Deep Divisions in the Tree of Life--What Does the Fossil Record Reveal?

J. W. Schopf

doi:10.2307/1542968

Flying rocks and flying clocks: disparity in fossil and molecular dates for birds

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2014.0677 ◽

2014 ◽

Vol 281 (1788) ◽

pp. 20140677 ◽

Cited By ~ 25

Author(s):

Daniel T. Ksepka ◽

Jessica L. Ware ◽

Kristin S. Lamm

Keyword(s):

Analytical Methods ◽

Fossil Record ◽

Tree Of Life ◽

Temporal Information ◽

Molecular Dating ◽

Critical Nodes ◽

Molecular Divergence ◽

Divergence Dates ◽

Divergence Estimates ◽

Age Estimates

Major disparities are recognized between molecular divergence dates and fossil ages for critical nodes in the Tree of Life, but broad patterns and underlying drivers remain elusive. We harvested 458 molecular age estimates for the stem and crown divergences of 67 avian clades to explore empirical patterns between these alternate sources of temporal information. These divergence estimates were, on average, over twice the age of the oldest fossil in these clades. Mitochondrial studies yielded older ages than nuclear studies for the vast majority of clades. Unexpectedly, disparity between molecular estimates and the fossil record was higher for divergences within major clades (crown divergences) than divergences between major clades (stem divergences). Comparisons of dates from studies classed by analytical methods revealed few significant differences. Because true divergence ages can never be known with certainty, our study does not answer the question of whether fossil gaps or molecular dating error account for a greater proportion of observed disparity. However, empirical patterns observed here suggest systemic overestimates for shallow nodes in existing molecular divergence dates for birds. We discuss underlying biases that may drive these patterns.

Download Full-text

Cretophengodidae, a new Cretaceous beetle family, sheds light on the evolution of bioluminescence

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2020.2730 ◽

2021 ◽

Vol 288 (1943) ◽

pp. 20202730

Author(s):

Yan-Da Li ◽

Robin Kundrata ◽

Erik Tihelka ◽

Zhenhua Liu ◽

Diying Huang ◽

...

Keyword(s):

Fossil Record ◽

Historical Biogeography ◽

Tree Of Life ◽

Light Organ ◽

Defensive Function ◽

Stem Group

Bioluminescent beetles of the superfamily Elateroidea (fireflies, fire beetles, glow-worms) are the most speciose group of terrestrial light-producing animals. The evolution of bioluminescence in elateroids is associated with unusual morphological modifications, such as soft-bodiedness and neoteny, but the fragmentary nature of the fossil record discloses little about the origin of these adaptations. We report the discovery of a new bioluminescent elateroid beetle family from the mid-Cretaceous of northern Myanmar ( ca 99 Ma), Cretophengodidae fam. nov. Cretophengodes azari gen. et sp. nov. belongs to the bioluminescent lampyroid clade, and would appear to represent a transitional fossil linking the soft-bodied Phengodidae + Rhagophthalmidae clade and hard-bodied elateroids. The fossil male possesses a light organ on the abdomen which presumably served a defensive function, documenting a Cretaceous radiation of bioluminescent beetles coinciding with the diversification of major insectivore groups such as frogs and stem-group birds. The discovery adds a key branch to the elateroid tree of life and sheds light on the evolution of soft-bodiedness and the historical biogeography of elateroid beetles.

Download Full-text

It's a protist-eat-protist world: recalcitrance, predation, and evolution in the Tonian–Cryogenian ocean

Emerging Topics in Life Sciences ◽

10.1042/etls20170145 ◽

2018 ◽

Vol 2 (2) ◽

pp. 173-180 ◽

Cited By ~ 12

Author(s):

Phoebe A. Cohen ◽

Leigh Anne Riedman

Keyword(s):

Molecular Clock ◽

Fossil Record ◽

Critical Role ◽

Indirect Evidence ◽

Tree Of Life ◽

Current Understanding ◽

Evolutionary Transitions ◽

Ecological Interaction ◽

Fossil Evidence ◽

Multiple Metrics

Predation, and how organisms respond to it, is an important ecological interaction across the tree of life. Much of our understanding of predation focuses on modern metazoa. However, predation is equally important in single-celled eukaryotes (commonly referred to as protists). In the fossil record, we see evidence of protists preying on other protists beginning in the Tonian Period (1000–720 Ma). In addition, the first evidence of eukaryotic biomineralization and the appearance of multiple unmineralized but recalcitrant forms are also seen in the Tonian and Cryogenian (720–635 Ma), potentially indirect evidence of predation. This fossil evidence, coupled with molecular clock analyses, is coincident with multiple metrics that show an increase in the diversity of eukaryotic clades and fossil assemblages. Predation, thus, may have played a critical role in the diversification of eukaryotes and the evolution of protistan armor in the Neoproterozoic Era. Here, we review the current understanding of predation in the Tonian and Cryogenian oceans as viewed through the fossil record, and discuss how the rise of eukaryotic predation upon other eukaryotes (eukaryovory) may have played a role in major evolutionary transitions including the origins of biomineralization.

Download Full-text