Morphobank

Project 530: R. W. Boessenecker, M. Churchill. 2013. A Reevaluation of the Morphology, Paleoecology, and Phylogenetic Relationships of the Enigmatic Walrus Pelagiarctos. PLOS ONE. 8 (1):e54311.

Specimen: † Pelagiarctos sp. Barnes, 1988 (SDNHM/uncatalogued)

More images »

Abstract

Background
A number of aberrant walruses (Odobenidae) have been described from the Neogene of the North Pacific, including specialized suction-feeding and generalist fish-eating taxa. At least one of these fossil walruses has been hypothesized to have been a specialized predator of other marine mammals, the middle Miocene walrus Pelagiarctos thomasi from the Sharktooth Hill Bonebed of California (16.1–14.5 Ma).
Methodology/Principal Findings
A new specimen of Pelagiarctos from the middle Miocene “Topanga” Formation of southern California (17.5–15 Ma) allows a reassessment of the morphology and feeding ecology of this extinct walrus. The mandibles of this new specimen are robust with large canines, bulbous premolars with prominent paraconid, metaconid, hypoconid cusps, crenulated lingual cingula with small talonid basins, M2 present, double-rooted P3–M1, single-rooted P1 and M2, and a P2 with a bilobate root. Because this specimen lacks a fused mandibular symphysis like Pelagiarctos thomasi, it is instead referred to Pelagiarctos sp. This specimen is more informative than the fragmentary holotype of Pelagiarctos thomasi, permitting Pelagiarctos to be included within a phylogenetic analysis for the first time. Analysis of a matrix composed of 90 cranial, dental, mandibular and postcranial characters indicates that Pelagiarctos is an early diverging walrus and sister to the late Miocene walrus Imagotaria downsi. We reevaluate the evidence for a macropredatory lifestyle for Pelagiarctos, and we find no evidence of specialization towards a macrophagous diet, suggesting that Pelagiarctos was a generalist feeder with the ability to feed on large prey.
Conclusions/Significance
This new specimen of Pelagiarctos adds to the knowledge of this problematic taxon. The phylogenetic analysis conclusively demonstrates that Pelagiarctos is an early diverging walrus. Pelagiarctos does not show morphological specializations associated with macrophagy, and was likely a generalist predator, feeding on fish, invertebrates, and the occasional warm-blooded prey item.

Read the article »

Project DOI: 10.7934/P530, http://dx.doi.org/10.7934/P530

This project contains	Matrices
624 Media 2 Matrices 1 Document 27 Taxa 36 Specimens 90 Characters Total size of project's media files: 1.18G Download Project SDD File	Total scored cells: 2432 Total media associated with cells: 581 Total labels associated with cell media: 556
	Characters
	Total characters: 129 Total characters with associated media: 0 Total characters with media with labels: 0 Total character states: 249 Total character states with associated media: 79 Total character states with media with labels:78 Total unordered/ordered characters:129/0

Currently Viewing:
MorphoBank Project 530

Creation Date:
12 June 2011
Publication Date:
16 January 2013
Project views: 229167
Media downloads: 55
Matrix downloads: 72

This research
supported by

Authors' Institutions

University of Otago

University of Wyoming

Members

Morgan Churchill
Project Administrator

527

2026
(2026, 0, 0)

223

200

Robert Boessenecker
Full membership

156

406
(406, 0, 0)

358

356

Taxonomic Overview for Matrix 'M1174' (20 Taxa)

