Phylogeny, ecology and deep time: 2D outline analysis of anuran skulls from the Early Cretaceous to the Recent

Stratiomyomorpha (soldier flies and allies) is an ingroup of Diptera, with a fossil record stretching back to the Early Cretaceous (the Barremian, about 125 MYA). Stratiomyomorpha includes at least 3,000 species in the modern fauna, with many species being crucial for ecosystem functions, especially as saprophages. Larvae of many stratiomyomorphans are especially important as scavengers and saproxyls in modern ecosystems. Yet, fossil larvae of the group are extremely scarce. Here we present 23 new records of fossil stratiomyomorphan larvae, representing six discrete morphotypes. Specimens originate from Cretaceous amber from Myanmar, Eocene Baltic amber, Miocene Dominican amber, and compression fossils from the Eocene of Messel (Germany) and the Miocene of Slovenia. We discuss the implications of these new records for our understanding of stratiomyomorphan ecomorphology in deep time as well as their palaeoecology.

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Nuclear preservation in the cartilage of the Jehol dinosaur Caudipteryx

Communications Biology ◽

10.1038/s42003-021-02627-8 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Xiaoting Zheng ◽

Alida M. Bailleul ◽

Zhiheng Li ◽

Xiaoli Wang ◽

Zhonghe Zhou

Keyword(s):

Early Cretaceous ◽

Late Cretaceous ◽

Northeast China ◽

Jehol Biota ◽

Deep Time ◽

Dna Preservation ◽

Hematoxylin And Eosin ◽

Vertebrate Tissue

AbstractPrevious findings on dinosaur cartilage material from the Late Cretaceous of Montana suggested that cartilage is a vertebrate tissue with unique characteristics that favor nuclear preservation. Here, we analyze additional dinosaur cartilage in Caudipteryx (STM4-3) from the Early Cretaceous Jehol biota of Northeast China. The cartilage fragment is highly diagenetically altered when observed in ground-sections but shows exquisite preservation after demineralization. It reveals transparent, alumino-silicified chondrocytes and brown, ironized chondrocytes. The histochemical stain Hematoxylin and Eosin (that stains the nucleus and cytoplasm in extant cells) was applied to both the demineralized cartilage of Caudipteryx and that of a chicken. The two specimens reacted identically, and one dinosaur chondrocyte revealed a nucleus with fossilized threads of chromatin. This is the second example of fossilized chromatin threads in a vertebrate material. These data show that some of the original nuclear biochemistry is preserved in this dinosaur cartilage material and further support the hypothesis that cartilage is very prone to nuclear fossilization and a perfect candidate to further understand DNA preservation in deep time.

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A Cretaceous peak in family-level insect diversity estimated with mark–recapture methodology

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2019.2054 ◽

2019 ◽

Vol 286 (1917) ◽

pp. 20192054 ◽

Cited By ~ 6

Author(s):

Sandra R. Schachat ◽

Conrad C. Labandeira ◽

Matthew E. Clapham ◽

Jonathan L. Payne

Keyword(s):

Early Cretaceous ◽

Taxonomic Diversity ◽

Mass Extinctions ◽

Time Intervals ◽

Mark Recapture ◽

Deep Time ◽

Steep Increase ◽

Family Level ◽

History Of ◽

Uneven Sampling

The history of insects’ taxonomic diversity is poorly understood. The two most common methods for estimating taxonomic diversity in deep time yield conflicting results: the ‘range through’ method suggests a steady, nearly monotonic increase in family-level diversity, whereas ‘shareholder quorum subsampling’ suggests a highly volatile taxonomic history with family-level mass extinctions occurring repeatedly, even at the midpoints of geological periods. The only feature shared by these two diversity curves is a steep increase in standing diversity during the Early Cretaceous. This apparent diversification event occurs primarily during the Aptian, the pre-Cenozoic interval with the most described insect occurrences, raising the possibility that this feature of the diversity curves reflects preservation and sampling biases rather than insect evolution and extinction. Here, the capture–mark–recapture (CMR) approach is used to estimate insects’ family-level diversity. This method accounts for the incompleteness of the insect fossil record as well as uneven sampling among time intervals. The CMR diversity curve shows extinctions at the Permian/Triassic and Cretaceous/Palaeogene boundaries but does not contain any mass extinctions within geological periods. This curve also includes a steep increase in diversity during the Aptian, which appears not to be an artefact of sampling or preservation bias because this increase still appears when time bins are standardized by the number of occurrences they contain rather than by the amount of time that they span. The Early Cretaceous increase in family-level diversity predates the rise of angiosperms by many millions of years and can be better attributed to the diversification of parasitic and especially parasitoid insect lineages.

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Applying Oxygen Isotope Paleothermometry in Deep Time

The Paleontological Society Papers ◽

10.1017/s1089332600002540 ◽

2012 ◽

Vol 18 ◽

pp. 39-68 ◽

Cited By ~ 20

Author(s):

Ethan L. Grossman

Keyword(s):

Oxygen Isotope ◽

Early Cretaceous ◽

Trace Element Analysis ◽

Oxygen Isotopic Composition ◽

Future Research ◽

Element Analysis ◽

Ambient Seawater ◽

Deep Time ◽

Clumped Isotope ◽

Isotope Equilibrium

Oxygen isotope paleotemperature studies of the Mesozoic and Paleozoic are based mainly on conodonts, belemnite guards, and brachiopod shells—material resistant to diagenesis and generally precipitated in oxygen isotope equilibrium with ambient water. The greatest obstacle to accurate oxygen isotope paleothermometry in deep time is uncertainty in the oxygen isotopic composition of the ambient seawater. The second greatest obstacle is fossil diagenesis. Useful application of the oxygen isotope method to brachiopod shells requires extreme care in sample screening and analyses, and is best done with scanning-electron microscopy, and petrographic and cathodoluminescence microscopy, and trace-element analysis. Correct interpretation of oxygen isotope data is greatly aided by thorough understanding of the paleolatitude, paleoecology, and depositional environment of the samples. The oxygen isotope record for the Triassic, based on brachiopod shells, is too sparse to show any distinct isotopic features. Jurassic and Early Cretaceous δ18O records, based on belemnites, show a Toarcian (Jurassic) decline (warming), a Callovian-Oxfordian acme, and an Early Cretaceous increase (cooling) to a Valanginian-Hauterivian maximum, followed by a decline (warming) to a middle Barremian minimum. Deep-time applications to oxygen isotope thermometry provide evidence for cooling and glaciation in the Ordovician, Carboniferous, and Permian. The δ18O values from Silurian and Devonian brachiopod shells and conodonts average lower than those of the remaining Phanerozoic because of the absence of continental glaciers and possibly higher temperatures (~37°?), although slightly lower (≤2%o) seawater δ18O cannot be ruled out. The hypothesis of high temperatures in the early Paleozoic implies a relatively constant hydrospheric δ18O, which is supported by clumped isotope paleotemperatures. However, more research is needed to develop methods for evaluating clumped isotope reordering in fossils. Ongoing and future research in oxygen isotope and clumped isotope thermometry hold the promise of resolving deep-time temperatures, seawater δ18O, and salinity with heretofore unavailable accuracy (±2°, ±0.4%o, and ±2 psu), providing the environmental setting for the evolution of metazoan life on Earth.

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