Chia-Hsin Hsu - Research

Starting from echinoids, my research has expanded to crinoids, mollusks, sponges, fishes, deers... By building fossil records and analysing palaeontological data, I explore how life’s evolution links to geological dynamics and changing palaeoenvironments.

I use echinoids as a model system to evaluate patterns of morphological and life-mode change through geological time, and to understand the potential controlling factors driving these changes. For regions with well-studied fossil records (Mesozoic Euroamerica), I am building a specimen-based dataset and utilising statistical modelling and disparity analytical methods to quantify morphological and life-mode dynamics among echinoid lineages and communities. For regions with underexplored fossil records (Cenozoic Asia), I describe new fossils and aim to resolve the missing pieces of their evolutionary history and to provide a baseline for Anthropocene environemntal changes.

Mesozoic Echinoids

Cenozoic Echinoids

source: PBDB

Part 1. Mesozoic Echinoids

(1) Within lineage morphological evolution of bizarre holasteroid echinoids

The Infulaster–Hagenowia lineage consists of fossil echinoids dominant in the Cretaceous of Europe. Its gradually slender rostrum and decreasing size represent one of the most bizarre and classic anagenetic evolutionary sequences among animals. To understand the potential drivers of these changes, I evaluate their trait evolution using likelihood-based modelling methods, aiming to contribute to ongoing discussions on the mechanisms of anagenetic speciation.

Hsu et al. in prep

(2) Morphological and ecological evolution of British Cretaceous echinoids

Morphospace and ecospace are widely used to quantify changes in animal shape and modes of life, yet whether they reflect genuine evolutionary signals or biases in the rock record is often underestimated. The British Cretaceous echinoids represent one of the best-studied regional fossil datasets, with 229 species and more than 10,000 specimens housed in British museums. This high-resolution dataset provides an excellent opportunity to evaluate this issue. By identifying overall morphospace and ecospace patterns and comparing them with regional signals, this research aims to clarify the controlling factors of these changes and to seek a true scenario of the macroevolutionary history of Cretaceous echinoids, a time when echinoids rapidly diversified and reached their diversity peak.

Hsu et al. in prep

Part 2. Cenozoic Echinoids

(1) Spatangoid echinoids and Taiwan's orogeny

The new fossil spatangoid assemblages genuinely record the orogenic and metamorphic history of Taiwan. The same genera of fossil echinoids found in both Oligocene slate strata and Pleistocene mudstone strata correlate with the metamorphic history of the rocks. The north-to-south migration of these echinoids corresponds to the earlier uplift of northern Taiwan, with southern Taiwan acting as a refuge for mud-dwelling echinoids.

Hsu et al. 2024 Geobios

(2) Spatangoid echinoids and Tethys Palaeobiogeography

The new fossil species Faorina mizoramensis Hsu & Lin 2026, from the Miocene of India, resolves the mystery that fossil Faorina were previously known only from the Mediterranean, whereas extant Faorina are restricted to the Indo–West Pacific. This indicates that Faorina once had a wider distribution. Following the closure of the Tethys Seaway, Mediterranean populations eventually went regionally extinct, with the Indo–West Pacific acting as a refuge for the lineage.

Hsu et al. 2026 Zoological Studies

(3) Spatangoid echinoids and petal evolution

Living deep within seafloor sediments is challenging because oxygen is scarce. However, heart urchins thrive there, thanks to their specialized respiratory structures (aka petals). To understand how they adapted to this lifestyle, we studied Brissopsis, one of the most successful genera of deep-burrowing heart urchins. We report new fossils from the Pliocene of the Philippines and the Plio-Pleistocene of Taiwan, filling important gaps in the fossil record of Brissopsis. We then compiled available records and analysed petal shapes using outline-based geometric morphometrics. Our results suggest that diverse petal morphologies arose early in Brissopsis evolutionary history. This diversity may have supported different respiratory strategies and niche partitioning, helping Brissopsis colonize diverse seafloor environments and contributing to its evolutionary success!