taxon	unscored cells	scored cells	no cell support	NPA cells	"-" cells	cell images	labels on cell images	member access
[1] † Enaliarctos emlongi Last Modified in 12/05/13	0	39	7	0	0	31	24	2
[2] † Pteronarctos goedertae Last Modified in 12/05/13	0	39	11	0	0	27	27	2
[3] † Desmatophoca oregonensis Last Modified in 12/05/13	0	39	5	0	0	33	31	2
[4] † Allodesmus gracilis Last Modified in 12/05/13	0	39	12	0	0	27	26	2
[5] Monachus monachus Last Modified in 12/05/13	0	39	4	0	0	35	33	2
[6] Erignathus barbatus Last Modified in 12/05/13	0	41	6	0	0	33	31	2
[7] Callorhinus ursinus Last Modified in 12/05/13	1	38	6	0	0	32	30	2
[8] † Proneotherium repenningi Last Modified in 12/05/13	0	39	6	0	0	37	36	2
[9] † Kamtschatarctos sinelnikovae Last Modified in 12/05/13	9	30	5	0	0	25	24	2
[10] † Neotherium mirum Last Modified in 12/05/13	0	39	31	0	0	6	6	2
[11] † Imagotaria downsi Last Modified in 12/05/13	0	44	4	0	0	58	56	2
[12] † Pelagiarctos sp. Last Modified in 12/05/13	5	34	2	0	0	33	33	2
[13] † Pontolis magnus Last Modified in 12/05/13	1	38	37	0	0	0	0	2
[14] † Gomphotaria pugnax Last Modified in 12/05/13	5	34	4	0	0	28	28	2
[15] † Dusignathus santacruzensis Last Modified in 12/05/13	0	39	4	0	0	34	37	2
[16] † Dusignathus seftoni Last Modified in 12/05/13	7	33	5	0	0	25	25	2
[17] † Protodobenus japonicus Last Modified in 12/05/13	1	38	3	0	0	33	31	2
[18] † Ontocetus emmonsi Last Modified in 12/05/13	1	38	3	0	0	37	37	2
[19] † Valenictus chulavistensis Last Modified in 12/05/13	19	20	6	0	0	14	13	2
[20] Odobenus rosmarus Last Modified in 12/05/13	2	37	4	0	0	33	28	2

Taxonomic Overview for Matrix 'M1891' (23 Taxa)

taxon	unscored cells	scored cells	no cell support	NPA cells	"-" cells	cell images	labels on cell images	member access
[1] † Enaliarctos emlongi Last Modified in 12/05/13	8	82	80	0	0	0	0	2
[2] † Pteronarctos goedertae Last Modified in 12/05/13	8	82	81	0	0	0	0	2
[3] Callorhinus ursinus Last Modified in 12/05/13	1	89	89	0	0	0	0	2
[4] † Desmatophoca oregonensis Last Modified in 12/05/13	6	86	83	0	0	0	0	2
[5] † Allodesmus gracilis Last Modified in 12/05/13	0	92	90	0	0	0	0	2
[6] Erignathus barbatus Last Modified in 12/05/13	0	92	90	0	0	0	0	2
[7] Monachus monachus Last Modified in 12/05/13	0	90	90	0	0	0	0	2
[8] † Prototaria primigenia Last Modified in 12/05/13	47	43	43	0	0	0	0	2
[9] † Proneotherium repenningi Last Modified in 12/05/13	8	82	81	0	0	0	0	2
[10] † Neotherium mirum Last Modified in 12/05/13	1	89	87	0	0	0	0	2
[11] † Kamtschatarctos sinelnikovae Last Modified in 12/05/13	49	41	40	0	0	0	0	2
[12] † Pseudotaria muramotoi Last Modified in 12/05/13	54	36	36	0	0	0	0	2
[13] † Imagotaria downsi Last Modified in 12/05/13	1	96	88	0	0	0	0	2
[14] † Pelagiarctos sp. Last Modified in 12/05/13	56	34	33	0	0	0	0	2
[15] † Pontolis magnus Last Modified in 12/05/13	3	87	86	0	0	0	0	2
[16] † Dusignathus santacruzensis Last Modified in 12/05/13	35	55	53	0	0	0	0	2
[17] † Dusignathus seftoni Last Modified in 12/05/13	16	76	70	0	0	0	0	2
[18] † Gomphotaria pugnax Last Modified in 12/05/13	13	77	74	0	0	0	0	2
[19] Aivukus cedrosensis Last Modified in 12/05/13	32	58	58	0	0	0	0	2
[20] † Protodobenus japonicus Last Modified in 12/05/13	26	64	61	0	0	0	0	2
[21] † Ontocetus emmonsi Last Modified in 12/05/13	2	88	87	0	0	0	0	2
[22] † Valenictus chulavistensis Last Modified in 12/05/13	22	68	68	0	0	0	0	2
[23] Odobenus rosmarus Last Modified in 12/05/13	2	88	88	0	0	0	0	2

