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Callichimaeridae fam. nov. LSID. urn:lsid:zoobank.org:act: A5D6688D-756B-4FB7-8098- 5EB066C38383 Included genus. Callichimaera gen. nov. Diagnosis. As for type genus and species., Published as part of Luque, J., Feldmann, R. M., Vernygora, O., Schweitzer, C. E., Cameron, C. B., Kerr, K. A., Vega, F. J., Duque, A., Strange, M., Palmer, A. R. & Jaramillo, C., 2019, Exceptional preservation of mid-Cretaceous marine arthropods and the evolution of novel forms via heterochrony, pp. 1-15 in Science Advances 5 (4) on page 3, DOI: 10.1126/sciadv.aav3875, http://zenodo.org/record/5902784

Callichimaera perplexa gen. et sp. nov. LSID. urn:lsid:zoobank.org:act: CD4585D1-B198-45E6-8485- 45F94167BDEE LSID. urn:lsid:zoobank.org:act: 650E5046-C4FC-4485-A3B5- 254DE785F80B Etymology. The section, superfamily, family, and generic names are derived from the Greek prefix calli- “kalos” (beautiful), alluding to its exceptional preservation, and Chimera, the fabulous mythological beastcommonlyrepresented ascomposedof parts of different animals such as the lion, goat, and snake, alluding to its startling combination of traits present in separate higher decapod taxa, e.g., eubrachyurans, podotreme brachyurans, anomurans, and some macrurans. Thespecific epithet derives from the Latin “perplexus,” referring to its puzzling anatomy and phylogenetic affinities. The gender is feminine. Diagnosis. Smallcrabs (carapace width, 21)]. Description. Seethe Supplementary Materialsforadetaileddescription of C. perplexa gen. et sp. nov. Holotype. IGM p881215, specimen preserved in ventral view (Fig. 1, Ato C), deposited in the paleontological collections of the Colombian Geological Survey, Diagonal 53 #34-53, Bogotá DC, Colombia. Carapace length is 8.5 mm, and carapace width is 5.2 mm. Additional material. Colombian paratypes IGM p881184 to IGM p881214 and IGM p881216 to IGMp881221 are deposited in the paleontological collections of the Colombian Geological Survey; paratypes MUN-STRI 27044-01 to MUN-STRI 27044-010 and MUN-STRI 27045-01 to MUN-STRI 27045-020 aredepositedinthe Mapuka Museum of Universidad del Norte, Barranquilla, Colombia. Additional nontype materials from the United States, specimens USNM 605049 to USNM 605056, aredepositedinthe Paleobiology Collections of the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA. Measurements. The range of measurements is as follows: Holotypehas acarapacelengthof 8.5 mmandacarapacewidthof 5.2 mm, the smallestparatype IGM p881220 has a carapace length of 6.6 mm and a carapace width of 3.8 mm, and the largest paratype MUN-STRI 27045-015 has a carapace length of 15.1 mm and a carapace width of 9.6 mm. Type locality, age, and horizon. Churuvita Group, upper Cenomanian to lower Turonian (~95 to 90 Ma ago), Pesca, Boyacá, Colombia (data files S1 and S2), from carapace- and appendagerich surfaces. Other specimens are from the Frontier Formation, lower-middle Turonian (~90 Ma ago), WY, USA. Seethe Supplementary Materials for a detailed description of the geological, geographical, and paleontological context. Systematic remarks Althoughmolecularandmorphological phylogeneticsbringpowerful toolstothestudyof relatednessatthe genotypicandphenotypic levels, the fossil record provides a unique view into the origins of such relatedness by revealing a past morphological diversity otherwise inaccessible. Furthermore, fossils are pivotal for understanding the evolutionof keytraits and provide geographic and chronologic data critical to the calibration of nodes of interest. Weconsider Callichimaeroidasectionnov.atruecrabor Brachyura insteadof Anomurabasedon thefollowing: (i) itsshort firstandsecond antennaebetween the eyes, (ii) a symmetric, sexually dimorphic pleon, (iii) the absence of articulating rings between pleonites, (iv) a reduced telson, (v) complete absence of uropods or uropodal