Table 1.
Locality, meter level, and stratotype information for Baena arenosa and Chisternon undatum specimens described in the present study.
Fig 1.
Map showing the geographic location of the Uinta Basin, Utah.
The gray region demarcates the Tertiary deposits of the Uinta Basin (Utah) and Piceance Creek (Colorado). Star indicates the study area of Uintan NALMA localities from which the baenid specimens described herein were recovered, between the Green and White Rivers.
Fig 2.
Cranial elements from Baena arenosa specimen UMNH VP 27535 from the Uinta Basin, Uinta Formation, Utah.
(A-A') Ventral view of basicranium. (B-B') Dorsal view of basciranium. (C) Right squamosal: Medial view (above), lateral view (below). (D) Left and right quadrates (on left and right, respectively): Anterior view (above), posterior view (below). (E-E') Neurocranium: Ventral view (left), dorsal view (right). (F) Maxillary fragments: Lateral view (above), medial view (below). (G) Lower jaw fragments: Articular (left), prearticular (middle), coronoid (right); Internal view (above), external view (below). Abbreviations: bo = basioccipital; bof = basioccipital foramen; bs = basisphenoid; btb = basis tuberculi basalis; cav cr = cavum cranii; cdb = crista dorsalis basioccipitalis; cnv = canali nervi vidiani; cond oc = condylus occipitalis; ds = dorsum sellae; ex = exoccipital; facc = foramina anterius canalis carotici interni; fja = foramen jugulare anterius; jjp = foramen jugulare posterius; fna = foramen nervi abducentis; fnh = foramen nervi hypoglossi; for so = foramen supraorbitale; fos temp = fossa temporalis; fpcci = foramen posterius canalis carotici interni; fr = frontal; fr-na = fronto-nasal suture; na = nasal; or = orbit; pa = parietal; pa-sao = parietal-supraoccipital suture; ppi = processus parietalis inferior; pt = pterygoid; rb = rostrum basisphenoidale; st = sella turcica; sul olf = sulcus olfactorius; tub bas = tuberculum basioccipitale; vp = vertical plate of parietal.
Fig 3.
Postcranial elements from Uintan Baena arenosa specimen UMNH VP 27535.
(A) Vertebral centrum: Posterior view (left), anterior view (right). (B) Vertebral centrum with transverse process: Posterior view (left), anterior view (right); (C-D) Cervical ribs: Caudal surface (left), cranial surface (right). (E) Scapular blade: Rostral surface. (F) Long bone fragments. (G) Anterior plastral section: Dorsal view. (G') Schematic depiction of epiplastron illustrating sigmoidal shaped humeral-extragular sulcus (in red). (H) Neural elements: Ventral view. Black arrows indicate positions of plastral sulci. Abbreviations: Eg = Extragular scale; Gs = Gular scale; Hu = Humeral scale.
Table 2.
Dimensions of postcranial bone elements in Baena specimen UMNH VP 27535.
Fig 4.
Baena arenosa carapace specimen from the Uinta Basin, UMNH VP 27604.
(A) Right lateral view of the carapace of UMNH VP 27604. (B) Superior view of the carapace of UMNH VP 27604. Note the original curvature of the dome of UMNH VP 27604, one of the most complete B. arenosa carapace specimens from the Uinta Basin. Abbreviations: Pl = pleural scale; Ve = vertebral scale.
Fig 5.
Carapace and plastron of Uintan Baena arenosa specimen UMNH VP 27191.
(A-A') Dorsal view of carapace. (B) Ventral view of carapace. (B') Increased magnification of vertebral elements affixed to internal surface of carapace. (C-C') Ventral view of plastron. (D) Dorsal view of plastron. Red arrows indicate puncture pits consistent with carnivore bite marks. Abbreviations: Ab = abdominal scale; An = anal scale; Ce = cervical scale; Eg = extragular scale; Fe = femoral scale; FeA = femoral-anal sulcus; Gs = gular scale; Hu = humeral scale; HEg = humeral-extragular sulcus; Ma = marginal scale; Pe = pectoral scale; Pl = pleural scale; Ve = vertebral scale.
Fig 6.
Two anterior carapace specimens of Uintan Baena arenosa.
(A) Dorsal view of UMNH VP 27653 carapace. (B) Ventral view of UMNH VP 27653 carapace. (C) Anterior carapace of UMNH VP 27539 (dorsal view). (D) Mid-carapace section of UMNH VP 27539 with pitting (dorsal view). Red arrow indicates puncture pit consistent with carnivore tooth mark.
Fig 7.
Two Uintan Baena arenosa carapace specimens.
(A) Dorsal view of UMNH VP 27541 carapace. (B) Ventral view of UCMP 179495 carapace.
