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AN ARAUCARIAN CONIFER BRACT-SCALE COMPLEX FROM THE LOWER JURASSIC OF MASSACHUSETTS: IMPLICATIONS FOR ESTIMATING PHYLOGENETIC AND STRATIGRAPHIC CONGRUENCE IN THE ARAUCARIACEAE

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The conifer family Araucariaceae has an extensive Mesozoic fossil record, but no unambiguous megafossils of this group have been described from the Newark Super-group of eastern North America. A bract-scale complex attributable to Araucaria is described from the Lower Jurassic Portland Formation of Massachusetts. Although known from a single specimen, this discovery is significant as the first bona fide megafossil of the Araucariaceae from the Newark Supergroup and one of the few early Mesozoic examples from all of North America. Furthermore, this bract-scale complex is proposed as the earliest known occurrence of Araucaria section Eutacta based on its wedge-like shape, the centrally placed ovule that was retained at maturity, and lateral wings. An analysis of the relationship between the most current phylogenetic hypotheses for the sections of Araucaria and the temporal information from the rich fossil record of the genus indicates low levels of congruence. Clearly, more paleobotantical and phylogenetic research is needed to provide a robust estimate of this important conifer family's evolutionary history.
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Palaeontologia Electronica
http://palaeo-electronica.org
PE Article Number: 11.3.13A
Copyright: Palaeontological Association October 2008
Submission: 29 December 2007. Acceptance: 29 April 2008
Axsmith, Brian J., Escapa, Ignacio H., and Huber, Phillip. 2008. An Araucarian Conifer Bract-scale Complex from the Lower Jurassic
of Massachusetts: Implications for Estimating Phylogenetic and Stratigraphic Congruence in the Araucariaceae. Palaeontologia
Electronica Vol. 11, Issue 3; 13A:9p; http://palaeo-electronica.org/2008_3/153/index.html
AN ARAUCARIAN CONIFER BRACT-SCALE COMPLEX FROM THE
LOWER JURASSIC OF MASSACHUSETTS: IMPLICATIONS FOR
ESTIMATING PHYLOGENETIC AND STRATIGRAPHIC CONGRUENCE
IN THE ARAUCARIACEAE
Brian J. Axsmith, Ignacio H. Escapa, and Phillip Huber
ABSTRACT
The conifer family Araucariaceae has an extensive Mesozoic fossil record, but no
unambiguous megafossils of this group have been described from the Newark Super-
group of eastern North America. A bract-scale complex attributable to Araucaria is
described from the Lower Jurassic Portland Formation of Massachusetts. Although
known from a single specimen, this discovery is significant as the first bona fide
megafossil of the Araucariaceae from the Newark Supergroup and one of the few early
Mesozoic examples from all of North America. Furthermore, this bract-scale complex is
proposed as the earliest known occurrence of Araucaria section Eutacta based on its
wedge-like shape, the centrally placed ovule that was retained at maturity, and lateral
wings. An analysis of the relationship between the most current phylogenetic hypothe-
ses for the sections of Araucaria and the temporal information from the rich fossil
record of the genus indicates low levels of congruence. Clearly, more paleobotantical
and phylogenetic research is needed to provide a robust estimate of this important
conifer family’s evolutionary history.
Brian J. Axsmith. Department of Biology, University of South Alabama, LSCB 124, Mobile, AL 36688, USA,
baxsmith@jaguar1.usouthal.edu
Ignacio H. Escapa. CONICET, Museo Paleontologico Egidio Feruglio, Fontana 140, Trelew, Chubut,
Argentina, iescapa@mef.org.ar
Phillip Huber. GeoScience Books, P.O. Box 1036, Faribault, MN 55021 raregeologybooks@earthlink.net
KEY WORDS: Eutacta; phylogenetics; Mesozoic; Newark Supergroup; Portland Formation
INTRODUCTION
The conifer family Araucariaceae occurs
exclusively in the Southern Hemisphere today, but
it was widely distributed in both hemispheres dur-
ing the Mesozoic (Stockey 1982, 1994; Stockey
and Ko 1986; Hill 1995; Del Fueyo and Archangel-
sky 2002; Kunzman 2007a, 2007b). The mid-
Jurassic through Cretaceous record is particularly
rich in many regions, but early Mesozoic occur-
rences are uncommon and often ambiguous, espe-
cially in North America. Rare araucarian ovulate
cones and cone scales have recently been
described from the Late Triassic Chinle Formation
of Arizona and New Mexico (Axsmith and Ash
AXSMITH ET AL.: JURASSIC ARAUCARIAN
2
2006) and the Lower Jurassic Moenave Formation
of Utah (Tidwell and Ash 2006). Putative araucar-
ian megafossils have also been reported from the
Newark Supergroup of eastern North American
(e.g., Wanner and Fontaine 1900; Bock 1954), but
these are not generally accepted as convincing
evidence for the family (Cornet 1986; Stockey
1994; Axsmith and Ash 2006). It is in this context
that an unambiguous araucarian bract-scale com-
plex from the Lower Jurassic Holyoke Dam locality
of Massachusetts is described. Although known
from a single specimen, this discovery is significant
as the first certain megafossil of the Araucariaceae
from the Newark Supergroup and one of the few
early Mesozoic examples from all of North Amer-
ica. Furthermore, this bract-scale is similar to those
of Araucaria section Eutacta and may represent
the earliest known representative of this clade.
The extant species of Araucaria are com-
monly placed taxonomically among four sections;
Eutacta, Intermedia, Araucaria (= Columbea) and
Bunya (Endlicher 1847; Wilde and Eames 1952).