Project views

type	number of views	Individual items viewed (where applicable)
Total project views	229167
Project overview	5667
Matrix views	3683	Matrix landing page (2916 views); Kohno 2006 modified matrix (371 views); walrus mandible and lower dentition (396 views);
Media views	154809	Media search (9897 views); M86601 (785 views); M86654 (749 views); M86662 (767 views); M86648 (831 views); M101358 (536 views); M148227 (9 views); M86643 (796 views); M86669 (815 views); M86655 (744 views); M86221 (758 views); M148428 (10 views); M86649 (759 views); M86656 (758 views); M93589 (925 views); M86598 (815 views); M148291 (19 views); M86657 (794 views); M86674 (751 views); M86647 (732 views); M86652 (791 views); M86653 (794 views); M86644 (800 views); M107639 (41 views); M86720 (733 views); M86719 (741 views); M101444 (465 views); M101426 (517 views); M101435 (438 views); M107650 (48 views); M93595 (410 views); M93594 (424 views); M93593 (408 views); M93592 (388 views); M93591 (425 views); M93590 (705 views); M93580 (626 views); M86730 (680 views); M101348 (485 views); M148322 (20 views); M101345 (539 views); M101391 (554 views); M101452 (482 views); M101416 (568 views); M101447 (524 views); M101428 (466 views); M101338 (527 views); M101342 (533 views); M148289 (19 views); M148299 (22 views); M148298 (20 views); M148309 (22 views); M148313 (20 views); M148317 (16 views); M148321 (26 views); M101441 (447 views); M101449 (425 views); M148212 (14 views); M101377 (536 views); M101343 (505 views); M101423 (508 views); M101421 (518 views); M101379 (528 views); M86732 (721 views); M101334 (503 views); M106621 (37 views); M101396 (491 views); M101335 (515 views); M101353 (482 views); M101403 (499 views); M101431 (499 views); M101356 (533 views); M106613 (87 views); M101434 (373 views); M101436 (426 views); M101440 (399 views); M101445 (392 views); M101446 (477 views); M101448 (479 views); M101450 (428 views); M101451 (394 views); M101453 (423 views); M101433 (545 views); M101420 (518 views); M107658 (39 views); M101336 (524 views); M101337 (520 views); M101339 (531 views); M101340 (555 views); M101341 (513 views); M101344 (509 views); M101346 (494 views); M101347 (570 views); M101349 (552 views); M101350 (477 views); M101351 (497 views); M101352 (515 views); M101354 (516 views); M101355 (505 views); M101357 (549 views); M101359 (550 views); M101360 (541 views); M101361 (530 views); M101362 (592 views); M101363 (511 views); M101364 (518 views); M101365 (564 views); M101366 (522 views); M101367 (516 views); M101368 (517 views); M101369 (500 views); M101370 (612 views); M101371 (531 views); M101372 (557 views); M101373 (552 views); M101374 (570 views); M101375 (528 views); M101376 (537 views); M101378 (508 views); M101380 (470 views); M101381 (462 views); M101382 (600 views); M101383 (512 views); M101384 (543 views); M101385 (528 views); M101386 (541 views); M101387 (529 views); M101388 (518 views); M101389 (522 views); M101390 (515 views); M101392 (524 views); M101393 (505 views); M101394 (534 views); M101395 (567 views); M101397 (526 views); M101398 (546 views); M101399 (441 views); M101400 (459 views); M101401 (484 views); M101402 (515 views); M101404 (621 views); M101405 (528 views); M101406 (545 views); M101407 (515 views); M101408 (539 views); M101409 (537 views); M101410 (503 views); M101411 (546 views); M101412 (468 views); M101413 (520 views); M101414 (535 views); M101415 (512 views); M101417 (536 views); M101418 (533 views); M101419 (487 views); M101422 (524 views); M101424 (525 views); M101425 (513 views); M101427 (500 views); M101429 (501 views); M101430 (555 views); M101432 (520 views); M101437 (411 views); M101438 (457 views); M101439 (394 views); M101442 (430 views); M101443 (373 views); M107688 (44 views); M107642 (37 views); M86708 (633 views); M86684 (723 views); M86709 (683 views); M148204 (16 views); M107680 (61 views); M107661 (52 views); M107643 (47 views); M107668 (52 views); M107690 (61 views); M86699 (720 views); M86711 (653 views); M106633 (34 views); M107637 (42 views); M107672 (35 views); M106630 (50 views); M107683 (44 views); M106625 (33 views); M148293 (21 views); M107671 (46 views); M86645 (805 views); M86678 (770 views); M107685 (44 views); M106620 (46 views); M106614 (78 views); M86722 (665 views); M86681 (702 views); M106618 (41 views); M148189 (14 views); M86666 (787 views); M107689 (78 views); M106626 (48 views); M93584 (735 views); M86696 (715 views); M107636 (40 views); M107646 (49 views); M106611 (96 views); M107684 (40 views); M148318 (16 views); M148325 (19 views); M148338 (25 views); M86659 (764 views); M107657 (35 views); M86663 (799 views); M107673 (41 views); M101459 (43 views); M107647 (36 views); M106627 (37 views); M101468 (81 views); M148304 (18 views); M148358 (11 views); M86698 (686 views); M107651 (40 views); M107681 (44 views); M86688 (716 views); M86650 (804 views); M86665 (727 views); M86670 (726 views); M86668 (768 views); M86677 (789 views); M106634 (36 views); M86661 (811 views); M86673 (753 views); M107692 (44 views); M101464 (79 views); M101465 (42 views); M86671 (767 views); M106615 (118 views); M107676 (112 views); M86721 (717 views); M101469 (94 views); M106631 (39 views); M106617 (39 views); M86703 (656 views); M86728 (656 views); M107667 (52 views); M86642 (746 views); M86651 (759 views); M86700 (703 views); M86701 (676 views); M86702 (663 views); M86704 (686 views); M86705 (655 views); M86706 (637 views); M86707 (646 views); M86724 (747 views); M86725 (691 views); M86726 (703 views); M93581 (683 views); M93582 (648 views); M93583 (700 views); M93585 (693 views); M93586 (672 views); M93587 (708 views); M93588 (705 views); M86731 (710 views); M86600 (805 views); M86646 (820 views); M86660 (789 views); M86664 (776 views); M86667 (711 views); M86679 (742 views); M86680 (696 views); M86682 (719 views); M86683 (738 views); M86685 (715 views); M86686 (690 views); M86687 (661 views); M86689 (666 views); M86694 (760 views); M86695 (736 views); M86727 (729 views); M86729 (723 views); M86733 (693 views); M107677 (54 views); M107687 (44 views); M148283 (22 views); M107669 (53 views); M106619 (43 views); M107679 (43 views); M86672 (767 views); M86675 (770 views); M86676 (752 views); M86710 (688 views); M86713 (693 views); M86714 (656 views); M86718 (698 views); M86723 (650 views); M107648 (42 views); M148264 (18 views); M107634 (50 views); M107670 (92 views); M107662 (38 views); M148203 (15 views); M148240 (13 views); M148229 (13 views); M107702 (7 views); M148219 (5 views); M101460 (113 views); M107691 (50 views); M106610 (41 views); M106612 (80 views); M106616 (73 views); M106622 (38 views); M106623 (49 views); M106624 (36 views); M106628 (32 views); M106629 (48 views); M106632 (40 views); M106635 (40 views); M106636 (38 views); M106637 (53 views); M107653 (51 views); M101457 (72 views); M148417 (9 views); M148369 (8 views); M148233 (13 views); M148403 (9 views); M86717 (704 views); M107652 (41 views); M107644 (36 views); M107664 (38 views); M86716 (726 views); M101463 (78 views); M107665 (36 views); M101458 (71 views); M107633 (27 views); M107635 (47 views); M107638 (36 views); M107645 (39 views); M107649 (35 views); M107654 (61 views); M107655 (38 views); M107656 (42 views); M107659 (35 views); M107660 (41 views); M107663 (39 views); M107666 (46 views); M107674 (42 views); M107675 (33 views); M148327 (16 views); M107640 (38 views); M107641 (38 views); M107678 (30 views); M107682 (36 views); M107686 (53 views); M101470 (47 views); M101461 (73 views); M148197 (5 views); M101454 (46 views); M101455 (39 views); M101456 (70 views); M101462 (95 views); M101466 (84 views); M101467 (33 views); M148279 (16 views); M148266 (16 views); M148273 (15 views); M148281 (14 views); M148336 (13 views); M148251 (14 views); M148320 (16 views); M148285 (14 views); M148476 (21 views); M148370 (11 views); M86715 (715 views); M148411 (9 views); M107703 (12 views); M148355 (6 views); M148246 (22 views); M148250 (14 views); M148295 (15 views); M107698 (13 views); M148422 (36 views); M148282 (18 views); M148372 (13 views); M148371 (9 views); M148232 (14 views); M148466 (12 views); M148462 (8 views); M148396 (9 views); M148296 (17 views); M148190 (14 views); M148201 (14 views); M148288 (19 views); M148359 (7 views); M148418 (15 views); M148414 (13 views); M148300 (16 views); M148455 (12 views); M148277 (15 views); M148471 (7 views); M148188 (4 views); M148335 (16 views); M148334 (21 views); M148328 (15 views); M148310 (16 views); M148305 (15 views); M148218 (4 views); M148392 (7 views); M148444 (12 views); M148395 (9 