Related Experiment Video
Updated: Jul 6, 2025
10:09
Sample Preparation Method of Scanning and Transmission Electron Microscope for the Appendages of Woodboring Beetle
Published on: February 3, 2020
18.9K
A giant stem-group chaetognath
Tae-Yoon S Park1,2, Morten Lunde Nielsen1,3,4, Luke A Parry5
1Division of Earth Sciences, Korea Polar Research Institute, 26 Songdomirae-ro Yeonsu-gu, Incheon 21990, Republic of Korea.
Science Advances
|January 3, 2024
Summary
A new fossil, *Timorebestia koprii*, from the Cambrian Sirius Passet Lagerstätte, reveals early chaetognaths were large pelagic predators. Its unique features confirm its position on the chaetognath stem, suggesting a higher trophic role in ancient marine ecosystems.
Area of Science:
- Paleontology
- Evolutionary Biology
- Marine Biology
Background:
- Chaetognaths, or arrow worms, are ancient pelagic predators dating back to the Cambrian period.
- Previous interpretations of related fossils like *Amiskwia sagittiformis* were uncertain regarding their phylogenetic placement.
- Understanding early chaetognath evolution is key to reconstructing ancient marine food webs.
Purpose of the Study:
- To describe a new large stem chaetognath fossil, *Timorebestia koprii*, from the lower Cambrian Sirius Passet Lagerstätte.
- To determine the phylogenetic position of *T. koprii* within the chaetognath lineage.
- To infer the ecological role of early chaetognaths in Cambrian marine ecosystems.
Main Methods:
- Fossil description and morphological analysis of *Timorebestia koprii*.
- Comparative anatomy with known chaetognaths and related taxa.
- Phylogenetic analysis based on shared anatomical features, particularly the ventral ganglion.
Main Results:
- *Timorebestia koprii* is described with features including lateral and caudal fins, antennae, and a jaw apparatus.
- The presence of a shared ventral ganglion firmly places *T. koprii* on the chaetognath stem lineage.
- The large size and gut contents indicate early chaetognaths were significant predators.
Conclusions:
- *Timorebestia koprii* represents a large, early chaetognath, expanding our understanding of their ancestral morphology.
- This discovery solidifies the phylogenetic position of certain Cambrian fossils within the chaetognath stem group.
- Early chaetognaths likely occupied a more dominant predatory role in Cambrian pelagic ecosystems than their modern counterparts.
Related Concept Videos
02:05Prochirality
3.8K
The concept of prochirality leads to the nomenclature of the individual faces of a molecule and plays a crucial role in the enantioselective reaction. It is a concept where two or more achiral molecules react to produce chiral products. A typical process is the reaction of an achiral ketone to generate a chiral alcohol. Here, the achiral reactant reacts with an achiral reducing agent, sodium borohydride, to generate an equimolar mixture of the chiral enantiomers of the product. For example, an...
3.8K
01:15Teeth
431
The formation of teeth, also known as odontogenesis, is a complex process that begins in utero, around the sixth week of embryonic development. There are three stages to this process: the bud stage, the cap stage, and the bell stage.
In the bud stage, the tooth germ (an aggregation of cells) starts to form in the developing jawbone. During the cap stage, the tooth germ differentiates into enamel organ, dental papilla, and dental sac, which will later develop into the tooth's enamel, dentin...
In the bud stage, the tooth germ (an aggregation of cells) starts to form in the developing jawbone. During the cap stage, the tooth germ differentiates into enamel organ, dental papilla, and dental sac, which will later develop into the tooth's enamel, dentin...
431
01:07Radicals: Electronic Structure and Geometry
4.0K
This lesson delves into the geometry of a radical, which is influenced by the electronic structure of the molecule. The principle is similar to that of a lone pair, where the unpaired electron influences the geometry at the radical center.
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
4.0K
03:21Phylogenetic Trees
45.3K
Phylogenetic trees come in many forms. It matters in which sequence the organisms are arranged from the bottom to the top of the tree, but the branches can rotate at their nodes without altering the information. The lines connecting individual nodes can be straight, angled, or even curved.
45.3K
01:31Taxonomy
74.4K
Taxonomy is the science of defining and naming groups of biological organisms based on shared characteristics. It uses a hierarchy of increasingly inclusive categories with Latin names. The smallest units of taxonomy, species and genus, are used to assign a formal, taxonomic name to each species in a system. This classification system, referred to as binomial nomenclature, was formalized by Carolus Linnaeus in the 18th century.
Hierarchy of Taxonomy
The hierarchy that Carolus Linnaeus first...
Hierarchy of Taxonomy
The hierarchy that Carolus Linnaeus first...
74.4K
01:23Phylogeny
44.2K
Phylogeny is concerned with the evolutionary diversification of organisms or groups of organisms. A group of organisms with a name is called a taxon (singular). Taxa (plural) can span different levels of the evolutionary hierarchy. For instance, the group containing all birds is a taxon (comprising the class Aves), and the group of all species of daisies (the genus Bellis) is a taxon. Phylogenies can likewise include just one genus (i.e., depict species relationships) or span an entire kingdom.
44.2K