Beds National Monument (JODA) fossil salamander photos with a Nikon D-90 at a focal length of 90mm. We photographed all University of California–Berkeley specimens using either a Nikon optiphot2-pol with a Nikon digital sight ds-fi2 attachment, or a Nikon Coolpix L24 digital camera.


Phylogenetic analysis.—Our matrix expands upon the matrix of Marjanović and Witzmann (2015), with the addition and/or adjustment of a few characters (Supplementary Data Sets 1, 2). Many of the characters in our matrix also use characters (Supplementary Data Set 1) first established in Wake and Özeti (1969), Titus and Larson (1995), Venczel (2008), and Schoch and Rasser (2013). Naylor (1978b) made a few adjustments to the morphology-based phylogeny of Wake and Özeti (1969), some of which are adopted in this analysis. We also added a few characters of our own to test their usefulness for analyzing North American taxa specifically (specimen availability did not allow us to make clear observations on taxa outside of North America for the purpose of coding these characters). We coded other characters relating to non-North American taxa according to the observations of Wake and Özeti (1969), Titus and Larson


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136  |  Page 137  |  Page 138  |  Page 139  |  Page 140  |  Page 141  |  Page 142  |  Page 143  |  Page 144  |  Page 145  |  Page 146  |  Page 147  |  Page 148  |  Page 149  |  Page 150  |  Page 151  |  Page 152  |  Page 153  |  Page 154  |  Page 155  |  Page 156  |  Page 157  |  Page 158  |  Page 159  |  Page 160  |  Page 161  |  Page 162  |  Page 163  |  Page 164  |  Page 165  |  Page 166  |  Page 167  |  Page 168  |  Page 169  |  Page 170  |  Page 171  |  Page 172  |  Page 173  |  Page 174  |  Page 175  |  Page 176  |  Page 177  |  Page 178  |  Page 179  |  Page 180  |  Page 181  |  Page 182  |  Page 183  |  Page 184  |  Page 185  |  Page 186  |  Page 187  |  Page 188  |  Page 189  |  Page 190  |  Page 191  |  Page 192  |  Page 193  |  Page 194  |  Page 195  |  Page 196  |  Page 197  |  Page 198  |  Page 199  |  Page 200  |  Page 201  |  Page 202  |  Page 203  |  Page 204  |  Page 205  |  Page 206  |  Page 207  |  Page 208  |  Page 209  |  Page 210  |  Page 211  |  Page 212  |  Page 213  |  Page 214  |  Page 215  |  Page 216  |  Page 217  |  Page 218  |  Page 219  |  Page 220  |  Page 221  |  Page 222  |  Page 223  |  Page 224  |  Page 225  |  Page 226  |  Page 227  |  Page 228  |  Page 229  |  Page 230  |  Page 231  |  Page 232