views); M148375 (19 views); M148380 (10 views); M148376 (10 views); M148445 (8 views); M148389 (8 views); M148217 (3 views); M148337 (15 views); M148453 (8 views); M148187 (4 views); M148432 (16 views); M148440 (7 views); M148193 (15 views); M148276 (17 views); M148208 (12 views); M148443 (13 views); M148252 (17 views); M148228 (9 views); M107695 (9 views); M148362 (9 views); M148231 (11 views); M107697 (6 views); M148191 (12 views); M148449 (8 views); M148357 (7 views); M148260 (16 views); M148353 (8 views); M148424 (7 views); M148280 (14 views); M148456 (10 views); M148377 (14 views); M148195 (13 views); M148351 (6 views); M148226 (11 views); M148378 (13 views); M148454 (8 views); M148211 (3 views); M148404 (8 views); M148384 (21 views); M148235 (3 views); M148312 (14 views); M148457 (8 views); M148326 (16 views); M148248 (15 views); M148421 (8 views); M148434 (7 views); M148397 (13 views); M148215 (11 views); M148361 (6 views); M148294 (15 views); M148323 (17 views); M148430 (8 views); M148415 (16 views); M148290 (14 views); M148436 (8 views); M148216 (13 views); M148465 (9 views); M148393 (23 views); M148477 (13 views); M148441 (16 views); M148249 (16 views); M148413 (9 views); M148194 (11 views); M148381 (16 views); M148347 (13 views); M148416 (16 views); M148368 (7 views); M148461 (7 views); M148350 (12 views); M107693 (17 views); M148245 (12 views); M148200 (6 views); M148448 (8 views); M148223 (12 views); M148374 (6 views); M107699 (13 views); M148255 (15 views); M148267 (14 views); M148382 (7 views); M148330 (16 views); M148206 (13 views); M148447 (11 views); M148341 (15 views); M148354 (8 views); M148460 (10 views); M148213 (4 views); M148442 (8 views); M148367 (9 views); M148315 (17 views); M148429 (8 views); M148261 (16 views); M148275 (15 views); M148329 (18 views); M148307 (17 views); M148437 (8 views); M148463 (7 views); M148242 (4 views); M148287 (16 views); M148352 (7 views); M148324 (16 views); M148364 (13 views); M148258 (13 views); M148234 (14 views); M148423 (8 views); M148450 (9 views); M148303 (15 views); M148365 (7 views); M148247 (16 views); M148446 (18 views); M148214 (12 views); M148237 (4 views); M148205 (15 views); M148272 (20 views); M148311 (15 views); M148475 (16 views); M148363 (13 views); M107694 (5 views); M148230 (7 views); M148210 (12 views); M148302 (16 views); M148427 (7 views); M148472 (13 views); M148346 (11 views); M148394 (5 views); M148349 (11 views); M148221 (5 views); M107700 (7 views); M148222 (16 views); M148405 (16 views); M148316 (19 views); M148306 (16 views); M148225 (5 views); M148297 (17 views); M148257 (15 views); M148253 (13 views); M148278 (15 views); M148269 (15 views); M148199 (12 views); M148391 (9 views); M148348 (7 views); M148343 (21 views); M148340 (15 views); M148209 (15 views); M148387 (7 views); M148198 (4 views); M148409 (4 views); M148241 (5 views); M148333 (17 views); M148243 (5 views); M148301 (16 views); M148344 (15 views); M148431 (6 views); M148262 (18 views); M148331 (16 views); M148274 (15 views); M148224 (15 views); M148356 (8 views); M148292 (16 views); M148286 (15 views); M148464 (9 views); M148236 (6 views); M148220 (5 views); M148388 (5 views); M148401 (5 views); M107701 (7 views); M148196 (4 views); M148468 (13 views); M148254 (17 views); M148319 (15 views); M148410 (7 views); M148470 (9 views); M148314 (16 views); M148459 (15 views); M148345 (16 views); M148271 (16 views); M148192 (13 views); M148259 (15 views); M148268 (18 views); M148383 (6 views); M148469 (8 views); M148385 (6 views); M148402 (11 views); M148458 (14 views); M148386 (5 views); M148239 (12 views); M148412 (7 views); M148435 (7 views); M148474 (7 views); M148373 (8 views); M148270 (17 views); M148263 (15 views); M148439 (9 views); M148398 (6 views); M148400 (11 views); M148238 (13 views); M148244 (10 views); M148360 (11 views); M148473 (13 views); M148366 (8 views); M148332 (16 views); M148265 (19 views); M148207 (7 views); M148408 (6 views); M148399 (6 views); M148426 (8 views); M148420 (6 views); M148433 (12 views); M148390 (12 views); M148467 (7 views); M107696 (15 views); M148202 (14 views); M148256 (17 views); M148339 (14 views); M148284 (14 views); M148342 (14 views); M148308 (18 views);
Specimen list	38157
Documents list	2421
Taxon list	18408
Bibliography	6022

