Huracan, Jiangzuo & Flynn & Wang & Hou & Deng, 2023

Jiangzuo, Qigao, Flynn, John J., Wang, Shiqi, Hou, Sukuan & Deng, Tao, 2023, New Fossil Giant Panda Relatives (Ailuropodinae, Ursidae): A Basal Lineage of Gigantic Mio-Pliocene Cursorial Carnivores, American Museum Novitates 2023 (3996), pp. 1-72 : 43-45

EVOLUTION OF HURACAN

So far, three species can be definitely assigned to the new taxon Huracan , two from North America (the genotype H. schneideri and H. coffeyi ) and another from eastern Asia ( China) ( H. qiui ). This clade appears to include a fourth species, from Europe ( Spain) (H. [“ Agriotherium ”] roblesi ), and possibly a fifth, from southern Asia (?“ H. ” punjabiensis ).

The two North American species may represent chronospecies, as they are temporally sequential and nonoverlapping, share diagnostic apomorphies distinguishing them from all

Miomaci panonnicum Miomaci panonnicum Kretzoiarctos beatrix Kretzoiarctos beatrix Indarctos arctoides Indarctos arctoides Indarctos vireti Indarctos vireti Agriotherium sivalense Indarctos zdanskyi Agriotherium palaeindicum Indarctos oregonensis Agriotherium insigne Indarctos atticus Agriotherium africanum Indarctos lagrelii Agriotherium inexpetans Agriotherium sivalense

Agriotherium hendeyi Agriotherium palaeindicum Huracan schneideri Agriotherium insigne Huracan coffeyi Agriotherium africanum Huracan qiui Agriotherium inexpetans ? " Huracan " punjab i ensis Agriotherium hendeyi Indarctos zdanskyi Huracan schneideri Indarctos oregonensis Huracan coffeyi Indarctos atticus Huracan qiui Indarctos lagrelii ?" Huracan " punjabiensis Indarctos anthracitis Indarctos anthracitis Ailurarctos lufengensis Ailurarctos lufengensis Ailuropoda melanolecua Ailuropoda melanolecua Ailurarctos yuanmouensis Ailurarctos yuanmouensis Ursus arctos Ursus arctos Ursus americanus Ursus americanus Ursus thibetanus Ursus thibetanus Ursus maritimus Ursus maritimus Ursavus tedfordi Ursavus tedfordi Ursavus brevirhinus Ursavus brevirhinus

Ballusia elmensis Ballusia elmensis Dinocyon thenardi Dinocyon thenardi Plithocyon teihardi Plithocyon teihardi Phoberocyon youngi Phoberocyon youngi Canis lupus Canis lupus other species, and the older species is differentiated from the younger only by lacking diagnostic apomorphies of the younger species and thus may represent a metaspecies. The Hh3- aged species H. coffeyi previously was viewed as synonymous with H. schneideri ( Miller and Carranza-Castaóeda, 1996; Hunt, 1998; Jiangzuo and Flynn, 2019), whose type is from the Upper Bone Valley, Hh4. Our observations on new specimens from the type locality of H. schneideri , and our review of all Hh4-age material of this group, suggest that H. schneideri shows stable differences from Hh3-age specimens, e.g., shorter M1 and M2 with smaller M2 talon, m1 with overall smaller size, and smaller posterior entoconid and weak or no subdivision of the m2 entoconid. Other differences in H. schneideri include smaller, more reduced premolars, and weaker anterior accessory cusps and the presence of medial ridge in p4, but these traits are known only from the type mandible of H. schneideri and the variability of these two characters within this species is unknown. Hh4-aged H. schneideri varies widely in size, e.g., the type specimen has a smaller dental size than that of any Hh3 Huracan , but its mandible size falls within the variation of that of Hh3-aged Huracan ( fig. 18 ). But whether this represents a smaller average dental (toothrow) size or stronger sexual dimorphism (mandible size) is still unclear. Among the potential names for Hh3-aged Huracan , H. coffeyi ( Dalquest, 1986) from Coffee Ranch should be used. The holotype is a mandible with well-preserved teeth, similar to other Hh3-aged Huracan specimens we observed, and therefore H. coffeyi is the valid name for Hh3-aged Huracan .

The Asian species H. qiui represents a more anatomically primitive form in having a narrower rostrum, double-rooted P2, and more elongated M1 and M2 (therefore is more Indarctos -like than H. coffeyi ). Morphologically and temporally, it is probably close to the ancestral lineage of the North American and European Huracan species.

Another species that can be assigned to Huracan is “ Agriotherium ” roblesi from Venta del Moro of Spain, MN 13 ( Morales and Aguirre, 1976). This species was initially known only from M1 and M2. Both teeth are very close in morphology to those of H. coffeyi , especially in their large size and distinct but short M2 talon. Recently, a P4 and several new mandibles have been discovered at the type locality ( Montoya et al., 2002; 2006; Morales et al., 2011), although a detailed description of that material is not yet published. Based on plate 2 of Montoya et al. (2006) and figure 2 of Morales et al. (2011), we can see that this species indeed has an Indarctos -like lower m1 (metaconid and double entoconid) and a premasseteric fossa, in accord with diagnostic features of Huracan . Based on the M1 and M2, this species shares diagnostic features of Huracan in having short M1 and M2, with small but distinct talon. The shape of these two teeth in H. roblesi is closer to those of Huracan coffeyi than to those of the Asian species H. qiui , so the specieswould be a member of the Huracan clade as H. roblesi . Since only the M1 and M2 were formally published, this species is not included in the phylogenetic analysis.

The southern Asian species?“ H. ” punjabiensis has an M2 with a relatively short talon, also in accord with diagnostic features of Huracan ( Jiangzuo and Flynn, 2019) . Its M1 also is anteroposteriorly shortened. However, the P4 of this species is different in having a small parastyle, and therefore is more Indarctos -like. A large P4 parastyle is a synapomorphy of Huracan and Agriotherium , so?“ H. ” punjabiensis appears to be more closely related to these two taxa than to Indarctos based on its upper molar morphology, but is probably slightly more primitive than the ancestral anatomical form of the P4 for the Huracan / Agriotherium clade. The phylogeny ( fig. 20 ) supports it as the nearest outgroup of Huracan and Agriotherium , so it probably should be assigned to a distinct genus. Due to the paucity of material of this species, however, erecting a new genus would be premature and could create unnecessary confusion and instability to the taxonomy for this group. We thus cannot definitively assign it to any genus, but given the overall similarity of the available material of this taxon to Huracan , we provisionally treat it as?“ H. ” punjabiensis herein. Previously, Baryshnikov (2002) proposed conspecificity of this species and the type species of Indarctos , i.e., I. atticus , therefore referring all European I. atticus to I. punjabiensis . This view was followed by some authors ( Abella et al., 2019). We do not regard these two species as conspecific, and instead regard the European material previously assigned to I. punjabiensis as I. atticus .

Figures

FIG. 18. Dental and mandible plots of Huracan and related taxa, with emphasis on dental length and its with/ length ratio, ratio of length between different teeth, and premolar/molar row length.

FIG. 20. Phylogenetic trees of Agriotheriini: A. strict consensus tree, parsimony with equal weighting, tree length 473, CI = 0.548, RI = 0.834; B. single most parsimonious tree, parsimony with implied weighting (k = 12), tree length 16.16, CI = 0.549, RI = 0.835. Number in the node represents bootstrap value (1000 times).