Several characters, including aspects of the bract-
scale morphology, are often used to distinguish
among the sections. These classic delimitations
are generally concordant with more recent molecu-
lar phylogenies (Gilmore and Hill 1997; Setoguchi
et al. 1998; Kunzmann 2007b); however, relation-
ships within the genus (i.e., between the sections)
remain unclear. Fossil species of Araucaria (as
well as Araucarites – see below) are represented
by impression/compression remains of vegetative
and reproductive organs from the Jurassic of the
Northern and Southern Hemispheres, and most of
these have been assigned to one of the sections of
Araucaria (see Stockey 1982; Del Fueyo and Arch-
angelsky 2002). These early records, along with
the fossil described here, allow for estimates of
phylogenetic/stratigraphic congruence, such as
that presented below.
MATERIALS AND METHODS
Nomenclatural Considerations
Historically, vegetative shoots ascribed to the
Araucariaceae have sometimes been described
using the generic name Araucarites; however, Zijl-
stra and Konijnenburg-van Cittert (2000) proposed
that this name be restricted to megasporangiate
cones and isolated bract-scale complexes. This
practice is acceptable when applied to early repre-
sentatives of the Araucariaceae with uncertain sec-
tional affinities or to more poorly preserved
material. However, the name Araucarites should
not be applied to material assigned to a particular
section, as such a determination must indicate
affinity with the genus Araucaria.
The generic name Araucaria is used here with
reference to the new Holyoke specimen, but it is
not formally named as a new species as it is repre-
sented by a single, isolated specimen that cannot
be definitively diagnosed from several Araucaria
section Eutacta bract-scale complexes. Some
other comparative taxa are referred to here as
Araucarites based on the original descriptions until
a thorough revision of the fossil record of the family
is available.
Locality and Geological Setting
The new Araucaria bract-scale complex was
collected from the South Hadley Falls Member of
the Portland Formation (Olsen et al. 2003, 2005),
from strata that crop out just below the dam in the
middle of the Connecticut River at Holyoke, Mas-
sachusetts (Figure 1). The Portland Formation con-
tains the youngest rocks of the Hartford Group,
Newark Supergroup and has been dated by
palynostratigraphy (Cornet and Waanders 2006)
and vertebrate biochronology (Lucas and Huber
2002) to span the Hettangian, Sinemurian, and
possibly Pliensbachian stages of the Early Juras-
sic. The South Hadley Falls Member is of Hettan-
gian age, and consists of gray and red lacustrine
shale and siltstone beds arranged in ~20 m thick
cycles, each of which has been interpreted as the
depositional product of the 20 Ky precessional
cycle (Olsen 1986; Olsen et al. 2003, 2005). At
Holyoke Dam and nearby exposures, the South
Hadley Falls Member contains an abundant,
allochthonous, low-diversity flora strongly domi-
nated by conifer branches with common equi-
setalian stem fragments and some cycadeoid
leaves. Other fossils from the South Hadley Falls
Member include fossil insect larvae (Huber et al.
2003), fragmentary fishes, and occasional thero-
pod dinosaur and crocodilian footprints (Olsen et
al. 2003, 2005). Although this locality has been
known for some time (see discussion in McDonald
1992) no detailed systematic work on the plant
material has been published despite the use of the
conifer shoots in paleoecological studies (e.g., Cor-
net and Waanders 2006). Based on the abundance
of Pagiophyllum and Brachyphyllum morphotype
leafy shoots, ovulate cone scales putatively similar
to Hirmeriella, and the dominance of dispersed
Classopollis pollen (Cornet et al 1973) at this and
coeval localities in the Hartford and Deerfield
Basins, most of this material has been assumed to
PALAEO-ELECTRONICA.ORG
3
Massachusetts
HD
HD :
Massachusetts
Vermont
Connecticut
Conglomerate
Fluvial Strata
Basalt
Lacustrine strata
Basament inlier
Holyoke Dam
15 km
400 km
References
N
Figure 1. Map of Newark Supergroup basins (left) and inset detail of Hartford Basin (right). Location of Holyoke Dam locality
(HD) indicated by arrow. Figure modified from Olsen, Whiteside, and Huber (2003).
AXSMITH ET AL.: JURASSIC ARAUCARIAN
4
represent the important Mesozoic conifer family
Cheirolepidiaceae. However, it has been previ-
ously suggested that some of the shoots may be
araucarian (Cornet and Waanders 2006). In fact,
the cuticular preservation of the leafy shoots is
poor (contra Cornet and Waanders 2006) and the
familial affinities of any of the specific leafy shoots
remain uncertain. An ongoing restudy of ovulate
cone scales and pollen cones from Holyoke Dam
does suggest dominance of the Cheirolepidiaceae;
however, the bract-scale complex described here
provides unequivocal macrofossil evidence of the
Araucariaceae in this flora.
Fossil Preparation and Study Methods
No special preparation of the fossil was per-
formed; however, it was immersed in ethanol to
increase contrast for photography (Figure 2.1). The
specimen exhibits considerable relief, which
makes it possible to delimit several important char-
acters under incident light, such as the position of
the ovule and the presence and orientation of the
wings. A thin layer of carbonaceous material is
present, but the application of the transfer tech-
nique was not attempted because it is the only
specimen, and attempts at transferring other fossils
from this locality were unsuccessful. The fossil
bract-scale complex specimen (# J 1430) will be
deposited in the collections of the Paleobotany
Division of the Natural History Museum and Biodi-
versity Research Center at the University of Kan-
sas. Comparative material of extant Araurcaria
species was examined and photographed in the
L.H. Bailey Hortorium of Cornell University.