plates, (vi) the presenceof modifiedmalepleopods 1 and 2 ashighly sclerotizedgonopods but lacking pleopods 3 to 5, while the female bears pleopods 2 to 5, (vii) third maxilliped with well-defined ischium and merus, (viii) the presence of only one pair of chelae or claws (pereopod 1), thus pereopods 2 to 5 are achelate, and (ix) P5 is well developed, visible in dorsal view, and neither subchelate nor modified for carrying or grasping (Figs. 1 to 3). However, a precise phylogenetic placement of Callichimaera within Brachyuraisproblematicbecauseof its “chimeric” nature, theunknownmoltinglinea, andpossessionof multipledistinctive characters typicalof several fossil and extant Brachyura and Anomura clades but not collectively seen in any one taxon. These characters include a lobster/raninid-like elongate carapace, pediform maxillipeds with a crista dentata, spanner-like chelipeds, large paddle-like legs P2 and P3, thedissimilarshape andsizeof itssternites, asymmetricalpleon lacking uropods or uropodal plates, a dorsally keeled carapace, and largeeyes lacking true orbits and orbital fissures (Figs. 1 to 3). Phylogenetic remarks Both molecular and morphological phylogenetic studies have recovered Brachyura, or true crabs, as a monophyletic and sister group to Anomura (false crabs and allies) (2, 10, 11, 22). Yet, phylogenetic relationships within Brachyura remain unsettled largely because of the lack of early, intermediate body forms. Results of our Maximum Parsimony (MP) and Maximum Likelihood (ML) analyses largely agree on the arrangement of ingroup taxa, including placement of Callichimaera as an independent lineage branching off before the extinct highertaxa †Torynommoida and †Etyoida (Fig. 5 and figs. S5, S6A, and S7). Although Callichimaera isalsorecoveredin thesame positionunder Implied Weight MP (IWMP) with moderate K values (K = 6) (fig. S6C), underlow K values (K = 3), Callichimaera is pulled into a clade with Palaeocorystidae and Raninidae + Lyreididaeasaresultof along-branchattractionduetothehomoplastic characters shared among decarcinized crabs and, therefore, artificially inflating the fit value of the tree (fig. S6B). Similarly, under IWMP high K values (K = 12), Callichimaera is pulled into a clade with Orithopsidae and Necrocarcinidae + Cenomanocarcinidae as a result of a long-branch attraction due to the convergentcarapaces ornamentedwithseveral dorsallongitudinalkeelsorcarina (fig. S6D). The Bayesian Inference (BI) consensus tree presents the least resolvedtopologywithseveralmajor brachyuranlineagescollapsedinto a polytomy, yet showsa clearparaphyletic podotremegrade (fig. S8). Discrepancies between topologiesrecovered by probabilistic methods (ML and BI) under the same model of evolution (Mk) are not unusualconsidering differences inthecriteria for selectingthe best ML and BI topologies. Since BI uses marginal likelihoods to select the optimal topology (as opposed to the joined likelihood in the ML estimation), it is more sensitive to inconsistencies in a dataset. Although BI has been shown to produce accurate topologies whendealing with morphological data (23, 24), themethod remains sensitive to the consistencyof the phylogenetic signal present in the dataset, selection of priors, and heterogeneity of evolutionary rates across different lineages on a tree. The lack of resolution in our BI consensus topology is best explained by high topological disparity in the posterior sample of trees, caused by multiple cases of convergent traits and disparity inevolutionary rates (pedomorphosis, high phenotypic plasticity, etc.) across lineages. In light of the ongoing debate over relative performance of parsimony and model-based approaches when analyzing morphological data (23 – 29), we present results of phylogenetic analyses under multiple optimality criteria, which agree in the placement of Callichimaeridae as a new, independent lineage.

