DOI: 10.5061/dryad.p2ngf1w0j
title: An armored, freshwater Lobopodian with chemical defenses from the Carboniferous

description: Lobopodians are an evolutionary grade of panarthropods characterized by
 their vermiform bodies and paired, unjointed lobopodous legs. A
 paraphyletic group, their study is of particular  significance in
 understanding the evolution of extant panarthropods. Found exclusively in
 marine deposits from the Paleozoic, the great majority of species come
 from Cambrian Konservat-Lagerstätten with only a few representatives known
 from the Ordovician, Silurian, and Carboniferous. Here we redescribe
 Palaeocampa anthrax from the Carboniferous Mazon Creek (USA) and
 Montceau-les-Mines (France) Lagerstätten as a lobopodian. First published
 in 1865, nearly fifty years before the discovery of the Burgess Shale,
 Palaeocampa is historically the first discovered lobopod and its presence
 at the slightly younger Montceau-les-Mines (Gzhelian), makes this the
 youngest known fossil ‘xenusiid’ lobopodian species. We present the case
 that Palaeocampa most likely inhabited a freshwater environment,
 contesting the view that Paleozoic lobopodians were exclusively marine.
 Palaeocampa bears biomineralized dorso-lateral and lateral sclerite sets
 with a unique architecture unseen in other lobopodian sclerites, which may
 have been capable of secreting defensive chemicals at their tips.
 Palaeocampa anthrax represents a major evolutionary step in lobopodians,
 both in environmental adaptations and in defensive abilities.
description: A FTIR  with a microscope (Bruker, Vertex v70v and Hyperion 2000)
 was used to measure the spectral reflectivity over the fossil surface in
 the mid Infrared range (wavenumber = 600~4000 cm-1) where the
 vibrational/rotational energy transitions of the major chemical bonds
 correlated with organic molecules centered at. The spectral reflectivities
 qualitatively reveal the presence of molecular bonds and therefore
 differentiate the measured materials by their chemical compositions. Five
 FTIR scans were conducted on different areas containing tip, spine and
 matrix areas of fossil specimen 38032, and four were conducted on specimen
 42834, producing nine scans total. All scans used an aperture of 60 µm,
 and step sizes of these scans ranged from 20-50 µm, for a total of 12175
 individual spectra collected across both fossils. Spectra in which
 multiple category types overlapped were then excluded, resulting in 9114
 individual spectra. Systematic differences between measured values were
 observed between scans for each fossil (Fig. 4), and so individual spectra
 were pre-processed using the Standard Normal Variate (SNV) method of the
 prospectr package, which is a common pre-processing technique for analysis
 of FTIR spectra that removes the multiplicative interferences of scatter
 and particle size, accounting for overall differences in mean values and
 variance between individual spectra by mean centering each spectrum and
 dividing it by its own standard deviation. For graphical analysis and
 subsequent statistical testing, SNV-normalized spectra were smoothed via
 quadratic Savitzky-Golay smoothing as implemented in the ‘savgol’ function
 of the pracma package, using a window size of 25, based on the
 recommendations of for minimizing the likelihood of introducing
 overfitting of narrow peaks during smoothing.
description: # An armored, freshwater Lobopodian with chemical defenses from the
 Carboniferous
 [https://doi.org/10.5061/dryad.p2ngf1w0j](https://doi.org/10.5061/dryad.p2ngf1w0j) ## Description of the data and file structure A FTIR  with a microscope (Bruker, Vertex v70v and Hyperion 2000) was used to measure the spectral reflectivity over the fossil surface in the mid Infrared range (wavenumber = 600~4000 cm-1) where the vibrational/rotational energy transitions of the major chemical bonds correlated with organic molecules centered at. The spectral reflectivities qualitatively reveal the presence of molecular bonds and therefore differentiate the measured materials by their chemical compositions. Five FTIR scans were conducted on different areas containing tip, spine, and matrix areas of fossil specimen 38032, and four were conducted on specimen 42834, producing nine scans total. All scans used an aperture of 60 µm, and step sizes of these scans ranged from 20-50 µm, for a total of 12175 individual spectra collected across both fossils. **Data_S8_Lobopod_fossil_FTIR_CC_NY_data_combined_only60um_aperture_categorized_standardnormalvariate.csv**: Contains the variables used for the analysis. * **Scan_ID**: The file name given to a specific scan. * **Fossil**: Identification of the fossil by specimen number. * **Aperture**: The aperture setting used in that specific scan. * **Step**: The distance of movement used in each scan. * **lx**: The x position according to each y coordinate. * **Ly**: The y position according to each x coordinate. * **X (microns)**: The x distance in microns from the origin point of the scan. * **Y (microns)**: The y distance in microns from the origin point of the scan. * **Matrix**: Indicator if scan was positioned on the matrix of the fossil (1=yes, 0=no). * **Spine**: Indicator if scan was positioned on the spine of the fossil (1=yes, 0=no). * **Tip**: Indicator if scan was positioned on the tip of the spine of the fossil (1=yes, 0=no). * **Category**: IS a designator assigning the scan to which part of the fossil is being examined (matrix, spine, or tip). \** All other headings refer to the Infrared wavelength, and the respective results are the spectral reflectivity. **Data_S9_Lobopod_fossil_FTIR_CC_NY_data_combined_only60um_aperture_categorized.csv**: Contains the variables used for the analysis. * **Scan_ID**: The file name given to a specific scan. * **Fossil**: Identification of the fossil by specimen number. * **Aperture**: The aperture setting used in that specific scan. * **Step**: The distance of movement used in each scan. * **lx**: The x position according to each y coordinate. * **Ly**: The y position according to each x coordinate. * **X (microns)**: The x distance in microns from the origin point of the scan. * **Y (microns)**: The y distance in microns from the origin point of the scan. * **Matrix**: Indicator if scan was positioned on the matrix of the fossil (1=yes, 0=no). * **Spine**: Indicator if scan was positioned on the spine of the fossil (1=yes, 0=no). * **Tip**: Indicator if scan was positioned on the tip of the spine of the fossil (1=yes, 0=no). * **Category**: IS a designator assigning the scan to which part of the fossil is being examined (matrix, spine, or tip). \** All other headings refer to the Infrared wavelength, and the respective results are the spectral reflectivity. **Data_S10_Lobopod_fossil_FTIR_CC_NY_data_combined_only60um_aperture.csv**: Contains the variables used for the analysis. * **Scan_ID**: The file name given to a specific scan. * **Fossil**: Identification of the fossil by specimen number. * **Aperture**: The aperture setting used in that specific scan. * **Step**: The distance of movement used in each scan. * **lx**: The x position according to each y coordinate. * **Ly**: The y position according to each x coordinate. * **X (microns)**: The x distance in microns from the origin point of the scan. * **Y (microns)**: The y distance in microns from the origin point of the scan. * **Matrix**: Indicator if scan was positioned on the matrix of the fossil (1=yes, 0=no). * **Spine**: Indicator if scan was positioned on the spine of the fossil (1=yes, 0=no). * **Tip**: Indicator if scan was positioned on the tip of the spine of the fossil (1=yes, 0=no). * **Category**: IS a designator assigning the scan to which part of the fossil is being examined (matrix, spine, or tip). \**All other headings refer to the Infrared wavelength, and the respective results are the spectral reflectivity. **Note**: Any extra information needed on the above files/scans or software/hardware used in the processing of this data can be found by sending a request to the Yu Lab at Columbia University in the Department of Applied Physics and Mathematics, [ny2214@columbia.edu](mailto:ny2214@columbia.edu).