Phylogenetic and Statistical Methods
Although the value of fossils in phylogenetic
reconstruction is controversial, the time of first
appearance of groups in the geological record is
widely used in calibrating phylogenies based on
molecular evidence. Furthermore, fossils are
sometimes used to describe the level of agreement
between the temporal sequence of taxa in the fos-
sil record and the order of branching on phylogenic
trees. Such congruence studies normally employ
one of two approaches; 1) methods that evaluate
the number of inconsistencies between the phylog-
eny and temporal data (Norell and Novaceck 1992;
Huelsenbeck 1994), and 2) methods that measure
calibrated “ghost lineages” or phylogenetically
implied gaps (Sidall 1998; Wills 1999; Pol and
Norell 2001) by which the absolute temporal dis-
parity is evaluated (Brochu and Norell 2000). In this
paper, the second approach is used to evaluate the
congruence between the current phylogenetic
hypotheses for the sections of Araucaria and the
temporal information from the fossil record of the
genus. Specifically, we used the analysis of Set-
Figure 2. Fossil and extant Araucaria bract-scale complexes. (1) Fossil Araucaria bract-scale complex from the Lower
Portland Formation of Massachusetts. Note the central seed-bearing region and lateral wings. # J 1430. (2) Bract-
scale complex of extant Araucaria heterophylla. (From specimen # BH 2732.) Note similarity to fossil in Figure 1.1.
Scale bars = 1.0 cm.
PALAEO-ELECTRONICA.ORG
5
oguchi et al. (1998), which produced one hypothe-
sis of relationships between the sections of
Araucaria and that of Gilmore and Hill (1997),
which produced two topologies–one perfectly con-
gruent with that of Setoguchi et al. (1998) in terms
of the sectional relationships and one different. The
Gilmore and Hill (1997) study used fewer Araucaria
species, but it included at least one species of
each monophyletic section of the genus (sensu
Setoguchi et al. 1998).
The first appearance datum (FAD) used for
each taxon is based on the literature for sections
Araucaria, Bunya, and Intermedia (e.g., Stockey
1994; Setoguchi et al. 1998). The FAD for section
Eutacta is based on the Holyoke bract-scale com-
plex described here. The Manhattan Stratigraphic
Measure (MSM) method originally proposed by
Sidall (1998) and later modified by Pol and Norell
(2001) designated as MSM* was utilized. In addi-
tion, the age uncertainty was considered with the
randomization approach for age ranges (Pol and
Norell 2006) using the MSM* to calculate the strati-
graphic fit for each of 1000 random replicates. This
analysis was performed using the phylogenetic
analysis software program TNT (Goloboff et al. in
press).
DESCRIPTION AND COMPARISONS
The Holyoke Araucaria bract-scale complex is
about 1.67 cm long, with only the most distal por-
tion missing (Figure 2.1). It is 0.8 cm wide at the
base and expands distally to 1.37 cm wide near the
apex. A single obovate seed, which is represented
by a distinct thickening in the middle of the com-
plex surface, is enclosed by the complex tissues.
On each side of the central seed-bearing zone is a
0.2 cm wide wing with longitudinal striations. The
seed-bearing zone is well defined due to the pres-
ence of two deep, longitudinal grooves that delin-
eate it from the wings. The distal part of the
complex shows a distinct thickening that is con-
cave toward the base. No ligule (free portion of the
ovuliferous scale) is visible, but this is probably due
to preservational factors. The basal part of the
complex shows three lobes; the central lobe is pro-
duced by the base of the seed-bearing region, and
the smaller lateral lobes are formed from the bases
of the wings.
The new Araucaria bract-scale complex is
most similar in shape, wing morphology, and ovule
disposition to those of section Eutacta of Araucaria.
Among extant species, it is particularly similar to
those of Araucaria heterophylla (Figure 2.2). In
comparison, bract-scale complexes of section
Araucaria (= Columbea) have a nut-like shape and
entirely lack wings, and those of section Bunya
have thicker woody wings, and the seed is shed
from the complex. Finally, the bract-scale wings of
section Intermedia are broader and thinner than
those of Eutacta.