Callichimaeroida section nov. Included superfamily. Callichimaeroidea fam. nov. Diagnosis. As for superfamily., Published as part of Luque, J., Feldmann, R. M., Vernygora, O., Schweitzer, C. E., Cameron, C. B., Kerr, K. A., Vega, F. J., Duque, A., Strange, M., Palmer, A. R. & Jaramillo, C., 2019, Exceptional preservation of mid-Cretaceous marine arthropods and the evolution of novel forms via heterochrony, pp. 1-15 in Science Advances 5 (4) on page 2, DOI: 10.1126/sciadv.aav3875, http://zenodo.org/record/5902784

Callichimaeroidea superfam. nov. Included family. Callichimaeridae fam. nov. Tentatively Retrorsichelidae Feldmann et al. (20). Diagnosis. Crabs with carapaces longer than wide, small and fusiform (Callichimaeridae), or large and ovate (Retrorsichelidae). Sternites 1 to 4 are fused and visible ventrally, forming an elongated sternal crown; sternite 4 is not mesially depressed; sternites 5 to 7 are unfused and axially sulcate by linea media; sternite 5 is very wide, almost as wide as the carapace; suture 5/6 is complete, but lacks a true sterno-pleonal cavity. Thepleon is symmetrical, sexually dimorphic, narrower in males than females, and in both sexes narrower than sternite 6 (Callichimaeridae). Pleonal somites are not fused, lacking articulating rings and bearing dorsal median tubercle or crest; pleonites 1 to 3 are exposed subdorsally; uropods or uropodal plates areabsent. True orbits, orbital fissures, or any protective structures are absent. Eyes are large in Callichimaeridae but are likely small and reduced in Retrorsichelidae. Chelipeds (claws) are isochelous, and the manus is stout, with pollex or fixed finger slightly (Retrorsichelidae) or strongly (Callichimaeridae) deflected downward; chelipedsarefoldedventrallyandposteriorlybeneath carapace. Pereopods (legs) P2 and P3 are much larger than P4 and P5; P4 and P5 are situatedsubdorsallyand directed posteriorly, lacking spines, neither subchelate nor modified for carrying or grasping. In Callichimaeridae, P2 and P3 are large and wide and positioned laterally, withdistal podomeres flattened and paddle-like; P4 and P5 are shortand narrow, withthedorsallongitudinalkeelneitherflattenednor paddle-like; P5 isthe smallest, well developed butreduced, and carried subdorsally. In Retrorsichelidae, P2 and P3 areapparentlylarge andpositioned ventrally; atleastone pereopod bearsflattened distal articles.

The great drama of China has been the repeated attempts to bring under single control and preserve the unity of its vast territories, so varied ethnically, socially, and geographically. Han Chinese confidence in the integrity of their own identity has been lastingly unsettled by long periods of fragmentation into regional states, and even in times of political unity the heart-searching has continued: what went wrong? What lessons could be learned for the future? The Southern and Northern Dynasties’ era (317-589 AD) was the longest period of political fragmentation in the imperial era. Its political and social confusion gave rise to differences in later accounts of it. In the eleventh century, scholar-officials intensively debated the issue of imperial rule during this period. At stake was the integrity of the Han Chinese state. On one side were historians who accorded legitimacy to the barbarian dynasties of the north; on the other were those who favoured the southern Han Chinese-ruled dynasties. By the time Song’s power base transferred south in 1127, a strong sense of a Han Chinese identity had developed and pro-Southern opinion predominated. This study approaches the Southern and Northern Dynasties’s era indirectly. It examines it through the most prominent work of eleventh-century historiography, the keystone written history of early imperial China, Sima Guang’s 司馬光 Zi zhi tong jian 資治通鑑 – the main focus of this study. That text has played a central role in shaping later understanding of imperial China’s political traditions and, as a corollary, has contributed to the formation of a Han Chinese self-identity. Yet Sima Guang’s representation of China’s past, though well-researched and written, was inevitably coloured by personal political and social experiences, and by his current commitments – by spin, in fact. This study will argue that at the heart of Sima Guang’s representation of the Southern and Northern Dynasties was a concern for the political survival of the eleventh-century state under which he served. He needed to understand and explicate the political and moral lessons of the earlier period in order to present an imperial vision that would avoid its frailties. This study therefore investigates and demonstrates the previously unexplored extent to which contemporary political concerns informed Sima Guang’s account. By developing a reading of Zi zhi tong jian as an ideological and textual construct, and more than just a simple account of the past, this study affords insights into the composition of historical writing in imperial China, as well as the complexities of the political environment that spawned it. It shows that works of historiography like Zi zhi tong jian served a more nuanced function than later scholarship suggests, and it brings into focus important questions of historical and literary authority.

AIAA, May 1998, Boston, Massachusetts

American Helicopter Society's 54th Annual Forum, Washington, DC

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