Earliest siphuncle-bearing cephalopod from the early Cambrian

Recent cephalopods are the most intelligent invertebrates and are unique among molluscs in possessing chambered, gas-filled shells penetrated lengthwise by a siphuncle that regulates buoyancy, enabling their nektonic and predatory lifestyle through jet propulsion. The origin of this key innovation remains enigmatic, as there is a major gap between the earliest known cephalopod, Plectronoceras cambria from the late Cambrian, and molecular clock estimates that place the lineage’s divergence from other molluscs in the early Cambrian. Here we report Eosceras shaanxienses gen. et. sp. nov., a millimetre-scale cephalopod with orthoconic shell from the Shuijingtuo Formation (Cambrian Stage 3) of South China. Internally, the shell exhibits multiple septa and a peripherally situated segmented tube that appears to bridge the septa through minute canals, indicating that the soft body migrated anteriorly to form successive chambers during growth while maintaining contact with earlier chambers ..., , # Earliest siphuncle-bearing cephalopod from the early Cambrian

Dataset DOI: [10.5061/dryad.qbzkh18zk](https://doi.org/10.5061/dryad.qbzkh18zk)

## Description of the data and file structure

Micro-CT scanning data was performed on specimens CUBar297 (GQ-LYB-4)-1(**20231122_gjf_Bar297-1_3.72um-tiff.zip**), CU(CT-eosceras)-7(**20260106_gjf_cupi-7_2.72um_tiff.zip**) and CU(CT-eosceras)-11(**20260107_gjf_cupi-11_2.04um_tiff.zip**) with the Zeiss Xradia 520 system at the State Key Laboratory of Continental Dynamics of Northwest University in Xi’an, Shaanxi Province, China.

Scanning conditions were 40 kV accelerating voltage, 80 μA beam current, and an isotropic voxel size of 3.72 μm, 2.72 μm and 2.04 μm, respectively. Approximately 1,000 projection images were acquired in TIFF format. Data were reconstructed using standard, filtered back-projection algorithms and visualized in VG Studio Max 2.2 for three-dimensional volume rendering and segmentation.

## Code/software

VG Studio Max 2.2
, ,

现生头足类（cephalopod）是最具智慧的无脊椎动物，在软体动物中独树一帜，其拥有分室充气的壳体，壳体纵向贯穿有调控浮力的体管（siphuncle），借此可通过喷水推进实现自游和掠食性生活方式。
这一关键创新的起源至今仍成谜：目前已知最古老的头足类是产自晚寒武世的三叶角石（Plectronoceras cambria），而分子钟估算显示该类群与其他软体动物的分化发生在早寒武世，二者之间存在巨大的时间断层。
本文报道产自中国南方水井沱组（寒武纪第3阶）的毫米级直壳头足类新属新种陕西始角石（Eosceras shaanxienses gen. et sp. nov.）。该壳体内部可见多个隔壁，以及位于周缘的分节状管结构，该结构通过微细管道连接相邻隔壁，表明生长过程中软体组织向前迁移以形成新的分室，同时仍与早期分室保持连通……# 早寒武世已知最早具体管的头足类

数据集DOI: [10.5061/dryad.qbzkh18zk](https://doi.org/10.5061/dryad.qbzkh18zk)

## 数据与文件结构说明

本研究在中国陕西省西安市西北大学大陆动力学国家重点实验室，使用Zeiss Xradia 520型系统对标本CUBar297 (GQ-LYB-4)-1（**20231122_gjf_Bar297-1_3.72um-tiff.zip**）、CU(CT-eosceras)-7（**20260106_gjf_cupi-7_2.72um_tiff.zip**）及CU(CT-eosceras)-11（**20260107_gjf_cupi-11_2.04um_tiff.zip**）开展了显微CT扫描。

扫描参数为：加速电压40 kV，束流80 μA，各标本的各向同性体素尺寸分别为3.72 μm、2.72 μm及2.04 μm。共获取约1000张TIFF格式的投影图像。数据采用标准滤波反投影算法进行重建，并通过VG Studio Max 2.2软件进行三维体绘制与分割可视化。

## 代码与软件

VG Studio Max 2.2