Araucaria section Eutacta has a rich fossil his-
tory, and during the Mesozoic it was present in
both hemispheres (Stockey 1982; Hill and Brodribb
1999); however, most records are based on vege-
tative remains (Hill and Brodribb 1999). One
exception is Araucarites stockeyi from the Lower
Jurassic of Utah, which is suggested as a repre-
sentative of section Eutacta by Tidwell and Ash
(2006) based on the wedge-shaped bract-scale
complex with a short apical point, and the centrally
placed ovule that was apparently retained at matu-
rity. Although this may indeed be the earliest record
of section Eutacta, the wings of the Holyoke bract-
scale complex described here make it an even
more convincing representative. Araucarites phil-
lipsii from the Jurassic of Yorkshire (Kendall 1949;
Harris 1979; Van Konijnenburg-van Cittert and
Morgans 1999) has been referred to section
Eutacta based on characters of the ovuliferous
cones and seedlings (Stockey 1982). Bract-scale
complexes of Araucarites phillipsii are similar in
shape and size to the Holyoke Araucaria; however,
they do not show the clear delimitation of the seed-
bearing zone, and no distal thickening has been
observed. Araucarites baqueroensis and Araucar-
ites minimus from the Cretaceous of Argentina
have also been included in section Eutacta (Del
Fueyo and Archangelsky 2002). The bract-scale
complexes of these species are similar in general
morphology to the Holyoke specimen, but Araucar-
ites minimus is much smaller (nearly half of the
size) while Araucarite baqueroensis is consider-
ably larger. Another well-known species is Araucar-
ites brodiei, from middle Jurassic of Oxfordshire
(Cleal and Rees 2003). However, these fossils are
notably larger than the Holyoke Araucaria bract-
scale complex, the seed occupies the lower part of
the complex rather than the middle, and no wings
are present. In addition, the seed in Araucarites
brodiei is born in a depression on the bract-scale
but is not embedded in its tissues (Cleal and Rees
2003). In fact, this character suggests that this spe-
cies may not be close to Araucaria at all, as the
seeds of this genus are embedded in the tissues of
the bract-scale complex at least during some onto-
genetic stage. Based on these comparisons, it is
proposed that the Holyoke Araucaria bract-scale
complex provides enough features to be confi-
AXSMITH ET AL.: JURASSIC ARAUCARIAN
6
Figure 3. Stratigraphic fit of phylogenetic hypotheses for Araucaria sections. FADs are considered with uncertainty
intervals (entire lines); the dashed lines represent ghost lineages. (1) Stratigraphic adjustment for the classical
hypothesis (based on Gilmore and Hill 1997, Figures 3a, 4a, 4c and 4d; Setoguchi et al. 1998, Figure 1). (2) Strati-
graphic adjustment for alternative hypothesis (from Gilmore and Hill 1997, Figures 3b, 4b). (3) Frequency histogram
of the difference in MSM*values of both hypotheses obtained in each replicate of the randomization procedure. The
MSM* difference between the classical and alternative hypothesis is positive (or zero) in all replicates indicating that
the alternative hypothesis score is equal to or lower than the classical one in stratigraphic fit (represented by
MSM*value).
PALAEO-ELECTRONICA.ORG
7
dently assigned to Araucaria section Eutacta and
represents the earliest record of this section.
DISCUSSION
Phylogenetic/stratigraphic Congruence
Measures of phylogenetic/stratigraphic con-
gruence for the Araucariaceae utilizing the statisti-
cal tests, fossil taxa, and phylogenies described
above were surprisingly low.
The range of MSM* values obtained for the
sectional relationships within Araucaria is 0.51-
0.84 for the classical phylogenetic hypothesis
(Gilmore and Hill 1997, Figures 3a, 4a, 4c and 4d;
Setoguchi et al. 1998, Figure 1) (Figures 3.1 and
3.3), and 0.5-0.67 for the alternative one (Gilmore
and Hill 1997, Figures 3b, 4b) (Figures 3.2 and
3.3). These relatively low values are probably
related to the incongruence between the FAD
ranges of the sections and their position on both
tree topologies (Figure 3.1-3.2), generating a long
temporal ghost for some lineages. Alternatively, the
broad MSM* range obtained with the FAD dates
used in this study may reflect the high degree of
uncertainty in determining the precise ages of most
of the sections. For example, the Lower Creta-
ceous FAD range for Section Intermedia covers
about 43 million years. Another potential problem
is the lack of fossil taxa as terminals in the phyloge-
netic analyses utilized.
Conclusion
Ideally, a clade with a rich fossil record and a
well-resolved phylogenetic hypothesis should show
high levels of congruence among these data sets.
The Araucariaceae would seem to satisfy the
requirements for high phylogenetic/stratigraphic
congruence, as the family is considered to have a
particularly long and rich fossil record, and sub-
stantial living diversity to provide abundant data for
phylogenetic studies. Nevertheless, the analysis
presented here indicates that much more research
is needed, probably in both areas, to provide a
more consistent estimate of this important conifer
family’s evolutionary history. This will most likely
entail the continued discovery and description of
new fossils as well as a critical re-evaluation of
known fossil taxa. In addition, it is likely that phylo-
genetic studies based only on extant taxa underes-
timate the true complexity of araucarian phylogeny,
as the fossil record indicates high levels of extinct
diversity, including completely extinct sections
(e.g., Yezonia) with unique character combinations
(Ohsawa et al. 1995). The inclusion of well-pre-
served and reconstructed fossil taxa in a combined
analysis of the Araucariaceae should provide new
data regarding those parts of the phylogeny cur-
rently represented by ghost lineages leading to a
more robust phylogenetic hypothesis and improved
phylogenetic/stratigraphic congruence.
Regardless of the causes of the current phylo-
genetic/stratigraphic incongruence for the Araucar-
iaceae, the bract/scale complex described here is
significant as the first bona fide megafossil of the
Araucariaceae from the Newark Supergroup and
one of the few early Mesozoic examples from all of
North America. This fossil is also significant as the
earliest record of Araucaria section Eutacta.
Although plant fossils have been known from the
Newark Supergroup for many years, there is little
question that it remains an underutilized source of
information regarding early Mesozoic plant evolu-
tion.
ACKNOWLEDGEMENTS
The authors are grateful to the staff of the L.H.
Bailey Hortorium at Cornell University for access to
herbarium specimens. This research was sup-
ported by a National Science Foundation Grant
(EAR-0105476) to B.J.A.TNT is freely available,
thanks to a subsidy from the Willi Hennig Society.
