Table of Content

20 April 2024, Volume 62 Issue 2

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A taxonomical revision of ‘Dongfangaspis qujingensis’ from the Lower Devonian of Qujing, Yunnan Province

SHAN Xian-Ren, ZHU Min, LI Qiang, GAI Zhi-Kun

2024, 62(2):  85-98.  DOI: 10.19615/j.cnki.2096-9899.240321

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The affinity of ‘Dongfangaspis qujingensis’, initially assigned to Dongfangaspis but later to Laxaspis, has long been controversial. However, the taxonomical revision raises a new problem of junior homonym since the type species of Laxaspis is L. qujingensis. Here, we describe some new materials of ‘Dongfangaspis qujingensis’ and Damaspis vartus from the Xishancun Formation (early Lochkovian, Early Devonian) in Qujing, Yunnan Province. ‘Dongfangaspis qujingensis’ strikingly resembles Damaspis vartus in the slightly longer headshield, bifurcated ends of the lateral transverse canals, unconnected V-shaped posterior supraorbital canals, and at least seven pairs of lateral transverse canals issuing from the lateral dorsal canal. These similarities indicate that ‘D. qujingensis’ is more suggestive of Damaspis than Dongfangaspis and Laxaspis. Therefore, we propose to remove ‘Dongfangaspis qujingensis’ from Laxaspis to Damaspis. The new specimens of Damaspis vartus reveal five long lateral transverse canals on the right side, corroborating that the asymmetric sensory canal system in the holotype is the intraspecific variation.

Morphometric analysis of the cervical vertebral series in extant birds with implications for Mesozoic avialan feeding ecology

LIU Bi-Ying, Thomas A. STIDHAM, WANG Xiao-Ping, LI Zhi-Heng, ZHOU Zhong-He

2024, 62(2):  99-119.  DOI: 10.19615/j.cnki.2096-9899.240305

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The inference of Mesozoic avialan bird diets previously relied on traditional methods such as morphological comparisons among taxa and direct evidence such as identifiable stomach contents. However, the application of these approaches has been limited because of uncommon preservation of relevant fossil evidence. We searched for additional informative characteristics to help develop new methods to assess the diet of fossil birds. In particular, the morphology of the avialan neck is highly modularized and plays roles in multiple functions including food acquisition. The structure of and variation among the cervical vertebrae likely reflects the demands of feeding ecology in fossil and extant birds because the avialan neck evolved to, at least in part, replace the forelimbs by assisting with activities such as cranioinertial feeding and other ecological functions. Here, we utilize morphometric and statistical analyses to establish an initial quantitative relationship between cervical morphology and dietary modes in both extant and extinct birds. This morphometric framework derived from the cervical morphology of living birds is used as a basis to estimate the diet categories of five taxa of Mesozoic birds. The results indicate that there is a quantitative correlation between cervical morphology differentiation and their interrelated feeding modes. The enantiornithine taxa examined exhibit cervical morphologies similar to extant insectivorous or carnivorous birds. The ornithurine species show cervical morphologies that are more aligned with generalist or herbivorous birds, and exhibit preliminary morphological features tied to aquatic adaptions. These findings are consistent in part with other direct fossil evidence, as well as hypotheses developed from other skeletal comparisons. Therefore, the cervical vertebral series, as a skeletal system closely linked to food acquisition, can serve as one of the valuable metrics to provide information for inferring the diet of long extinct Mesozoic birds.

First histochemical examination of a Miocene ostrich eggshell with the oldest mineral-bound peptides

WU Qian, PAN Yan-Hong, LI Zhi-Heng, ZHOU Zhong-He, Alida M. BAILLEUL

2024, 62(2):  120-134.  DOI: 10.19615/j.cnki.2096-9899.240329

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Because ancient proteins have a higher preservation potential than ancient DNA, proteomic studies can help shed light on the biology of some extinct biological groups that are beyond the reach of the field of ancient DNA. The oldest peptide discovered so far is part of the protein struthiocalcin (SCA-1) involved in eggshell mineralization and found within an ostrich egg from the Late Miocene Linxia Basin of Northwest China. It was originally hypothesized that SCA-1 was evenly distributed within the eggshell and was able to enter the fossil record for so long, because it was bound to calcite crystals. We conducted histological, scanning electron microscopy and Raman spectroscopic analyses on this same fossil egg to test if any protein or organic matter could be observed within specific regions of the eggshell and indeed bound to calcite crystals. Our results show that the eggshell is made entirely of calcite except at the base layer, which is made of mammillary knobs at least partially made of apatite. These knobs were secondarily phosphatized during diagenesis. After decalcification of this material, the fossilized mammillary knobs showed fibrous residues consistent in location and morphology with remnants of original organic material forming a network. This network was similar to the organic matrix observed in an extant ostrich eggshell with this same method. The results here suggest that SCA-1 may have been concentrated at the mammillary knobs, rather than evenly throughout the eggshell. Phosphatization may be another taphonomic process that favors organic preservation in deep-time. The paleoclimate and taphonomic environment of the Linxia Basin may have provided favorable conditions for the molecular preservation of this egg. More in-depth histochemical and mineralogical analyses will certainly increase our understanding of organic and ancient protein preservation in this basin.

First report of Hispanodorcas from the Late Miocene of China

WU Yong, WANG Shi-Qi, LIANG Zhi-Yong, GUO Ding-Ge, SUN Bo-Yang, LIU Long, DUAN Kai, CHEN Guo-Zhong

2024, 62(2):  135-155.  DOI: 10.19615/j.cnki.2096-9899.240123

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As a small to middle-sized bovid, Hispanodorcas had previously only been found in the pan-Mediterranean region and South Asia. Its taxonomic classification at the tribe level has been a subject of debate, with possible associations to Antilopini, Reduncini, or Oiocerini. Here, we report on the first discovery of Hispanodorcas in East Asia, H. longdongica sp. nov. from the Daidian Locality in China, dating to the early Baodean age (~8-7 Ma). The new material consists of five skulls with varying states of preservation and provides the most complete osteological information on Hispanodorcas to date. It features a long, slender, and posteriorly curved horncore with a weak homonymous twist and both laterodorsal and medioventral grooves, which is characteristic of Hispanodorcas. This new species is characterized by having the smallest size amongst all known Hispanodorcas species, a weakly curved brain case in the facial region, and poorly developed posterior and anterior basilar tuberosities. These primitive characteristics suggest that H. longdongica may represent an early evolutionary stage of this genus. Furthermore, they indicate that Hispanodorcas might have directly evolved from the Gazella stock. The homonymous twist in the horncore, which aligns with Oiocerini, may be a case of homoplasy.

A possible new amphicyonid from the Miocene of the Linxia Basin

JIANGZUO Qi-Gao, GAO Yuan, Alberto VALENCIANO, LU Dan, WANG Shi-Qi

2024, 62(2):  156-164.  DOI: 10.19615/j.cnki.2096-9899.240320

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Here we report a new form of amphicyonid from an uncertain locality in the Linxia Basin. The derived dental traits imply an affinity to Magericyon, previously known from Europe and possibly southern Asia. The specimen suggests a higher diversity of amphicyonids in eastern Asia than previously thought, and more discovery with stratigraphic information will be needed to elucidate the evolution of Amphicyonidae in eastern Asia.