Tracking Ancient Life

Dr Liam Herringshaw

lgh865@hotmail.com

Key terms

Bioturbation

Ichnology

(ichnos, Greek: footprint, track, trail)

Trace Fossils

1. What are trace fossils?

Sedimentary structures produced by life- Burrows, borings, tracks, trails, roots...

...and dung!

The Lloyds Bank coprolite

Why they matter

• Fossil record of behaviour

• Fossil record of soft-bodied organisms

• Organism-environment interactions

• Ecological niche creation

• Nutrient flux

• Taphonomy

Luminous lugworm

UniformitarianismThe present is the key

to the past

Ichnological principles

1. Same organism; different traces

Arthropod trace fossils

Ichnological principles

2. Different organisms; same traces

Annelid wormsSea anemones

Phoronids

Ichnological principles

3. Same trace; different preservation

2. Traces of Yorkshire

What trace fossils does the museum have?

3. Common trace fossils

(Burrows, trails; mostly marine)

Ichnotaxonomy

N.B. Names are for trace fossil only, not organism that made the structure

Planolites

SkolithosSkolithos

Thalassinoides

Thalassinoides tracemaker?

Chondrites

OphiomorphaOphiomorpha

OphiomorphaOphiomorpha tracemaker? tracemaker?

Rhizocorallium

Rusophycus

Rusophycus tracemaker?

Trace fossil?

Impression of a jellyfish?

Or a sand volcano?

Not trace fossils

Shrinkage cracks

Flute castsFlute casts

Not trace fossilsNot trace fossils

Hand Specimens:What Have You Got?

4. The Fossil Record of Behaviour

Earliest animals?

565 Ma locomotion trails,Newfoundland:

Liu et al. (2010)http://geology.gsapubs.org/content/38/2/123.abstract

Ediacaran-CambrianEdiacaran-Cambrianboundaryboundary

Cambrian complexity

The Cambrian Explosion

Seilacher & Pfluger (1994)

Onshore to offshore

Colonization of landColonization of land

Plant Trace Fossils

Becoming upright

Trackway analysis shows tetrapods become bipedal in early Triassic

Kubo & Benton (2009)

http://onlinelibrary.wiley.com/doi/10.1111/j.1475-4983.2009.00897.x/full

The speed of dinosaurs

5. The speed of dinosaurs?

• Type of footprint?

• Footprint size?

• Animal size?

• Stride length?

• Speed?

• Behaviour?

Calculating trackmaker speed

v = 0.25*g0.5*SL1.67*h-1.17

Or, more simply:

Hip height = 4 x footprint length

Stride length/ hip height = speed

(<2 = walking, >3 = running)

Sheffield Geology Group – dinosaur speed calculator:http://www.sorbygeology.group.shef.ac.uk/DINOC01/dinocal1.html

Useful links

www.fossilhub.org