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... Araucaria has a famously rich fossil history worldwide, in contrast to its modern, fragmented Southern Hemisphere range, and the genus was highly diverse during the Mesozoic (Stockey, 1982(Stockey, , 1994Hill and Brodribb, 1999;Kershaw and Wagstaff, 2001;Kunzmann, 2007;Panti et al., 2012). Mesozoic fossils with varying degrees of completeness have been suggested to represent Araucaria section Eutacta (i.e., Seward, 1903;Kendall, 1949;Archangelsky, 1966;Bose and Maheshwari, 1973;Harris, 1979;Cantrill, 1992;Pole, 1995;Cantrill and Falcon-Lang, 2001;Axsmith et al., 2008;van der Ham et al., 2010), but there is no consensus on their relationships (Stockey, 1994;Leslie et al., 2012). The majority of Cenozoic macrofossil records of Araucaria Sect. ...
... Eutacta range from ~57 to ~145 Ma (Leslie et al., 2012, depending on the calibrations and methods used, contrasting with some fossil evidence suggesting a minimum age of ca. 190 Ma (Axsmith et al., 2008). Molecular crown ages of Sect. ...
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Premise: Eocene floras of Patagonia document biotic response to the final separation of Gondwana. The conifer genus Araucaria, distributed worldwide during the Mesozoic, has a disjunct extant distribution between South America and Australasia. Fossils assigned to Australasian Araucaria Sect. Eutacta usually are represented by isolated organs, making diagnosis difficult. Araucaria pichileufensis E.W. Berry, from the middle Eocene Río Pichileufú (RP) site in Argentine Patagonia, was originally placed in Sect. Eutacta and later reported from the early Eocene Laguna del Hunco (LH) locality. However, the relationship of A. pichileufensis to Sect. Eutacta and the conspecificity of the Araucaria material among these Patagonian floras have not been tested using modern methods. Methods: We review the type material of A. pichileufensis alongside large (n = 192) new fossil collections of Araucaria from LH and RP, including multi-organ preservation of leafy branches, ovuliferous complexes, and pollen cones. We use a total evidence phylogenetic analysis to analyze relationships of the fossils to Sect. Eutacta. Results: We describe Araucaria huncoensis sp. nov. from LH and improve the whole-plant concept for Araucaria pichileufensis from RP. The two species respectively resolve in the crown and stem of Sect. Eutacta. Conclusions: Our results confirm the presence and indicate the survival of Sect. Eutacta in South America during early Antarctic separation. The exceptionally complete fossils significantly predate several molecular age estimates for crown Eutacta. The differentiation of two Araucaria species demonstrates conifer turnover during climate change and initial South American isolation from the early to middle Eocene.
... 190 Ma) of eastern North America, which has been proposed as the earliest known occurrence of Araucaria section Eutacta (Link) Endl. [31]. It should be noted that this fossil age is not inconsistent with several other well documented fossil types (e.g. ...
... If the Araucaria crown group radiated not more than c. 100 Ma (Figure 1; Table 2) this casts doubt on the status of several relatively ancient fossil types with putative affinities to extant taxa (e.g. Axsmith et al., 2008). However, aspects of this record have previously been questioned on a number of grounds. ...
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New Caledonia is a global biodiversity hotspot. Hypotheses for its biotic richness suggest either that the island is a 'museum' for an old Gondwana biota or alternatively it has developed following relatively recent long distance dispersal and in situ radiation. The conifer genus Araucaria (Araucariaceae) comprises 19 species globally with 13 endemic to this island. With a typically Gondwanan distribution, Araucaria is particularly well suited to testing alternative biogeographic hypotheses concerning the origins of New Caledonian biota. We derived phylogenetic estimates using 11 plastid and rDNA ITS2 sequence data for a complete sampling of Araucaria (including multiple accessions of each of the 13 New Caledonian Araucaria species). In addition, we developed a dataset comprising 4 plastid regions for a wider taxon sample to facilitate fossil based molecular dating. Following statistical analyses to identify a credible and internally consistent set of fossil constraints, divergence times estimated using a Bayesian relaxed clock approach were contrasted with geological scenarios to explore the biogeographic history of Araucaria. The phylogenetic data resolve relationships within Araucariaceae and among the main lineages in Araucaria, but provide limited resolution within the monophyletic New Caledonian species group. Divergence time estimates suggest a Late Cretaceous-Cenozoic radiation of extant Araucaria and a Neogene radiation of the New Caledonian lineage. A molecular timescale for the evolution of Araucariaceae supports a relatively recent radiation, and suggests that earlier (pre-Cenozoic) fossil types assigned to Araucaria may have affinities elsewhere in Araucariaceae. While additional data will be required to adequately resolve relationships among the New Caledonian species, their recent origin is consistent with overwater dispersal following Eocene emersion of New Caledonia but is too old to support a single dispersal from Australia to Norfolk Island for the radiation of the Pacific Araucaria sect. Eutacta clade.
... During the Mesozoic, the conifer family Araucariaceae was distributed throughout the Northern and Southern Hemispheres (Stockey, 1982(Stockey, , 1994Stockey and Ko, 1986;Hill, 1995;Del Fueyo and Archangelsky, 2002;Axsmith et al., 2008). Its fossil record is remarkably rich from the Lower Jurassic to the Upper Cretaceous, although Triassic occurrences are less common and often have doubtful affinities with the family (Stockey, 1982;Dettmann et al., 2012;Rothwell et al., 2012). ...