Project downloads

type	number of downloads	Individual items downloaded (where applicable)
Total downloads from project	540
Matrix downloads	72	Kohno 2006 modified matrix (41 downloads); walrus mandible and lower dentition (31 downloads);
Project downloads	404
Document downloads	9	(9 downloads);
Media downloads	55	M86722 (2 downloads); M93595 (1 download); M93594 (1 download); M93593 (1 download); M93592 (1 download); M93591 (2 downloads); M93590 (1 download); M93589 (2 downloads); M93580 (4 downloads); M86649 (1 download); M86671 (1 download); M86669 (1 download); M86674 (1 download); M86221 (1 download); M101349 (1 download); M101352 (1 download); M101358 (1 download); M101356 (1 download); M101374 (1 download); M101377 (1 download); M101385 (1 download); M101382 (1 download); M101390 (2 downloads); M101393 (1 download); M101411 (1 download); M106613 (1 download); M106618 (1 download); M106628 (1 download); M148289 (1 download); M148294 (1 download); M148309 (1 download); M148308 (1 download); M148321 (1 download); M148343 (1 download); M86642 (1 download); M86600 (1 download); M86643 (1 download); M86645 (1 download); M86598 (1 download); M86648 (1 download); M86651 (1 download); M86652 (1 download); M86653 (1 download); M86654 (1 download); M86655 (2 downloads); M86656 (1 download); M86657 (1 download);