Trace-Fossil Systematics - Trace Fossils as Indicators of Sedimentary Environments - page 91

2020

2010

2000

1990

1980

Häntzschel (1975)

1970

Häntzschel (1962)
ICZN (1961)

1960

1950

World War II

1940

1930

1920

World War I

1910

1900

Fuchs (1895)

1890

Nathorst (1881)

1880

1870

1860 Hitchcock (1858)

Protichnites Owen, 1852

1850

Gordia Emmons, 1844

1840

Entobia Bronn, 1837

Chondrites von Sternberg, 1833

1830

Asteriacites von Schlotheim, 1820

1820

0 5 10 15 20 25

Number of Valid Ichnogenera ( n = 585)

Burrows Bioerosion trace fossils Trackways Imprints Trails

FIGURE 7 Cross plot of the number of valid invertebrate ichnogenera erected over time ( n ¼ 585)
as included in this database and published until 2011 (inclusive), subdivided into different trace-
fossil groups. The introduction of the first trace fossil in each category is highlighted, and major
events and publications with an impact on ichnotaxonomy are indicated.

3.3 Data Analysis
Figure 7 displays a graph indicating the number of invertebrate ichnogenera
erected each year ( n

585), as included in this database and published until end
of 2011, with some interesting trends worthy of note. Since the erection of Aster-
iacites vonSchlotheim, 1820as the first valid ichnogenus (but see thediscussionby
Schlirf, 2012 ), a considerable number of ichnotaxa was introduced as presumed
body fossils (mainly seaweeds, e.g., fucoids) during the nineteenth century. Their
interpretation as trace fossils by Nathorst (1881) was slowly accepted by
contemporaneous researchers but became more accepted after the comprehensive
work done by Fuchs (1895) . This change in paradigm seems to be the reason for a
considerably reduced activity in the introduction of new ichnotaxa until the 1960s.
Furthermore, this trend was influenced by the two world wars and the post-World
War II situation, with periods of very restricted ichnotaxonomical work.

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