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In this contribution, fossil woods from the Valle de La Luna Member of the Upper Triassic Ischigualasto Formation at Ischigualasto Provincial Park, San Juan Province, Argentina, are described. The specimens are preserved as silica permineralization in tuffs intercalated with carbonaceous mudstone beds interpreted as distal floodplain facies. The fossil woods were assigned to the new species Agathoxylon argentinum since their anatomy differs from the known Mesozoic Gondwanan species of the genus Agathoxylon. The combination of characters present in the new taxon indicates an affiliation with the conifer family Araucariaceae. Signals of fungal-mediated wood decay were observed, comparable to the activity of basidiomycetes. Spherical structures attached to the walls of the tracheids were recognized and are interpreted as holocarpic chytrid fungi. The growth rings were quantitatively analyzed. Low values of percentage diminution, percentage latewood, and Ring Markedness Index, and a mean percentage skew of +11.5, were obtained, suggesting that the new species was an evergreen gymnosperm. The stratigraphic distribution and taxonomic composition of the Ischigualasto Formation fossil-plant-bearing levels were studied. A vegetation change is recorded in the fossil level bearing Agathoxylon argentinum n. sp., marked by the replacement of the corystosperm genera and a diminution of arboreal corystosperms. This floristic change, in addition to other evidence, indicates humid paleoclimatic conditions for the uppermost part of the Valle de La Luna Member of the Ischigualasto Formation.
... The Cretaceous amber included in the study is primarily produced by either Araucariaceae or Cheirolepidiaceaey, although some could be of Cupressaceae-Taxodiaceae origin or even of unknown origin. Today, araucariaceans comprise 41 species in three genera (Araucaria, Agathis, Wollemia) that are restricted to the Southern Hemisphere, and found throughout parts of South America, Malaysia, Australia, New Zealand, and New Caledonia (Kunzmann, 2007;Stockey and Rothwell, 2020); that distribution is a relic of their Gondwana origin (Del Fueyo and Archangelsky, 2002;Axsmith et al., 2008). Their more widespread distribution during the Cretaceous is evidenced by numerous araucariacean fossils and amber deposits in Europe, Levant region, the United States, and North Asia (Stockey and Rothwell, 2003;Kunzmann, 2007). ...
Article
Chemical analysis of amber, copal, and resin is a valuable tool for interpreting the botanic origin of amber and the ecological role of resin in ancient forests. Here we investigated for the first time the volatile and semi-volatile composition of Cretaceous amber, as well as copal and Defaunation resin produced by trees of the family Araucariaceae (Gymnospermae: Pinidae), via solid-phase microextraction gas chromatography-mass spectrometry. Principal component analysis (PCA) revealed a clear distinction between the Pleistocene copal/Defaunation resin and the much older Cretaceous amber samples. However, even among the younger resin samples whose plant producers were identified to the species level, the PCA did not clearly distinguish the groups, either at the species level or at the genus level. Therefore, even with ideal preservation of original chemistry, PCA of SPME GC/MS data will not differentiate varying botanic origins in the Cretaceous amber samples. There was extensive variation observed in the composition of the amber samples, but no separate groups in the PCA. This amber chemistry was most likely influenced by multiple factors, such as variable original resin chemistry and variable maturation as the most relevant. The Cretaceous amber deposits are proposed to represent forests with multiple taxa (even multiple families) of resin-producing trees, which varied over space and time, rather than representing a widespread and homogenous forest. As resin composition is strongly affected by both taxonomy of the resin-producing tree and ecological factors such as herbivory and pathogens, we propose that these forests were exposed to varying combinations of ecological factors.
... Araucariaceae: Extensive fossil record, poor congruence-The fossil record of Araucariaceae is extensive and well documented (see Stockey, 1982Stockey, , 1994Kunzmann, 2007), but of all the major conifer clades, theirs is the most difficult to reconcile with molecular topologies and estimated divergence ages. Putative Araucariaceae first appear in the Late Triassic (Axsmith and Ash, 2006), with the earliest unambiguous members present by the Lower Jurassic (Arrondo and Petriella, 1980;Axsmith et al., 2008). By the Middle Jurassic, seed cones consistent with placement in the extant genus Araucaria are present in both the Northern and Southern Hemispheres (Stockey, 1975(Stockey, , 1980. ...
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Premise of the Study Conifers are an important living seed plant lineage with an extensive fossil record spanning more than 300 million years. The group therefore provides an excellent opportunity to explore congruence and conflict between dated molecular phylogenies and the fossil record. Methods We surveyed the current state of knowledge in conifer phylogenetics to present a new time‐calibrated molecular tree that samples ~90% of extant species diversity. We compared phylogenetic relationships and estimated divergence ages in this new phylogeny with the paleobotanical record, focusing on clades that are species‐rich and well known from fossils. Key Results Molecular topologies and estimated divergence ages largely agree with the fossil record in Cupressaceae, conflict with it in Araucariaceae, and are ambiguous in Pinaceae and Podocarpaceae. Molecular phylogenies provide insights into some fundamental questions in conifer evolution, such as the origin of their seed cones, but using them to reconstruct the evolutionary history of specific traits can be challenging. Conclusions Molecular phylogenies are useful for answering deep questions in conifer evolution if they depend on understanding relationships among extant lineages. Because of extinction, however, molecular datasets poorly sample diversity from periods much earlier than the Late Cretaceous. This fundamentally limits their utility for understanding deep patterns of character evolution and resolving the overall pattern of conifer phylogeny.
... Traditionally, the ancestral configuration of the seed cones of Araucaria was interpreted as showing heavy, woody-winged cone scale complexes (Wilde and Eames, 1948) because Jurassic members assigned to the genus show cone scale complexes with welldeveloped, woody wings (Kendall, 1949;Calder, 1953;Stockey, 1975Stockey, , 1980Axsmith et al., 2008). However, it is yet to be determined whether these species belong to the crown or stem group of the genus or even to the stem group of the family (Kunzmann, 2007). ...