Fig 8.
Posterior carapace and plastron sections from Uintan Baena arenosa specimen UMNH VP 27192.
(A) External view of plastron and carapace. (B) Internal view of plastron and carapace.
Fig 9.
Two Baena arenosa plastral specimens from the Uinta Basin, UMNH VP 27085 and UMNH VP 27542.
(A) Ventral view of the plastron of UMNH VP 27085. (B) Dorsal surface of midline carapace fragment from UMNH VP 27085. (C) Dorsal view of UMNH VP 27542 plastron.
Fig 10.
Carapace and plastron fragments of Uintan Baena arenosa specimen UMNH VP 27546.
(A) Dorsal view of carapace fragments. (B) Ventral view of carapace fragments. (C) Ventral view of plastron. (D) Dorsal view of plastron. Red arrow indicates puncture pit consistent with carnivore tooth mark. Note that this specimen was recovered from the Uinta Formation/Duchesne River Formation contact, making it the youngest baenid specimen described in the present study.
Fig 11.
Carapace and plastron fragments of Uintan subadult Baena arenosa specimens UMNH VP 27540 and UCMP 179520.
(A) Dorsal view of carapace of UMNH VP 27540. (B) Ventral view of carapace of UMNH VP 27540. (C) Ventral view of plastron of UMNH VP 27540. (D) Dorsal view of plastron of UMNH VP 27540. (E) Ventral view of UCMP 179520 plastral fragments. (F) Ventral view of UCMP 179520 carapace. Red arrows indicate puncture pits consistent with carnivore bite marks.
Fig 12.
Carapace and plastron fragments of Uintan subadult Baena arenosa specimen UMNH VP 27537.
(A) Dorsal view of carapace (left) and plastron (right). (B) Ventral view of carapace (left) and plastron (right). (C) Isolated bridge and peripheral elements with evidence of predation. Red arrows indicate puncture pits consistent with carnivore tooth marks.
Fig 13.
Schematic representations of morphological traits in newly described Uintan Baena arenosa (A-B) and Chisternon undatum (C-D) specimens. (A) Ventral plastron of Uintan B. arenosa. (B) Dorsal carapace of Uintan B. arenosa. (C) Ventral plastron of Uintan C. undatum. (D) Dorsal carapace of Uintan C. undatum. Differences from Gaffney (1979) [46] indicated in red. Uintan baenid specimens generally differ from previously described B. arenosa and C. undatum morphology in having: sigmoidal humeral-extragular sulci, multiple cervical scales, and small subtriangular gular scales. Abbreviations: Ab = Abdominal scale; An = Anal scale; Ce = Cervical scale; co = costal; Eg = Extragular scale; epi = epiplastron; ent = entoplastron; Fe = Femoral scale; FeA = Femoral-Anal sulcus; Gs = Gular scale; HEg = Humeral-Extragular sulcus; Hu = Humeral scale; hyo = hyoplastron; hyp = hypoplastron; mes = mesoplastron; ne = neural; nu = nuchal; Pe = Pectoral scale; per = peripheral; Pl = Pleural scale; pn = preneural; Pp = Prepleural scale; py = pygal; spy = suprapygal; Ve = Vertebral scale; xi = xiphiplastron. Following Gaffney (1979) [46], abbreviations for scales are capitalized, while those for bony elements are indicated with lowercase.
Fig 14.
Carapace and plastron of Uintan Chisternon undatum specimen UMNH VP 27554.
(A) Dorsal view of carapace. (B) Ventral view of carapace. (C) Ventral view of plastron. (D) Dorsal view of plastron. Abbreviations: Ab = abdominal scale; An = anal scale; Ce = cervical scale; Eg = extragular scale; Fe = femoral scale; FeA = femoral-anal sulcus; Gs = gular scale; Hu = humeral scale; HEg = humeral-extragular sulcus; Ma = marginal scale; Pe = pectoral scale; Pl = pleural scale; Ve = vertebral scale.
Fig 15.
Partial Uintan Chisternon undatum specimen, UCMP VP 27652.
Dorsal view of carapace.
Fig 16.
Carapace and plastron fragments of Uintan subadult Chisternon undatum specimen UMNH VP 27544.
(A) Dorsal view of carapace. (B) Ventral view of carapace. (C) Ventral view of plastron. (D) Dorsal view of plastron. Red arrows indicate puncture pits consistent with carnivore tooth marks.
Fig 17.
Results of phylogenetic analysis of Baenidae, incorporating newly described variation in Uintan Baena arenosa and Chisternon undatum.
Majority rule consensus cladogram of 72 most parsimonious trees. Percentages of trees supporting each node are indicated. B. arenosa and C. undatum were found to be sister taxa in 52% of the minimum length trees.