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PREMISE OF THE STUDY: We describe a new araucarian species, Araucaria lefipanensis, from the Late Cretaceous flora of the Lefipán Formation, in Patagonia (Argentina) based on reproductive and vegetative remains, with a combination of characters that suggest mosaic evolution in the Araucaria lineage. METHODS: The studied fossils were found at the Cañadón del Loro locality. Specimens were separated into two leaf morphotypes, and their morphological differences were tested with MANOVA. KEY RESULTS: The new species Araucaria lefipanensis is erected based on the association of dimorphic leaves with cuticle remains and isolated cone scale complexes. The reproductive morphology is characteristic of the extant section Eutacta, whereas the vegetative organs resemble those of the sections Intermedia, Bunya, and Araucaria (the broad-leaved clade). CONCLUSIONS: The leaf dimorphism of A. lefipanensis is similar to that of extant A. bidwillii, where dimorphism is considered to be related to seasonal growth. The leaf dimorphism in A. lefipanensis is consistent with the paleoclimatic and paleoenvironmental reconstructions previously suggested for the Lefipán Formation, which is thought to have been a seasonal subtropical forest. The new species shows evidence of mosaic evolution, with cone scale complexes morphologically similar to section Eutacta and leaves similar to the sections of the broad-leaved clade, constituting a possible transitional form between these two well-defined lineages. More complete plant concepts, especially those including both reproductive and vegetative remains are necessary to understand the evolution of ancient plant lineages. This work contributes to this aim by documenting a new species that may add to the understanding of the early evolution of the sections of Araucaria.
... We therefore attribute the Antarctic Eocene bract-scale complex to Araucaria, even though the fossil does not show free tip of the ovuliferous scale (the so called 'ligule') that is diagnostic for extant members of the genus (Farjon 2010). The lack of this structure is not surprising (also see Axsmith et al. 2008;van der Ham et al. 2010), however, as it is not especially large and could be obscured by the bract itself in impression or compression fossils. Additionally, this structure is only present on one of the two surfaces of the complex (the adaxial surface), so a given fossil specimen essentially has a 50% chance of showing it. ...
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The early-middle Eocene Fossil Hill flora from King George Island in the Antarctic Peninsula regions is one of the most diverse Cenozoic plant assemblages in Antarctica. It represents a rich Nothofagus and conifer dominated vegetation. These plant fossils, especially conifers are of crucial importance for understanding the biogeographic history of the Gondwanan plants. Here we describe the first Araucaria bract-scale complex, A. fildesensis sp. nov., and associated foliage from the Fossil Hill flora and tentatively assigned them to the Section Eutacta, which is today restricted to Australasia, based on comparison with extant material. This study confirms that Araucaria species with small bract-scale complexes, small scale-like mature leaves and awl-shaped juvenile leaves like those of extant Section Eutacta, lived in Antarctica in the Eocene. These fossils provide potential evidence for the trans-Antarctic floristic changes of Araucaria species in the Section Eutacta between southern Australia and southern South America during the Eocene, when Antarctica was ice-free and forested.
... Divergence time estimates from the study by Kranitz et al. [16] indicated that the stem origin of Araucaria was in the Early Cretaceous to Paleocene (~138-60 mya) and that of the Araucariaceae in the Permian-Triassic (~284-202 mya). However, fossils of Araucaria were dated as far back as the Lower Jurassic (~200 to 176 mya) [17]. It is unclear (i) whether the parasitic association between Uleiella and Araucaria is the result of co-evolution or a host jump; (ii) whether Uleiella predates its host plant; and (iii) whether Uleiella is ancestral to the smut fungi. ...
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The evolutionary history, divergence times and phylogenetic relationships of Uleiella chilensis (Ustilaginomycotina, smut fungi) associated with Araucaria araucana were analysed. DNA sequences from multiple gene regions and morphology were analysed and compared to other members of the Basidiomycota to determine the phylogenetic placement of smut fungi on gymnosperms. Divergence time estimates indicate that the majority of smut fungal orders diversified during the Triassic-Jurassic period. However, the origin and relationships of several orders remain uncertain. The most recent common ancestor between Uleiella chilensis and Violaceomyces palustris has been dated to the Lower Cretaceous. Comparisons of divergence time estimates between smut fungi and host plants lead to the hypothesis that the early Ustilaginomycotina had a saprobic lifestyle. As there are only two extant species of Araucaria in South America, each hosting a unique Uleiella species, we suggest that either coevolution or a host shift followed by allopatric speciation are the most likely explanations for the current geographic restriction of Uleiella and its low diversity. Phylogenetic and age estimation analyses, ecology, the unusual life-cycle and the peculiar combination of septal and haustorial characteristics support Uleiella chilensis as a distinct lineage among the Ustilaginomycotina. Here, we describe a new ustilaginomycetous order, the Uleiellales to accommodate Uleiella. Within the Ustilaginomycetes, Uleiellales are sister taxon to the Violaceomycetales.
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Premise: Exceptional anatomical preservation of a fossil araucarian seed cone from a marine carbonate concretion from Vancouver Island, British Columbia, Canada provides unusually complete evidence for cone structure including seeds, megagametophytes, microgametophytes, and embryos of an Upper Cretaceous (Campanian) species of Araucaria, providing important new insights into the structure and relationships of Cretaceous Northern Hemisphere Araucariaceae. Methods: The cone was studied from serial thin sections prepared by the coal ball peel technique. Phylogenetic analysis using a modified morphological matrix with both discrete and continuous characters was performed using TNT version 1.5. Results: The nearly spherical cone, 6 × 6 cm in diameter, has helically arranged cone-scale complexes, consisting of a large bract with an upturned tip and a small, fleshy ovuliferous scale. Vascularization of the cone-scale complex is single at its origin. Widely winged bracts, with a bulging base, contain numerous vascular bundles, interspersed with transfusion tissue, and a large number of resin canals. Seeds are ovoid, 1.2 cm long, 1.2 cm in diameter. Nucellus is free from the integument, except at its base, with a convoluted apex, containing possible pollen tubes. Megagametophytes and mature cellular embryos occur in several seeds. Conclusions: This small cone with attached, imbricate leaves, wide bracts, and unusually large seeds, most closely resembles those of Araucaria Section Eutacta. Width and continuity of secondary xylem in the cone axis, and intact cone-scale complexes indicate that this cone probably did not disarticulate readily at maturity. When added to a modified, previously published phylogenetic analysis, Araucaria famii sp. nov. enhances our understanding of the Cretaceous radiation of Northern Hemisphere Araucaria Section Eutacta.
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Premise of the Study The fossil record of Agathis historically has been restricted to Australasia. Recently described fossils from the Eocene of Patagonian Argentina showed a broader distribution than found previously, which is reinforced here with a new early Paleocene Agathis species from Patagonia. No previous phylogenetic analyses have included fossil Agathis species. Methods We describe macrofossils from Patagonia of Agathis vegetative and reproductive organs from the early Danian, as well as leaves with Agathis affinities from the latest Maastrichtian. A total evidence phylogenetic analysis is performed, including the new Danian species together with other fossil species having agathioid affinities. Key Results Early Danian Agathis immortalis sp. nov. is the oldest definite occurrence of Agathis and one of the most complete Agathis species in the fossil record. Leafy twigs, leaves, pollen cones, pollen, ovuliferous complexes, and seeds show features that are extremely similar to the living genus. Dilwynites pollen grains, associated today with both Wollemia and Agathis and known since the Turonian, were found in situ within the pollen cones. Conclusions Agathis was present in Patagonia ca. 2 million years after the K‐Pg boundary, and the putative latest Cretaceous fossils suggest that the genus survived the K–Pg extinction. Agathis immortalis sp nov. is recovered in a stem position for the genus, while A. zamunerae (Eocene, Patagonia) is recovered as part of the crown. A Mesozoic divergence for the Araucariaceae crown group, previously challenged by molecular divergence estimates, is supported by the combined phylogenetic analyses including the fossil taxa.
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The three southern conifer families, Araucariaceae, Cupressaceae and Podocarpaceae, have a long history and continue to be an important part of the vegetation today. The Araucariaceae have the most extensive fossil record, occurring in both hemispheres, and with Araucaria in particular having an ancient origin. In the Southern Hemisphere Araucaria and Agathis have substantial macrofossil records, especially in Australasia, and Wollemia probably also has an important macrofossil record. At least one extinct genus of Araucariaceae is present as a macrofossil during the Cenozoic. Cupressaceae macrofossils are difficult to identify in older sediments, but the southern genera begin their record in the Cretaceous (Athrotaxis) and become more diverse and extensive during the Cenozoic. Several extinct genera of Cupressaceae also occur in Cretaceous and Cenozoic sediments in Australasia. The Podocarpaceae probably begin their macrofossil record in the Triassic, although the early history is still uncertain. Occasional Podocarpaceae macrofossils have been recorded in the Northern Hemisphere, but they are essentially a southern family. The Cenozoic macrofossil record of the Podocarpaceae is extensive, especially in south-eastern Australia, where the majority of the extant genera have been recorded. Some extinct genera have also been reported from across high southern latitudes, confirming an extremely diverse and widespread suite of Podocarpaceae during the Cenozoic in the region. In the Southern Hemisphere today conifers achieve greatest abundance in wet forests. Those which compete successfully with broad-leaved angiosperms in warmer forests produce broad, flat photosynthetic shoots. In the Araucariaceae this is achieved by the planation of multiveined leaves into large compound shoots. In the other two families leaves are now limited to a single vein (except Nageia), and to overcome this limitation many genera have resorted to re-orientation of leaves and two-dimensional flattening of shoots. The Podocarpaceae show greatest development of this strategy with 11 of 19 genera producing shoots analogous to compound leaves. The concentration of conifers in wet forest left them vulnerable to the climate change which occurred in the Cenozoic, and decreases in diversity have occurred since the Paleogene in all regions where fossil records are available. Information about the history of the dry forest conifers is extremely limited because of a lack of fossilisation in such environments. The southern conifers, past and present, demonstrate an ability to compete effectively with angiosperms in many habitats and should not be viewed as remnants which are ineffectual against angiosperm competitors.
Chapter
The diverse depositional environments and rich fossil assemblages of the early Mesozoic Newark Supergroup of eastern North America can be subdivided into six broad environmental categories ranging from fault-scarp breccias in synsedimentary grabens developed directly along master boundary fault zones to deep-water zones of lakes. Each environmental category is characterized by its own range of taxa and modes of preservation. Environmental zones, except those directly caused by faulting, shifted laterally as lake levels rose and fell. Overt analogy between the lower trophic levels of aquatic ecosystems of modern lakes and those of the early Mesozoic is not appropriate. Diatoms were absent from the phytoplankton and large (0.3–1.0 cm) clam-shrimp comprised most of the zooplankton in Newark lakes, despite the abundant planktivorous fish.
Article
This paper deals with the taxonomic and historical background of the genus Araucaria with a discussion and evaluation of characters used as a basis for sectional division. The three existing sections are more clearly delimited and a new section-Sectio Bunya-is proposed for A. Bidwilli, which is removed from section Columbea. A key to the four sections is given.